Tracheal intubation
Encyclopedia
Tracheal intubation, usually simply referred to as intubation
, is the placement of a flexible plastic or rubber tube
into the trachea
(windpipe) to maintain an open airway
or to serve as a conduit through which to administer certain drugs. It is frequently performed in critically injured, ill or anesthetized patients to facilitate ventilation
of the lungs, including mechanical ventilation
, and to prevent the possibility of asphyxia
tion or airway obstruction. The most widely used route is orotracheal, in which an endotracheal tube
is passed through the mouth and vocal apparatus
into the trachea. In a nasotracheal procedure, an endotracheal tube is passed through the nose and vocal apparatus into the trachea. Other methods of intubation involve surgery and include the cricothyrotomy
(used almost exclusively in emergency circumstances) and the tracheotomy
, used primarily in situations where a prolonged need for airway support is anticipated, surgical methods are also used in emergency situations when conventional endotracheal intubation is not possible.
Because it is an invasive
and extremely uncomfortable medical procedure
, intubation is usually performed after administration of general anesthesia
and a neuromuscular-blocking drug
. It can however be performed in the awake patient with local
or topical anesthesia
, or in an emergency without any anesthesia at all. Intubation is normally facilitated by using a conventional laryngoscope
, flexible fiberoptic bronchoscope
or video laryngoscope to identify the glottis
, though other devices and techniques are available. After the trachea has been intubated, a balloon cuff is typically inflated just above the far end of the tube to help secure it in place, to prevent leakage of respiratory gases, and to protect the tracheobronchial tree
from receiving undesirable material
such as stomach acid. The tube is then secured to the face or neck and connected to a T-piece, anesthesia breathing circuit, bag valve mask
device, or a mechanical ventilator
. Once there is no longer a need for ventilatory assistance and/or protection of the airway, the tracheal tube is removed; this is referred to as extubation of the trachea (or decannulation, in the case of a surgical airway such as a cricothyrotomy or a tracheotomy).
For centuries, tracheotomy was considered the only reliable method for intubation of the trachea. However, because only a minority of patients survived the operation, physicians undertook tracheotomy only as a last resort, on patients who were nearly dead. It was not until the late 19th century however that advances in anatomy
and physiology
, as well an appreciation of the germ theory of disease
, had improved the outcome of this operation to the point that it could be considered an acceptable treatment option. Also at that time, advances in endoscopic
instrumentation had improved to such a degree that direct laryngoscopy had become a viable means to secure the airway by the non-surgical orotracheal route. By the mid-20th century, the tracheotomy as well as endoscopy and non-surgical tracheal intubation had evolved from rarely employed procedures to becoming essential components of the practices of anesthesiology
, critical care medicine, emergency medicine
, gastroenterology
, laryngology
, pulmonology
and surgery
.
Tracheal intubation can be associated with minor complications
such as broken teeth or lacerations of the tissues
of the upper airway
. It can also be associated with potentially fatal complications such as pulmonary aspiration of stomach contents which can result in a severe and sometimes fatal chemical aspiration pneumonitis
, or unrecognized intubation of the esophagus
which can lead to potentially fatal anoxia
. Because of this, the potential for difficulty or complications due to the presence of unusual airway anatomy or other uncontrolled variables is carefully evaluated before undertaking tracheal intubation. Alternative strategies for securing the airway must always be readily available. The incidence of serious complications is unacceptably high when undertaken by practitioners lacking adequate training and experience.
in a variety of situations when illness or a medical procedure prevents a person from maintaining a clear airway, breathing, and oxygenating
the blood. In these circumstances, oxygen supplementation
using a simple face mask
is inadequate.
Depressed level of consciousness
Perhaps the most common indication for tracheal intubation is for the placement of a conduit through which nitrous oxide
or volatile anesthetics may be administered. General anesthetic agents
, opioid
s, and neuromuscular-blocking drugs may diminish
or even abolish
the respiratory drive
. Although it is not the only means to maintain a patent airway during general anesthesia, intubation of the trachea provides the most reliable means of oxygenation and ventilation
and the greatest degree of protection against regurgitation and pulmonary aspiration.
Damage to the brain (such as from a massive stroke
, non-penetrating head injury, intoxication or poison
ing) may result in a depressed level of consciousness
. When this becomes severe to the point of stupor
or coma
(defined as a score on the Glasgow Coma Scale
of less than 8), dynamic collapse of the extrinsic muscles of the airway can obstruct the airway, impeding the free flow of air into the lungs. Furthermore, protective airway reflexes such as cough
ing and swallowing
may be diminished or absent. Tracheal intubation is often required to restore patency (the relative absence of blockage) of the airway and protect the tracheobronchial tree from pulmonary aspiration of gastric contents.
Hypoxemia
Intubation may be necessary for a patient with decreased oxygen content
and oxygen saturation
of the blood caused when their breathing is inadequate (hypoventilation
), suspended (apnea
), or when the lungs are unable to sufficiently transfer gasses to the blood
. Such patients, who may be awake and alert, are typically critically ill with a multisystem disease or multiple severe injuries. Examples of such conditions include cervical spine injury
, multiple rib fractures
, severe pneumonia
, acute respiratory distress syndrome
(ARDS), or near-drowning
. Specifically, intubation is considered if the arterial
partial pressure
of oxygen (PaO2) is less than 60 millimeters of mercury
(mm Hg) while breathing an inspired O2 concentration (FIO2
) of 50% or greater. In patients with elevated arterial carbon dioxide
, an arterial partial pressure of CO2 (PaCO2) greater than 45 mm Hg in the setting of acidemia
would prompt intubation, especially if a series of measurements demonstrate a worsening respiratory acidosis
. Regardless of the laboratory values, these guidelines are always interpreted in the clinical context.
Airway obstruction
Actual or impending airway obstruction is a common indication for intubation of the trachea. Life-threatening airway obstruction may occur when a foreign body
becomes lodged in the airway; this is especially common in infants and toddlers. Severe blunt
or penetrating
injury to the face or neck may be accompanied by swelling
and an expanding hematoma
, or injury to the larynx, trachea or bronchi
. Airway obstruction is also common in people who have suffered smoke inhalation
or burns within close to the airway or epiglottitis
caused by infection. Sustained generalized seizure activity and angioedema
are other common causes of life-threatening airway obstruction which may require tracheal intubation to secure the airway.
Manipulation of the airway
Diagnostic or therapeutic manipulation of the airway (such as bronchoscopy, laser therapy
or stent
ing of the bronchi
) may intermittently interfere with the ability to breathe; intubation may be necessary in such situations.
s, which are either straight or curved. This device is designed to allow the laryngoscopist to directly view the larynx. Due to the widespread availability of such devices, the technique of blind digital intubation of the trachea is rarely practiced today, although it may still be useful in certain emergency situations, such as natural or man-made disasters.
The decision to use a straight or curved laryngoscope blade depends partly on the specific anatomical features of the airway, and partly on the personal experience and preference of the laryngoscopist. The Macintosh
blade is the most widely used curved laryngoscope blade, while the Miller blade is the most popular style of straight blade. Both Miller and Macintosh laryngoscope blades are available in sizes 0 (infant) through 4 (large adult). There are many other styles of straight and curved blades, with accessories such as mirrors for enlarging the field of view and even ports for the administration of oxygen
. These specialty blades are primarily designed for use by anesthetist
s and otolaryngologists
, most commonly in the operating room.
Fiberoptic
layngoscopes have become increasingly available since the 1990s. In contrast to the conventional laryngoscope, these devices allow the laryngoscopist to indirectly view the larynx. This provides a significant advantage in situations where the operator needs to see around an acute bend in order to visualize the glottis, and deal with otherwise difficult intubations. Video laryngoscopes are specialized fiberoptic layngoscopes that use a digital video camera sensor
to allow the operator to view the glottis and larynx on a video monitor. Other "noninvasive" devices which can be employed to assist in tracheal intubation are the laryngeal mask airway
(used as a conduit for endotracheal tube placement) and the AirTraq.
The Eschmann tracheal tube introducer (often incorrectly referred to as a "gum elastic bougie") is specialized type of stylet used to facilitate difficult intubation. This flexible device is 60 cm (23.6 in) in length, 15 French
(5 mm diameter) with a small "hockey-stick" angle at the far end. Unlike a traditional intubating stylet, the Eschmann tracheal tube introducer is typically inserted directly into the trachea and then used as a guide over which the endotracheal tube can be passed (in a manner analogous to the Seldinger technique
). As the Eschmann tracheal tube introducer is considerably less rigid than a conventional stylet, this technique is considered to be a relatively atraumatic means of tracheal intubation.
The tracheal tube exchanger is a hollow catheter
, 56 to 81 cm (22 to 31.9 in) in length, that can be used for removal and replacement of tracheal tubes without the need for laryngoscopy. The Cook Airway Exchange Catheter (CAEC) is another example of this type of catheter; this device has a central lumen
(hollow channel) through which oxygen can be administered
.
The lighted stylet is a device that employs the principle of transillumination
to facilitate blind orotracheal intubation (an intubation technique in which the laryngoscopist does not view the glottis).
A tracheal tube is a catheter that is inserted into the trachea for the primary purpose of establishing and maintaining a patent (open and unobstructed) airway. Tracheal tubes are frequently used for airway management
in the settings of general anesthesia, critical care, mechanical ventilation and emergency medicine. Many different types of tracheal tubes are available, suited for different specific applications. An endotracheal tube is a specific type of tracheal tube that is nearly always inserted through the mouth (orotracheal) or nose (nasotracheal). It is a breathing
conduit designed to be placed into the airway of critically injured, ill or anesthetized patients in order to perform mechanical positive pressure ventilation of the lungs and to prevent the possibility of aspiration or airway obstruction. The endotracheal tube has a fitting designed to be connected to a source of pressurized gas such as oxygen. At the other end is an orifice through which such gases are directed into the lungs and may also include a balloon (referred to as a cuff). The tip of the endotracheal tube is positioned above the carina
(before the trachea divides to each lung) and sealed within the trachea so that the lungs can be ventilated equally. A tracheostomy tube is another type of tracheal tube; this 2–3 in (50.8–76.2 mm) curved metal or plastic tube is inserted into a tracheostomy stoma
or a cricothyrotomy incision.
Tracheal tubes can be used to ensure the adequate exchange
of oxygen and carbon dioxide
, to deliver oxygen in higher concentrations than found in air, or to administer other gases such as helium
, nitric oxide
, nitrous oxide, xenon
, or certain volatile anesthetic agents such as desflurane
, isoflurane
, or sevoflurane
. They may also be used as a route for administration of certain medications such as bronchodilator
s, inhaled corticosteroids, and drugs used in treating cardiac arrest
such as atropine
, epinephrine
, lidocaine
and vasopressin
.
Originally made from latex rubber, most modern endotracheal tubes today are constructed of polyvinyl chloride
. Tubes constructed of silicone rubber
, wire-reinforced silicone rubber or stainless steel
are also available for special applications. For human use, tubes range in size from 2 to 10.5 mm (0.078740157480315 to 0.413385826771654 in) in internal diameter. The size is chosen based on the patient's body size, with the smaller sizes being used for infants and children. Most endotracheal tubes have an inflatable cuff to seal the tracheobronchial tree against leakage of respiratory gases and pulmonary aspiration of gastric contents, blood, secretions and other fluids. Uncuffed tubes are also available, though their use is limited mostly to children (in small children, the cricoid cartilage is the narrowest portion of the airway and usually provides an adequate seal for mechanical ventilation).
In addition to cuffed or uncuffed, preformed endotracheal tubes are also available. The oral and nasal RAE tubes (named after the inventors Ring, Adair and Elwyn) are the most widely used of the preformed tubes.
Various types of endotracheal tubes are available that have endobronchial as well as endotracheal channels (Carlens, White and Robertshaw tubes). These tubes are typically coaxial
, with two separate channels and two separate openings. They incorporate an endotracheal lumen which terminates in the trachea and an endobronchial lumen, the distal tip of which is positioned 1–2 cm into the right or left mainstem bronchus. There is also the Univent tube, which has a single tracheal lumen and an integrated endobronchial blocker. These tubes enable one to ventilate both lungs, or either lung independently. Single-lung ventilation (allowing the lung on the operative side to collapse) can be useful during thoracic surgery
, as it can facilitate the surgeon's view and access to other relevant structures within the thoracic cavity
.
The "armored" endotracheal tubes are cuffed, wire-reinforced silicone rubber tubes. They are much more flexible than polyvinyl chloride tubes, yet they are difficult to compress or kink. This can make them useful for situations in which the trachea is anticipated to remain intubated for a prolonged duration, or if the neck is to remain flexed during surgery. Most armored tubes have a Magill curve, but preformed armored RAE tubes are also available. Another type of endotracheal tube has four small openings just above the inflatable cuff, which can be used for suction of the trachea or administration of intratracheal medications if necessary. Other tubes (such as the Bivona Fome-Cuf tube) are designed specifically for use in laser surgery in and around the airway.
the chest with a stethoscope, and no sound upon listening to the area over the stomach
. Equal bilateral rise and fall of the chest wall will be evident with ventilatory excursions. A small amount of water vapor
will also be evident within the lumen of the tube with each exhalation and there will be no gastric contents in the tracheal tube at any time.
Ideally, at least one of the methods utilized for confirming tracheal tube placement will be a measuring instrument
. Waveform capnography
has emerged as the gold standard
for the confirmation of tube placement within the trachea. Other methods relying on instruments include the use of a colorimetric
end-tidal carbon dioxide detector, a self-inflating esophageal bulb, or an esophageal detection device. The distal tip of a properly positioned tracheal tube will be located in the mid-trachea, roughly 2 cm (0.78740157480315 in) above the bifurcation of the carina; this can be confirmed by chest x-ray. If the tracheal tube is inserted too far into the trachea, the tip will more likely be within the right main bronchus
, because this bronchus has a less acute angle than the left.
s in the airway and poor patient cooperation. Because of this, patients with massive facial injury, complete upper airway obstruction, severe hypoventilation, or profuse upper airway bleeding are poor candidates for fiberoptic intubation. Fiberoptic intubation under general anesthesia typically requires two skilled individuals. Success rates of only 83–87% have been reported using fiberoptic techniques in the emergency department, with significant nasal bleeding occurring in up to 22% of patients. These drawbacks limit the use of fiberoptic bronchoscopy somewhat in urgent and emergent situations.
Personnel experienced in direct laryngoscopy are not always immediately available in certain settings that require emergency tracheal intubation. For this reason, specialized devices have been designed to act as bridges to a definitive airway. Such devices include the laryngeal mask airway, cuffed oropharyngeal
airway and the esophageal-tracheal combitube (Combitube
). Other devices such as rigid stylets, the lightwand (a blind technique) and indirect fiberoptic rigid stylets, such as the Bullard scope, Upsher scope and the WuScope can also be used as alternatives to direct laryngoscopy. Each of these devices have its own unique set of benefits and drawbacks, and none of them is effective under all circumstances.
and intubation (RSI) is a particular method of induction of general anesthesia, commonly employed in emergency operations and other situations where patients are assumed to have a "full stomach". The objective of RSI is to minimize the possibility of regurgitation
and pulmonary aspiration of gastric contents during the induction of general anesthesia and subsequent tracheal intubation. RSI traditionally involves preoxygenating the lungs with a tightly-fitting oxygen mask, followed by the sequential administration of an intravenous sleep-inducing
agent and a rapidly-acting neuromuscular-blocking drug, before intubation of the trachea.
One important difference between RSI and routine tracheal intubation is that the practitioner does not manually assist the ventilation of the lungs after the onset of general anesthesia and cessation of breathing
, until the trachea has been intubated and the cuff has been inflated. Another key feature of RSI is the application of manual pressure to the cricoid cartilage, often referred to as the "Sellick maneuver", prior to instrumentation of the airway and intubation of the trachea.
Since the introduction of RSI, there has been controversy regarding virtually every aspect of this technique, including:
Named for British anesthetist Brian Arthur Sellick (1918–1996) who first described the procedure in 1961, the goal of the Sellick maneuver is to minimize the possibility of regurgitation and pulmonary aspiration of gastric contents. Cricoid pressure has been widely used during RSI for nearly fifty years, despite a lack of compelling evidence to support this practice. The initial article by Sellick was based on a small sample size at a time when high tidal volume
s, head-down positioning
and barbiturate
anesthesia were the rule. Beginning around 2000, a significant body of evidence has accumulated which questions the effectiveness of the Sellick maneuver. The application of cricoid pressure may in fact displace the esophagus laterally instead of compressing it as described by Sellick. Cricoid pressure may also compress the glottis, which can obstruct the view of the laryngoscopist and actually cause a delay in securing the airway.
The Sellick maneuver is often confused with the "BURP" (Backwards Upwards Rightwards Pressure) maneuver. While both of these involve digital pressure to the anterior aspect (front) of the laryngeal apparatus, the purpose of the latter is to improve the view of the glottis during laryngoscopy and tracheal intubation, rather than to prevent regurgitation.
A cricothyrotomy is an incision made through the skin and cricothyroid membrane
to establish a patent airway during certain life-threatening situations, such as airway obstruction by a foreign body, angioedema, or massive facial trauma. A cricothyrotomy is nearly always performed as a last resort in cases where orotracheal and nasotracheal intubation are impossible or contraindicated. Cricothyrotomy is easier and quicker to perform than tracheotomy, does not require manipulation of the cervical spine and is associated with fewer complications.
The quickest and easiest method to perform this technique is the needle cricothyrotomy (also referred to as a percutaneous
dilational cricothyrotomy), in which a large-bore (12–14 gauge
) intravenous catheter
is used to puncture the cricothyroid membrane. Oxygen can then be administered through this catheter via jet insufflation. However, while needle cricothyrotomy may be life-saving in extreme circumstances, this technique is only intended to be a temporizing measure until a definitive airway can be established. While needle cricothyrotomy can provide adequate oxygenation, the small diameter of the cricothyrotomy catheter is insufficient for elimination of carbon dioxide (ventilation). After one hour of apneic oxygenation through a needle cricothyrotomy, one can expect a PaCO2
of greater than 250 mm Hg and an arterial pH
of less than 6.72, despite an oxygen saturation of 98% or greater. A more definitive airway can be established by performing a surgical cricothyrotomy, in which a 5 to 6 mm (0.196850393700787 to 0.236220472440945 in) endotracheal tube or tracheostomy tube can be inserted through a larger incision.
Several manufacturers market prepackaged cricothyrotomy kits, which enable one to use either a wire-guided percutaneous dilational (Seldinger) technique, or the classic surgical technique to insert a polyvinylchloride catheter through the cricothyroid membrane. The kits may be stocked in hospital emergency departments and operating suites, as well as ambulances and other selected pre-hospital
settings.
Tracheotomy consists of making an incision on the front of the neck and opening a direct airway through an incision in the trachea. The resulting opening
can serve independently as an airway or as a site for a tracheostomy tube to be inserted; this tube allows a person to breathe without the use of their nose or mouth. The opening may be made by a scalpel or a needle (referred to as surgical and percutaneous techniques respectively) and both techniques are widely used in current practice. In order to limit the risk of damage to the recurrent laryngeal nerve
s (the nerves that control the voicebox
), the tracheotomy is performed as high in the trachea as possible. If only one of these nerves is damaged, the patient's voice may be impaired (dysphonia
); if both of the nerves are damaged, the patient will be unable to speak (aphonia
). In the acute setting, indications for tracheotomy are similar to those for cricothyrotomy. In the chronic setting, indications for tracheotomy include the need for long-term mechanical ventilation and removal of tracheal secretions (e.g., comatose patients, or extensive surgery involving the head and neck).
patient. The differences, which are quite significant in infants, gradually disappear as the human body approaches a mature age and body mass index
.
For infants and young children, orotracheal intubation is easier than the nasotracheal route. Nasotracheal intubation carries a risk of dislodgement of adenoids and nasal bleeding. Despite the greater difficulty, nasotracheal intubation route is preferable to orotracheal intubation in children undergoing intensive care and requiring prolonged intubation because this route allows a more secure fixation of the tube. As with adults, there are a number of devices specially designed for assistance with difficult tracheal intubation in children. Confirmation of proper position of the tracheal tube is accomplished as with adult patients.
Because the airway of a child is narrow, a small amount of glottic or tracheal swelling
can produce critical obstruction. Inserting a tube that is too large relative to the diameter of the trachea can cause swelling. Conversely, inserting a tube that is too small can result in inability to achieve effective positive pressure ventilation due to retrograde escape of gas through the glottis and out the mouth and nose (often referred to as a "leak" around the tube). An excessive leak can usually be corrected by inserting a larger tube or a cuffed tube.
The tip of a correctly positioned tracheal tube will be in the mid-trachea, between the collarbones
on an anteroposterior chest radiograph. The correct diameter of the tube is that which results in a small leak at a pressure of about 25 cm (9.8 in) of water. The appropriate inner diameter for the endotracheal tube is estimated to be roughly the same diameter as the child's little finger. The appropriate length for the endotracheal tube can be estimated by doubling the distance from the corner of the child's mouth to the ear canal
. For premature infants 2.5 mm (0.0984251968503937 in) internal diameter is an appropriate size for the tracheal tube. For infants of normal gestational age
, 3 mm (0.118110236220472 in) internal diameter is an appropriate size. For normally nourished children 1 year of age and older, the following formulae estimate the proper diameter and depth of insertion for tracheal tubes:
of the patient and performing a physical examination
, the results of which can be scored against one of several classification systems. The proposed surgical procedure (e.g., surgery involving the head and neck, or bariatric surgery
) may lead one to anticipate difficulties with intubation. Many individuals have unusual airway anatomy, such as those who have limited movement of their neck or jaw, or those who have tumors, deep swelling due to injury
or to allergy
, developmental abnormalities of the jaw, or excess fatty tissue of the face and neck. Using conventional laryngoscopic techniques, intubation of the trachea can be difficult or even impossible in such patients. This is why all persons performing tracheal intubation must be familiar with alternative techniques of securing the airway. Use of the flexible fiberoptic bronchoscope and similar devices has become among the preferred techniques in the management of such cases. However, these devices require a different skill set than that employed for conventional laryngoscopy and are expensive to purchase, maintain and repair.
When taking the patient's medical history, the subject is questioned about any significant signs
or symptom
s, such as difficulty in speaking
or difficulty in breathing
. These may suggest obstructing lesion
s in various locations within the upper airway, larynx
, or tracheobronchial tree. A history of previous surgery (e.g., previous cervical fusion
), injury, radiation therapy
, or tumor
s involving the head, neck and upper chest
can also provide clues to a potentially difficult intubation. Previous experiences with tracheal intubation, especially difficult intubation, intubation for prolonged duration (e.g., intensive care unit) or prior tracheotomy are also noted.
A detailed physical examination
of the airway is important, particularly:
Many classification systems have been developed in an effort to predict difficulty of tracheal intubation, including the Cormack-Lehane grading system, the Intubation Difficulty Scale (IDS), and the Mallampati score
. The Mallampati score is drawn from the observation that the size of the base of the tongue
influences the difficulty of intubation. It is determined by looking at the anatomy of the mouth, and in particular the visibility of the base of palatine uvula, faucial pillars and the soft palate
. Although such medical scoring systems may aid in the evaluation of patients, no single score or combination of scores can be trusted to specifically detect all and only those patients who are difficult to intubate. Furthermore, one study of experienced anesthesiologists, on the widely used Cormack–Lehane classification system, found they did not score the same patients consistently over time, and that only 25% could correctly define all four grades of the widely used Cormack–Lehane classification system. Under certain emergency circumstances (e.g., severe head trauma or suspected cervical spine injury), it may be impossible to fully utilize these the physical examination and the various classification systems to predict the difficulty of tracheal intubation. In such cases, alternative techniques of securing the airway must be readily available.
Four anatomic features must be present for orotracheal intubation to be straightforward: adequate mouth opening (full range of motion of the temporomandibular joint), sufficient pharyngeal space (determined by examining the hypopharynx), sufficient submandibular space (distance between the thyroid cartilage and the chin, the space into which the tongue must be displaced in order for the larygoscopist to view the glottis), and adequate extension of the cervical spine at the atlanto-occipital joint. If any of these variables is in any way compromised, intubation should be expected to be difficult.
Minor complications are common after laryngoscopy and insertion of an orotracheal tube. These are typically of short duration, such as sore throat, lacerations of the lips or gums
or other structures within the upper airway, chipped, fractured or dislodged teeth, nasal injury, Other complications which are common but potentially more serious include accelerated
or irregular
heartbeat, high blood pressure
, elevated intracranial
and introcular
pressure, and bronchospasm
.
More serious complications include laryngospasm
, perforation of the trachea
or esophagus
, pulmonary aspiration of gastric contents or other foreign bodies, fracture or dislocation of the cervical spine, temporomandibular joint
or arytenoid cartilage
s, decreased oxygen content, elevated arterial carbon dioxide
, and vocal cord weakness
. In addition to these complications, tracheal intubation via the nasal route carries a risk of dislodgement of adenoids and potentially severe nasal bleeding. Newer technologies such as flexible fiberoptic laryngoscopy have fared better in reducing the incidence of some of these complications, though the most frequent cause of intubation trauma remains a lack of skill on the part of the laryngoscopist.
Complications may also be severe and long-lasting or permanent, such as vocal cord damage, esophageal perforation and retropharyngeal abscess
, bronchial intubation, or nerve injury. They may even be immediately life-threatening, such as laryngospasm and negative pressure pulmonary edema
(fluid in the lungs), aspiration, unrecognized esophageal intubation, or accidental disconnection or dislodgement of the tracheal tube. Potentially fatal complications more often associated with prolonged intubation and/or tracheotomy include abnormal communication between the trachea and nearby structures such as the innominate artery
(tracheoinnominate fistula
) or esophagus (tracheoesophageal fistula
). Other significant complications include airway obstruction due to loss of tracheal rigidity
, ventilator-associated pneumonia
and narrowing
of the glottis or trachea. The cuff pressure is monitored carefully in order to avoid complications from over-inflation, many of which can be traced to excessive cuff pressure restricting the blood supply to
the tracheal mucosa. A 2000 Spanish study of bedside percutaneous tracheotomy reported overall complication rates of 10–15% and procedural mortality of 0%, which is comparable to those of other series reported in the literature from the Netherlands and the United States.
Inability to secure the airway, with subsequent failure of oxygenation and ventilation is a life-threatening complication which if not immediately corrected leads to hypoxia, brain damage, cardiovascular collapse
, and death. When performed improperly, the associated complications (e.g., unrecognized esophageal intubation) may be rapidly fatal. Without adequate training and experience, the incidence of such complications is unacceptably high. For example, among paramedic
s in several United States urban communities, unrecognized esophageal or hypopharyngeal
intubation has been reported to be 6% to 25%. Among providers at the basic emergency medical technician
(EMT-B) level, reported success rates for tracheal intubation are as low as 51%. In one study, nearly half of patients with misplaced tracheal tubes died in the emergency room. Because of this, recent editions of the American Heart Association
's Guidelines for Cardiopulmonary Resuscitation have de-emphasized the role of tracheal intubation in favor of other airway management techniques such as bag-valve-mask ventilation, the laryngeal mask airway and the Combitube.
One complication—unintentional and unrecognized intubation of the esophagus—is both common (as frequent as 25% in the hands of inexperienced personnel) and likely to result in a deleterious or even fatal outcome. In such cases, oxygen is inadvertently administered to the stomach, from where it cannot be taken up by the circulatory system
, instead of the lungs. If this situation is not immediately identified and corrected, death will ensue from cerebral and cardiac anoxia.
Of 4,460 claims in the American Society of Anesthesiologists
(ASA) Closed Claims Project database, 266 (approximately 6%) were for airway injury. Of these 266 cases, 87% of the injuries were temporary, 5% were permanent or disabling, and 8% resulted in death. Difficult intubation, age older than 60 years, and female gender were associated with claims for perforation of the esophagus or pharynx. Early signs of perforation were present in only 51% of perforation claims, whereas late sequelae occurred in 65%.
es include the laryngeal mask airway, i-gel, cuffed oropharyngeal airway, continuous positive airway pressure (CPAP mask), nasal BiPAP mask, simple face mask, and nasal cannula.
General anesthesia is often administered without tracheal intubation in selected cases where the procedure is brief in duration, or procedures where the depth of anesthesia is not sufficient to cause significant compromise in ventilatory function. Even for longer duration or more invasive procedures, a general anesthetic may be administered without intubating the trachea, provided that patients are carefully selected, and the risk-benefit ratio
is favorable (i.e., the risks associated with an unprotected airway are believed to be less than the risks of intubating the trachea).
The earliest known depiction of a tracheotomy is found on two Egyptian tablets dating back to around 3600 BC. The 110-page Ebers Papyrus
, an Egyptian medical papyrus which dates to roughly 1550 BC, also makes reference to the tracheotomy. Tracheotomy was described in the Rigveda
, a Sanskrit
text of ayurvedic medicine
written around 2000 BC in ancient India
. The Sushruta Samhita
from around 400 BC is another text from the Indian subcontinent on ayurvedic medicine and surgery that mentions tracheotomy. Asclepiades of Bithynia
(c. 124–40 BC) is often credited as being the first physician to perform a non-emergency tracheotomy. Galen
of Pergamon
(AD 129–199) clarified the anatomy of the trachea and was the first to demonstrate that the larynx generates the voice. In one of his experiments, Galen used bellows to inflate the lungs of a dead animal. Ibn Sīnā
(980–1037) described the use of tracheal intubation to facilitate breathing in 1025 in his 14-volume medical encyclopedia, The Canon of Medicine
. In the 12th century medical textbook Al-Taisir, Ibn Zuhr
(1092–1162)—also known as Avenzoar—of Al-Andalus
provided a correct description of the tracheotomy operation.
The first detailed descriptions of tracheal intubation and subsequent artificial respiration
of animals were from Andreas Vesalius (1514–1564) of Brussels. In his landmark book published in 1543, De humani corporis fabrica
, he described an experiment in which he passed a reed
into the trachea of a dying animal whose thorax had been opened and maintained ventilation by blowing into the reed intermittently. Antonio Musa Brassavola
(1490–1554) of Ferrara
successfully treated a patient suffering from peritonsillar abscess
by tracheotomy. Brassavola published his account in 1546; this operation has been identified as the first recorded successful tracheotomy, despite the many previous references to this operation. Towards the end of the 16th century, Hieronymus Fabricius
(1533–1619) described a useful technique for tracheotomy in his writings, although he had never actually performed the operation himself. Fabricius was the first to introduce the idea of a tracheostomy tube. In 1620 the French surgeon Nicholas Habicot (1550–1624) published a report of four successful tracheotomies. In 1714, anatomist Georg Detharding (1671–1747) of the University of Rostock
performed a tracheotomy on a drowning victim.
Despite the many recorded instances of its use since antiquity
, it was not until the early 19th century that the tracheotomy finally began to be recognized as a legitimate means of treating severe airway obstruction. In 1852, French physician Armand Trousseau
(1801–1867) presented a series of 169 tracheotomies to the Académie Impériale de Médecine
. 158 of these were performed for the treatment of croup
, and 11 were performed for "chronic maladies of the larynx". Between 1830 and 1855, more than 350 tracheotomies were performed in Paris, most of them at the Hôpital des Enfants Malades
, a public hospital
, with an overall survival rate of only 20–25%. This compares with 58% of the 24 patients in Trousseau's private practice, who fared better due to greater postoperative care.
In 1871, the German surgeon Friedrich Trendelenburg
(1844–1924) published a paper describing the first successful elective human tracheotomy to be performed for the purpose of administration of general anesthesia. In 1888, Sir Morell Mackenzie
(1837–1892) published a book discussing the indications for tracheotomy. In the early 20th century, tracheotomy became a life-saving treatment for patients afflicted with paralytic poliomyelitis
who required mechanical ventilation. In 1909, Philadelphia laryngologist Chevalier Jackson
(1865–1958) described a technique for tracheotomy that is used to this day.
Laryngoscopy and non-surgical techniques
In 1854, a Spanish singing teacher
named Manuel García
(1805–1906) became the first man to view the functioning glottis in a living human. In 1858, French pediatrician Eugène Bouchut
(1818–1891) developed a new technique for non-surgical orotracheal intubation to bypass laryngeal obstruction resulting from a diphtheria
-related pseudomembrane. In 1880, Scottish surgeon William Macewen
(1848–1924) reported on his use of orotracheal intubation as an alternative to tracheotomy to allow a patient with glottic edema to breathe, as well as in the setting of general anesthesia with chloroform
. In 1895, Alfred Kirstein (1863–1922) of Berlin first described direct visualization of the vocal cords, using an esophagoscope he had modified for this purpose; he called this device an autoscope.
In 1913, Chevalier Jackson was the first to report a high rate of success for the use of direct laryngoscopy as a means to intubate the trachea. Jackson introduced a new laryngoscope blade that incorporated a component that the operator could slide out to allow room for passage of an endotracheal tube or bronchoscope. Also in 1913, New York surgeon Henry H. Janeway (1873–1921) published results he had achieved using a laryngoscope he had recently developed. Another pioneer in this field was Sir Ivan Whiteside Magill
(1888–1986), who developed the technique of awake blind nasotracheal intubation, the Magill forceps, the Magill laryngoscope blade, and several apparati for the administration of volatile anesthetic agents. The Magill curve of an endotracheal tube is also named for Magill. Sir Robert Reynolds Macintosh
(1897–1989) introduced a curved laryngoscope blade in 1943; the Macintosh blade remains to this day the most widely used laryngoscope blade for orotracheal intubation.
Between 1945 and 1952, optical engineers
built upon the earlier work of Rudolph Schindler (1888–1968), developing the first gastrocamera. In 1964, optical fiber
technology was applied to one of these early gastrocameras to produce the first flexible fiberoptic endoscope. Initially used in upper GI endoscopy
, this device was first used for laryngoscopy and tracheal intubation by Peter Murphy, an English anesthetist, in 1967. The concept of using a stylet for replacing or exchanging orotracheal tubes was introduced by Finucane and Kupshik in 1978, using a central venous catheter
.
By the mid-1980s, the flexible fiberoptic bronchoscope had become an indispensable instrument within the pulmonology and anesthesia communities. The digital revolution
of the 21st century has brought newer technology to the art and science of tracheal intubation. Several manufacturers have developed video laryngoscopes which employ digital technology such as the CMOS
active pixel sensor
(CMOS APS) to generate a view of the glottis so that the trachea may be intubated.
Intubation
Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic or rubber tube into the trachea to maintain an open airway or to serve as a conduit through which to administer certain drugs...
, is the placement of a flexible plastic or rubber tube
Catheter
In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. Catheters thereby allow drainage, administration of fluids or gases, or access by surgical instruments. The process of inserting a catheter is catheterization...
into the trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
(windpipe) to maintain an open airway
Airway
The pulmonary airway comprises those parts of the respiratory system through which air flows, conceptually beginning at the nose and mouth, and terminating in the alveoli...
or to serve as a conduit through which to administer certain drugs. It is frequently performed in critically injured, ill or anesthetized patients to facilitate ventilation
Ventilation (physiology)
In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...
of the lungs, including mechanical ventilation
Mechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
, and to prevent the possibility of asphyxia
Asphyxia
Asphyxia or asphyxiation is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs...
tion or airway obstruction. The most widely used route is orotracheal, in which an endotracheal tube
Tracheal tube
A tracheal tube is a catheter that is inserted into the trachea in order for the primary purpose of establishing and maintaining a patent airway and to ensure the adequate exchange of oxygen and carbon dioxide. Many different types of tracheal tubes are available, suited for different specific...
is passed through the mouth and vocal apparatus
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
into the trachea. In a nasotracheal procedure, an endotracheal tube is passed through the nose and vocal apparatus into the trachea. Other methods of intubation involve surgery and include the cricothyrotomy
Cricothyrotomy
A cricothyrotomy is an incision made through the skin and cricothyroid membrane to establish a patent airway during certain life-threatening situations, such as airway obstruction by a foreign body, angioedema, or massive...
(used almost exclusively in emergency circumstances) and the tracheotomy
Tracheotomy
Among the oldest described surgical procedures, tracheotomy consists of making an incision on the anterior aspect of the neck and opening a direct airway through an incision in the trachea...
, used primarily in situations where a prolonged need for airway support is anticipated, surgical methods are also used in emergency situations when conventional endotracheal intubation is not possible.
Because it is an invasive
Invasiveness of surgical procedures
There are three main categories which describe the invasiveness of surgical procedures. These are: non-invasive procedures, minimally invasive procedures, and invasive procedures ....
and extremely uncomfortable medical procedure
Medical procedure
A medical procedure is a course of action intended to achieve a result in the care of persons with health problems.A medical procedure with the intention of determining, measuring or diagnosing a patient condition or parameter is also called a medical test...
, intubation is usually performed after administration of general anesthesia
General anaesthesia
General anaesthesia is a state of unconsciousness and loss of protective reflexes resulting from the administration of one or more general anaesthetic agents...
and a neuromuscular-blocking drug
Neuromuscular-blocking drug
Neuromuscular-blocking drugs block neuromuscular transmission at the neuromuscular junction, causing paralysis of the affected skeletal muscles. This is accomplished either by acting presynaptically via the inhibition of acetylcholine synthesis or release or by acting postsynaptically at the...
. It can however be performed in the awake patient with local
Local anesthesia
Local anesthesia is any technique to induce the absence of sensation in part of the body, generally for the aim of inducing local analgesia, that is, local insensitivity to pain, although other local senses may be affected as well. It allows patients to undergo surgical and dental procedures with...
or topical anesthesia
Topical anesthetic
A topical anesthetic is a local anesthetic that is used to numb the surface of a body part. They can be used to numb any area of the skin as well as the front of the eyeball, the inside of the nose, ear or throat, the anus and the genital area. Topical anesthetics are available in creams,...
, or in an emergency without any anesthesia at all. Intubation is normally facilitated by using a conventional laryngoscope
Laryngoscopy
Laryngoscopy is a medical procedure that is used to obtain a view of the vocal folds and the glottis. Laryngoscopy may be performed to facilitate tracheal intubation during general anesthesia or cardiopulmonary resuscitation or for procedures on the larynx or other parts of the upper...
, flexible fiberoptic bronchoscope
Fiberscope
A fiberscope is a flexible fiber optic bundle with an eyepiece at one end, and a lens at the other. It is used for inspection work, often to examine small components in tightly packed equipment, when the inspector cannot easily access the part requiring inspection.The lens is often a wide-angle...
or video laryngoscope to identify the glottis
Glottis
The glottis is defined as the combination of the vocal folds and the space in between the folds .-Function:...
, though other devices and techniques are available. After the trachea has been intubated, a balloon cuff is typically inflated just above the far end of the tube to help secure it in place, to prevent leakage of respiratory gases, and to protect the tracheobronchial tree
Tracheobronchial tree
The tracheobronchial tree is the structure from the trachea, bronchi, and bronchioles that forms the airways that supply air to the lungs. It is within the neck and the chest. The structure looks like a tree because the trachea splits into the right and left mainstem bronchi, which "branch" into...
from receiving undesirable material
Pulmonary aspiration
Pulmonary aspiration is the entry of material from the oropharynx or gastrointestinal tract into the larynx and lower respiratory tract...
such as stomach acid. The tube is then secured to the face or neck and connected to a T-piece, anesthesia breathing circuit, bag valve mask
Bag valve mask
A bag valve mask is a hand-held device used to provide positive pressure ventilation to a patient who is not breathing or who is breathing inadequately. The device is a normal part of a resuscitation kit for trained professionals, such as ambulance crew...
device, or a mechanical ventilator
Medical ventilator
A medical ventilator can be defined as any machine designed to mechanically move breatheable air into and out of the lungs, to provide the mechanism of breathing for a patient who is physically unable to breathe, or breathing insufficiently....
. Once there is no longer a need for ventilatory assistance and/or protection of the airway, the tracheal tube is removed; this is referred to as extubation of the trachea (or decannulation, in the case of a surgical airway such as a cricothyrotomy or a tracheotomy).
For centuries, tracheotomy was considered the only reliable method for intubation of the trachea. However, because only a minority of patients survived the operation, physicians undertook tracheotomy only as a last resort, on patients who were nearly dead. It was not until the late 19th century however that advances in anatomy
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
and physiology
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
, as well an appreciation of the germ theory of disease
Germ theory of disease
The germ theory of disease, also called the pathogenic theory of medicine, is a theory that proposes that microorganisms are the cause of many diseases...
, had improved the outcome of this operation to the point that it could be considered an acceptable treatment option. Also at that time, advances in endoscopic
Endoscopy
Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope , an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ...
instrumentation had improved to such a degree that direct laryngoscopy had become a viable means to secure the airway by the non-surgical orotracheal route. By the mid-20th century, the tracheotomy as well as endoscopy and non-surgical tracheal intubation had evolved from rarely employed procedures to becoming essential components of the practices of anesthesiology
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
, critical care medicine, emergency medicine
Emergency medicine
Emergency medicine is a medical specialty in which physicians care for patients with acute illnesses or injuries which require immediate medical attention. While not usually providing long-term or continuing care, emergency medicine physicians diagnose a variety of illnesses and undertake acute...
, gastroenterology
Gastroenterology
Gastroenterology is the branch of medicine whereby the digestive system and its disorders are studied. The name is a combination of three Ancient Greek words gaster , enteron , and logos...
, laryngology
Laryngology
Laryngology is that branch of medicine which deals with disorders, diseases and injuries of the vocal apparatus, especially the larynx. Common conditions addressed by laryngologists include vocal fold nodules and cysts, laryngeal cancer, spasmodic dysphonia, laryngopharyngeal reflux, papillomas,...
, pulmonology
Pulmonology
In medicine, pulmonology is the specialty that deals with diseases of the respiratory tract and respiratory disease. It is called chest medicine and respiratory medicine in some countries and areas...
and surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
.
Tracheal intubation can be associated with minor complications
Complication (medicine)
Complication, in medicine, is an unfavorable evolution of a disease, a health condition or a medical treatment. The disease can become worse in its severity or show a higher number of signs, symptoms or new pathological changes, become widespread throughout the body or affect other organ systems. A...
such as broken teeth or lacerations of the tissues
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
of the upper airway
Human pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
. It can also be associated with potentially fatal complications such as pulmonary aspiration of stomach contents which can result in a severe and sometimes fatal chemical aspiration pneumonitis
Aspiration pneumonia
Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials into the bronchial tree, usually oral or gastric contents...
, or unrecognized intubation of the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
which can lead to potentially fatal anoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
. Because of this, the potential for difficulty or complications due to the presence of unusual airway anatomy or other uncontrolled variables is carefully evaluated before undertaking tracheal intubation. Alternative strategies for securing the airway must always be readily available. The incidence of serious complications is unacceptably high when undertaken by practitioners lacking adequate training and experience.
Indications
Tracheal intubation is indicatedIndication (medicine)
In medicine, an indication is a valid reason to use a certain test, medication, procedure, or surgery. The opposite of indication is contraindication.-Drugs:...
in a variety of situations when illness or a medical procedure prevents a person from maintaining a clear airway, breathing, and oxygenating
Oxygenation (medical)
Oxygenation occurs when oxygen molecules enter the tissues of the body. For example, blood is oxygenated in the lungs, where oxygen molecules travel from the air and into the blood...
the blood. In these circumstances, oxygen supplementation
Oxygen therapy
Oxygen therapy is the administration of oxygen as a medical intervention, which can be for a variety of purposes in both chronic and acute patient care...
using a simple face mask
Simple face mask
The simple face mask is a basic disposable mask, made of clear plastic, to provide oxygen therapy for patients who are experiencing conditions such as chest pain , dizziness, and minor hemorrhages. It is often set to deliver oxygen between 6-10 litres per minute...
is inadequate.
Depressed level of consciousness
Perhaps the most common indication for tracheal intubation is for the placement of a conduit through which nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...
or volatile anesthetics may be administered. General anesthetic agents
General anaesthetic
A general anaesthetic is a drug that brings about a reversible loss of consciousness. These drugs are generally administered by an anaesthesia provider to induce or maintain general anaesthesia to facilitate surgery...
, opioid
Opioid
An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...
s, and neuromuscular-blocking drugs may diminish
Hypoventilation
In medicine, hypoventilation occurs when ventilation is inadequate to perform needed gas exchange...
or even abolish
Apnea
Apnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
the respiratory drive
Control of respiration
Control of ventilation refers to the physiological mechanisms involved in the control of physiologic ventilation. Gas exchange primarily controls the rate of respiration.The most important function of breathing is gas exchange...
. Although it is not the only means to maintain a patent airway during general anesthesia, intubation of the trachea provides the most reliable means of oxygenation and ventilation
Ventilation (physiology)
In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...
and the greatest degree of protection against regurgitation and pulmonary aspiration.
Damage to the brain (such as from a massive stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, non-penetrating head injury, intoxication or poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
ing) may result in a depressed level of consciousness
Altered level of consciousness
An altered level of consciousness is any measure of arousal other than normal. Level of consciousness is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousness may be classed as lethargy; someone in this state can be...
. When this becomes severe to the point of stupor
Stupor
Stupor is the lack of critical cognitive function and level of consciousness wherein a sufferer is almost entirely unresponsive and only responds to base stimuli such as pain. This is often mistaken for delirium and treated with Haldol and or other anti-psychotic drugs...
or coma
Coma
In medicine, a coma is a state of unconsciousness, lasting more than 6 hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light or sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. A person in a state of coma is described as...
(defined as a score on the Glasgow Coma Scale
Glasgow Coma Scale
Glasgow Coma Scale or GCS is a neurological scale that aims to give a reliable, objective way of recording the conscious state of a person for initial as well as subsequent assessment...
of less than 8), dynamic collapse of the extrinsic muscles of the airway can obstruct the airway, impeding the free flow of air into the lungs. Furthermore, protective airway reflexes such as cough
Cough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
ing and swallowing
Swallowing
Swallowing, known scientifically as deglutition, is the process in the human or animal body that makes something pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. If this fails and the object goes through the trachea, then choking or pulmonary aspiration...
may be diminished or absent. Tracheal intubation is often required to restore patency (the relative absence of blockage) of the airway and protect the tracheobronchial tree from pulmonary aspiration of gastric contents.
Hypoxemia
Intubation may be necessary for a patient with decreased oxygen content
Hypoxemia
Hypoxemia is generally defined as decreased partial pressure of oxygen in blood, sometimes specifically as less than or causing hemoglobin oxygen saturation of less than 90%.-Distinction from anemia and hypoxia:...
and oxygen saturation
Oxygen saturation
Oxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...
of the blood caused when their breathing is inadequate (hypoventilation
Hypoventilation
In medicine, hypoventilation occurs when ventilation is inadequate to perform needed gas exchange...
), suspended (apnea
Apnea
Apnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
), or when the lungs are unable to sufficiently transfer gasses to the blood
Diffusion capacity
In biology, diffusion capacity is a measurement of the lung's ability to transfer gases. Oxygen uptake may be limited by diffusion in circumstances of low ambient oxygen or high pulmonary blood flow...
. Such patients, who may be awake and alert, are typically critically ill with a multisystem disease or multiple severe injuries. Examples of such conditions include cervical spine injury
Spinal cord injury
A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...
, multiple rib fractures
Flail chest
A flail chest is a life-threatening medical condition that occurs when a segment of the rib cage breaks under extreme stress and becomes detached from the rest of the chest wall. It occurs when multiple adjacent ribs are broken in multiple places, separating a segment, so a part of the chest wall...
, severe pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
, acute respiratory distress syndrome
Acute respiratory distress syndrome
Acute respiratory distress syndrome , also known as respiratory distress syndrome or adult respiratory distress syndrome is a serious reaction to various forms of injuries to the lung....
(ARDS), or near-drowning
Drowning
Drowning is death from asphyxia due to suffocation caused by water entering the lungs and preventing the absorption of oxygen leading to cerebral hypoxia....
. Specifically, intubation is considered if the arterial
Arterial blood gas
An arterial blood gas is a blood test that is performed using blood from an artery. It involves puncturing an artery with a thin needle and syringe and drawing a small volume of blood. The most common puncture site is the radial artery at the wrist, but sometimes the femoral artery in the groin or...
partial pressure
Partial pressure
In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
of oxygen (PaO2) is less than 60 millimeters of mercury
Torr
The torr is a non-SI unit of pressure with the ratio of 760 to 1 standard atmosphere, chosen to be roughly equal to the fluid pressure exerted by a millimetre of mercury, i.e., a pressure of 1 torr is approximately equal to 1 mmHg...
(mm Hg) while breathing an inspired O2 concentration (FIO2
FiO2
FiO2, in the field of medicine, is the fraction of inspired oxygen in a gas mixture.The FiO2 is expressed as a number from 0 to 1 .The FiO2 of normal room air is 0.21 ....
) of 50% or greater. In patients with elevated arterial carbon dioxide
Hypercapnia
Hypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...
, an arterial partial pressure of CO2 (PaCO2) greater than 45 mm Hg in the setting of acidemia
Acidosis
Acidosis is an increased acidity in the blood and other body tissue . If not further qualified, it usually refers to acidity of the blood plasma....
would prompt intubation, especially if a series of measurements demonstrate a worsening respiratory acidosis
Respiratory acidosis
Respiratory acidosis is a medical condition in which decreased ventilation causes increased blood carbon dioxide concentration and decreased pH ....
. Regardless of the laboratory values, these guidelines are always interpreted in the clinical context.
Airway obstruction
Actual or impending airway obstruction is a common indication for intubation of the trachea. Life-threatening airway obstruction may occur when a foreign body
Foreign body
A foreign body is any object originating outside the body. In machinery, it can mean any unwanted intruding object.Most references to foreign bodies involve propulsion through natural orifices into hollow organs....
becomes lodged in the airway; this is especially common in infants and toddlers. Severe blunt
Blunt trauma
In medical terminology, blunt trauma, blunt injury, non-penetrating trauma or blunt force trauma refers to a type of physical trauma caused to a body part, either by impact, injury or physical attack; the latter usually being referred to as blunt force trauma...
or penetrating
Penetrating trauma
Penetrating trauma is an injury that occurs when an object pierces the skin and enters a tissue of the body, creating an open wound. In blunt, or non-penetrating trauma, there may be an impact, but the skin is not necessarily broken. The penetrating object may remain in the tissues, come back out...
injury to the face or neck may be accompanied by swelling
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
and an expanding hematoma
Hematoma
A hematoma, or haematoma, is a localized collection of blood outside the blood vessels, usually in liquid form within the tissue. This distinguishes it from an ecchymosis, which is the spread of blood under the skin in a thin layer, commonly called a bruise...
, or injury to the larynx, trachea or bronchi
Tracheobronchial injury
Tracheobronchial injury is damage to the tracheobronchial tree . It can result from blunt or penetrating trauma to the neck or chest, inhalation of harmful fumes or smoke, or aspiration of liquids or objects.Though rare, TBI is a serious condition; it may cause obstruction of the airway with...
. Airway obstruction is also common in people who have suffered smoke inhalation
Smoke inhalation
Smoke inhalation is the primary cause of death in victims of indoor fires.Smoke inhalation injury refers to injury due to inhalation or exposure to hot gaseous products of combustion. This can cause serious respiratory complications....
or burns within close to the airway or epiglottitis
Epiglottitis
Epiglottitis is an inflammation of the epiglottis - the flap that sits at the base of the tongue, which keeps food from going into the trachea . Due to its place in the airway, swelling of this structure can interfere with breathing and constitutes a medical emergency...
caused by infection. Sustained generalized seizure activity and angioedema
Angioedema
Angioedema or Quincke's edema is the rapid swelling of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis...
are other common causes of life-threatening airway obstruction which may require tracheal intubation to secure the airway.
Manipulation of the airway
Diagnostic or therapeutic manipulation of the airway (such as bronchoscopy, laser therapy
Laser medicine
Laser medicine is the use of various types of lasers in medical diagnosis, treatment, or therapy. Types of lasers used in medicine include in principle any laser design, especially:* CO2 lasers* diode lasers* dye lasers* excimer lasers* fiber lasers...
or stent
Stent
In the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...
ing of the bronchi
Bronchus
A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles....
) may intermittently interfere with the ability to breathe; intubation may be necessary in such situations.
Laryngoscopes
The vast majority of tracheal intubations involve the use of a viewing instrument of one type or another. The modern conventional laryngoscope consists of a handle containing batteries that power a light and a set of interchangeable bladeBlade
A blade is that portion of a tool, weapon, or machine with a cutting edge and/or a pointed tip that is designed to cut and/or puncture, stab, slash, chop, slice, thrust, or scrape animate or inanimate surfaces or materials...
s, which are either straight or curved. This device is designed to allow the laryngoscopist to directly view the larynx. Due to the widespread availability of such devices, the technique of blind digital intubation of the trachea is rarely practiced today, although it may still be useful in certain emergency situations, such as natural or man-made disasters.
The decision to use a straight or curved laryngoscope blade depends partly on the specific anatomical features of the airway, and partly on the personal experience and preference of the laryngoscopist. The Macintosh
Robert Reynolds Macintosh
Sir Robert Reynolds Macintosh was a New Zealand-born anaesthetist. He was the first Professor of Anaesthetics outside United States.-Early life:...
blade is the most widely used curved laryngoscope blade, while the Miller blade is the most popular style of straight blade. Both Miller and Macintosh laryngoscope blades are available in sizes 0 (infant) through 4 (large adult). There are many other styles of straight and curved blades, with accessories such as mirrors for enlarging the field of view and even ports for the administration of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
. These specialty blades are primarily designed for use by anesthetist
Anesthesiologist
An anesthesiologist or anaesthetist is a physician trained in anesthesia and peri-operative medicine....
s and otolaryngologists
Otolaryngology
Otolaryngology or ENT is the branch of medicine and surgery that specializes in the diagnosis and treatment of ear, nose, throat, and head and neck disorders....
, most commonly in the operating room.
Fiberoptic
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
layngoscopes have become increasingly available since the 1990s. In contrast to the conventional laryngoscope, these devices allow the laryngoscopist to indirectly view the larynx. This provides a significant advantage in situations where the operator needs to see around an acute bend in order to visualize the glottis, and deal with otherwise difficult intubations. Video laryngoscopes are specialized fiberoptic layngoscopes that use a digital video camera sensor
Active pixel sensor
An active-pixel sensor is an image sensor consisting of an integrated circuit containing an array of pixel sensors, each pixel containing a photodetector and an active amplifier. There are many types of active pixel sensors including the CMOS APS used most commonly in cell phone cameras, web...
to allow the operator to view the glottis and larynx on a video monitor. Other "noninvasive" devices which can be employed to assist in tracheal intubation are the laryngeal mask airway
Laryngeal mask airway
The laryngeal mask airway is a supraglottic airway device invented by Archie Brain, a British anaesthetist.-Description:Laryngeal masks consist of a tube with an inflatable cuff that is inserted into the pharynx. Laryngeal mask airways come in a variety of sizes ranging from large adult to infant...
(used as a conduit for endotracheal tube placement) and the AirTraq.
Stylets
An intubating stylet is a malleable metal wire designed to be inserted into the endotracheal tube to make the tube conform better to the upper airway anatomy of the specific individual. This aid is commonly used with a difficult laryngoscopy. Just as with laryngoscope blades, there are also several types of available stylets, such as the Verathon Stylet, which is specifically designed to follow the 60° blade angle of the GlideScope video laryngoscope.The Eschmann tracheal tube introducer (often incorrectly referred to as a "gum elastic bougie") is specialized type of stylet used to facilitate difficult intubation. This flexible device is 60 cm (23.6 in) in length, 15 French
French catheter scale
The French scale or French gauge system is commonly used to measure the size of a catheter. It is most often abbreviated as Fr, but can often abbreviated as FR or F. It may also be abbreviated as CH or Ch in French speaking countries...
(5 mm diameter) with a small "hockey-stick" angle at the far end. Unlike a traditional intubating stylet, the Eschmann tracheal tube introducer is typically inserted directly into the trachea and then used as a guide over which the endotracheal tube can be passed (in a manner analogous to the Seldinger technique
Seldinger technique
The Seldinger technique is a medical procedure to obtain safe access to blood vessels and other hollow organs. It is named after Dr. Sven-Ivar Seldinger , a Swedish radiologist from Mora, Dalarna County, who introduced the procedure in 1953....
). As the Eschmann tracheal tube introducer is considerably less rigid than a conventional stylet, this technique is considered to be a relatively atraumatic means of tracheal intubation.
The tracheal tube exchanger is a hollow catheter
Catheter
In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. Catheters thereby allow drainage, administration of fluids or gases, or access by surgical instruments. The process of inserting a catheter is catheterization...
, 56 to 81 cm (22 to 31.9 in) in length, that can be used for removal and replacement of tracheal tubes without the need for laryngoscopy. The Cook Airway Exchange Catheter (CAEC) is another example of this type of catheter; this device has a central lumen
Lumen (anatomy)
A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
(hollow channel) through which oxygen can be administered
Insufflation (medicine)
Insufflation is the practice of inhaling a substance. Insufflation has limited medical use, but is a common route of administration with many respiratory drugs used to treat conditions in the lungs and paranasal sinus .The technique is common for many recreational drugs and is also used for some...
.
The lighted stylet is a device that employs the principle of transillumination
Transillumination
Transillumination is the technique of sample illumination by transmission of light through the sample. Transillumination is used in a variety of methods of imaging.-Microscopy:...
to facilitate blind orotracheal intubation (an intubation technique in which the laryngoscopist does not view the glottis).
Tracheal tubes
Airway management
In cardiopulmonary resuscitation, anaesthesia, emergency medicine, intensive care medicine and first aid, airway management is the process of ensuring that:# there is an open pathway between a patient’s lungs and the outside world, and...
in the settings of general anesthesia, critical care, mechanical ventilation and emergency medicine. Many different types of tracheal tubes are available, suited for different specific applications. An endotracheal tube is a specific type of tracheal tube that is nearly always inserted through the mouth (orotracheal) or nose (nasotracheal). It is a breathing
Breathing
Breathing is the process that moves air in and out of the lungs. Aerobic organisms require oxygen to release energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. Breathing is only one process that delivers oxygen to where it is needed in the body and...
conduit designed to be placed into the airway of critically injured, ill or anesthetized patients in order to perform mechanical positive pressure ventilation of the lungs and to prevent the possibility of aspiration or airway obstruction. The endotracheal tube has a fitting designed to be connected to a source of pressurized gas such as oxygen. At the other end is an orifice through which such gases are directed into the lungs and may also include a balloon (referred to as a cuff). The tip of the endotracheal tube is positioned above the carina
Carina of trachea
In anatomy, the carina is a cartilaginous ridge within the trachea that runs anteroposteriorly between the two primary bronchi at the site of the tracheal bifurcation at the lower end of the trachea .The mucous membrane of the carina is the most sensitive area of the trachea and larynx...
(before the trachea divides to each lung) and sealed within the trachea so that the lungs can be ventilated equally. A tracheostomy tube is another type of tracheal tube; this 2–3 in (50.8–76.2 mm) curved metal or plastic tube is inserted into a tracheostomy stoma
Stoma (medicine)
A stoma is an opening , either natural or surgically created, which connects a portion of the body cavity to the outside environment...
or a cricothyrotomy incision.
Tracheal tubes can be used to ensure the adequate exchange
Gas exchange
Gas exchange is a process in biology where gases contained in an organism and atmosphere transfer or exchange. In human gas-exchange, gases contained in the blood of human bodies exchange with gases contained in the atmosphere. Human gas-exchange occurs in the lungs...
of oxygen and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, to deliver oxygen in higher concentrations than found in air, or to administer other gases such as helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
, nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
, nitrous oxide, xenon
Xenon
Xenon is a chemical element with the symbol Xe and atomic number 54. The element name is pronounced or . A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts...
, or certain volatile anesthetic agents such as desflurane
Desflurane
Desflurane is a highly fluorinated methyl ethyl ether used for maintenance of general anesthesia. Like halothane, enflurane and isoflurane, it is a racemic mixture of and optical isomers...
, isoflurane
Isoflurane
Isoflurane is a halogenated ether used for inhalational anesthesia. Together with enflurane and halothane, it replaced the flammable ethers used in the pioneer days of surgery. Its name comes from being a structural isomer of enflurane, hence they have the same empirical formula...
, or sevoflurane
Sevoflurane
Sevoflurane , also called fluoromethyl hexafluoroisopropyl ether, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used for induction and maintenance of general anesthesia. Together with desflurane, it is replacing isoflurane and halothane in modern anesthesiology...
. They may also be used as a route for administration of certain medications such as bronchodilator
Bronchodilator
A bronchodilator is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. Bronchodilators may be endogenous , or they may be medications administered for the treatment of breathing difficulties...
s, inhaled corticosteroids, and drugs used in treating cardiac arrest
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
such as atropine
Atropine
Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
, epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
, lidocaine
Lidocaine
Lidocaine , Xylocaine, or lignocaine is a common local anesthetic and antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning and pain from skin inflammations, injected as a dental anesthetic or as a local anesthetic for minor surgery.- History :Lidocaine, the first amino...
and vasopressin
Vasopressin
Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...
.
Originally made from latex rubber, most modern endotracheal tubes today are constructed of polyvinyl chloride
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
. Tubes constructed of silicone rubber
Silicone rubber
Silicone rubber is an elastomer composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubbers are widely used in industry, and there are multiple formulations...
, wire-reinforced silicone rubber or stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
are also available for special applications. For human use, tubes range in size from 2 to 10.5 mm (0.078740157480315 to 0.413385826771654 in) in internal diameter. The size is chosen based on the patient's body size, with the smaller sizes being used for infants and children. Most endotracheal tubes have an inflatable cuff to seal the tracheobronchial tree against leakage of respiratory gases and pulmonary aspiration of gastric contents, blood, secretions and other fluids. Uncuffed tubes are also available, though their use is limited mostly to children (in small children, the cricoid cartilage is the narrowest portion of the airway and usually provides an adequate seal for mechanical ventilation).
In addition to cuffed or uncuffed, preformed endotracheal tubes are also available. The oral and nasal RAE tubes (named after the inventors Ring, Adair and Elwyn) are the most widely used of the preformed tubes.
Various types of endotracheal tubes are available that have endobronchial as well as endotracheal channels (Carlens, White and Robertshaw tubes). These tubes are typically coaxial
Coaxial
In geometry, coaxial means that two or more forms share a common axis; it is the three-dimensional linear analogue of concentric.Coaxial cable, as a common example, has a wire conductor in the centre a circumferential outer conductor and an insulating medium called the dielectric separating...
, with two separate channels and two separate openings. They incorporate an endotracheal lumen which terminates in the trachea and an endobronchial lumen, the distal tip of which is positioned 1–2 cm into the right or left mainstem bronchus. There is also the Univent tube, which has a single tracheal lumen and an integrated endobronchial blocker. These tubes enable one to ventilate both lungs, or either lung independently. Single-lung ventilation (allowing the lung on the operative side to collapse) can be useful during thoracic surgery
Thoracic surgery
Thoracic surgery is the field of medicine involved in the surgical treatment of diseases affecting organs inside the thorax . Generally treatment of conditions of the lungs, chest wall, and diaphragm....
, as it can facilitate the surgeon's view and access to other relevant structures within the thoracic cavity
Thoracic cavity
The thoracic cavity is the chamber of the human body that is protected by the thoracic wall ....
.
The "armored" endotracheal tubes are cuffed, wire-reinforced silicone rubber tubes. They are much more flexible than polyvinyl chloride tubes, yet they are difficult to compress or kink. This can make them useful for situations in which the trachea is anticipated to remain intubated for a prolonged duration, or if the neck is to remain flexed during surgery. Most armored tubes have a Magill curve, but preformed armored RAE tubes are also available. Another type of endotracheal tube has four small openings just above the inflatable cuff, which can be used for suction of the trachea or administration of intratracheal medications if necessary. Other tubes (such as the Bivona Fome-Cuf tube) are designed specifically for use in laser surgery in and around the airway.
Methods to confirm tube placement
No single method for confirming tracheal tube placement has been shown to be 100% reliable. Accordingly, the use of multiple methods for confirmation of correct tube placement is now widely considered to be the standard of care. Such methods include direct visualization as the tip of the tube passes through the glottis or visualization with a bronchoschope of the ETT within trachea. With a properly positioned tracheal tube, equal bilateral breath sounds will be heard upon listening toAuscultation
Auscultation is the term for listening to the internal sounds of the body, usually using a stethoscope...
the chest with a stethoscope, and no sound upon listening to the area over the stomach
Epigastrium
The epigastrium is the upper central region of the abdomen. It is located between the costal margins and the subcostal plane....
. Equal bilateral rise and fall of the chest wall will be evident with ventilatory excursions. A small amount of water vapor
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...
will also be evident within the lumen of the tube with each exhalation and there will be no gastric contents in the tracheal tube at any time.
Ideally, at least one of the methods utilized for confirming tracheal tube placement will be a measuring instrument
Measuring instrument
In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item...
. Waveform capnography
Capnography
Capnography is the monitoring of the concentration or partial pressure of carbon dioxide in the respiratory gases. Its main development has been as a monitoring tool for use during anaesthesia and intensive care. It is usually presented as a graph of expiratory plotted against time, or, less...
has emerged as the gold standard
Gold standard (test)
In medicine and statistics, gold standard test refers to a diagnostic test or benchmark that is the best available under reasonable conditions. It does not have to be necessarily the best possible test for the condition in absolute terms...
for the confirmation of tube placement within the trachea. Other methods relying on instruments include the use of a colorimetric
Colorimetry
Colorimetry is "the science and technology used to quantify and describe physically the human color perception."It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color perception, most often the CIE 1931 XYZ color space...
end-tidal carbon dioxide detector, a self-inflating esophageal bulb, or an esophageal detection device. The distal tip of a properly positioned tracheal tube will be located in the mid-trachea, roughly 2 cm (0.78740157480315 in) above the bifurcation of the carina; this can be confirmed by chest x-ray. If the tracheal tube is inserted too far into the trachea, the tip will more likely be within the right main bronchus
Bronchus
A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles....
, because this bronchus has a less acute angle than the left.
Emergencies
Tracheal intubation in the emergency setting can be difficult with the fiberoptic bronchoscope due to blood, vomit, or secretionSecretion
Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland. In contrast to excretion, the substance may have a certain function, rather than being a waste product...
s in the airway and poor patient cooperation. Because of this, patients with massive facial injury, complete upper airway obstruction, severe hypoventilation, or profuse upper airway bleeding are poor candidates for fiberoptic intubation. Fiberoptic intubation under general anesthesia typically requires two skilled individuals. Success rates of only 83–87% have been reported using fiberoptic techniques in the emergency department, with significant nasal bleeding occurring in up to 22% of patients. These drawbacks limit the use of fiberoptic bronchoscopy somewhat in urgent and emergent situations.
Personnel experienced in direct laryngoscopy are not always immediately available in certain settings that require emergency tracheal intubation. For this reason, specialized devices have been designed to act as bridges to a definitive airway. Such devices include the laryngeal mask airway, cuffed oropharyngeal
Human pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
airway and the esophageal-tracheal combitube (Combitube
Combitube
The Combitube is a blind insertion airway device often used in the pre-hospital, emergency setting. It is designed to facilitate the tracheal intubation of a patient in respiratory distress. It consists of a cuffed, double-lumen tube that is inserted into a the patient's airway facilitating...
). Other devices such as rigid stylets, the lightwand (a blind technique) and indirect fiberoptic rigid stylets, such as the Bullard scope, Upsher scope and the WuScope can also be used as alternatives to direct laryngoscopy. Each of these devices have its own unique set of benefits and drawbacks, and none of them is effective under all circumstances.
Rapid-sequence induction and intubation
Rapid sequence inductionRapid sequence induction
Rapid Sequence Induction is a medical procedure involving the expeditious induction of general anesthesia and subsequent intubation of the trachea. RSI is generally used in an emergency setting or for patients who have an increased risk of aspirating stomach contents into the lungs...
and intubation (RSI) is a particular method of induction of general anesthesia, commonly employed in emergency operations and other situations where patients are assumed to have a "full stomach". The objective of RSI is to minimize the possibility of regurgitation
Regurgitation (digestion)
Regurgitation is the expulsion of material from the mouth, pharynx, or esophagus, usually characterized by the presence of undigested food or blood.Regurgitation is used by a number of species to feed their young...
and pulmonary aspiration of gastric contents during the induction of general anesthesia and subsequent tracheal intubation. RSI traditionally involves preoxygenating the lungs with a tightly-fitting oxygen mask, followed by the sequential administration of an intravenous sleep-inducing
Hypnotic
Hypnotic drugs are a class of psychoactives whose primary function is to induce sleep and to be used in the treatment of insomnia and in surgical anesthesia...
agent and a rapidly-acting neuromuscular-blocking drug, before intubation of the trachea.
One important difference between RSI and routine tracheal intubation is that the practitioner does not manually assist the ventilation of the lungs after the onset of general anesthesia and cessation of breathing
Apnea
Apnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
, until the trachea has been intubated and the cuff has been inflated. Another key feature of RSI is the application of manual pressure to the cricoid cartilage, often referred to as the "Sellick maneuver", prior to instrumentation of the airway and intubation of the trachea.
Since the introduction of RSI, there has been controversy regarding virtually every aspect of this technique, including:
- choice of induction drug, dose and method of administration.
- avoidance of manual ventilation before tracheal intubation.
- optimal position and whether the head-up, head-down, or horizontal supine position is the safest for induction of anesthesia in full-stomach patients.
- application of cricoid pressure (the Sellick maneuver).
Named for British anesthetist Brian Arthur Sellick (1918–1996) who first described the procedure in 1961, the goal of the Sellick maneuver is to minimize the possibility of regurgitation and pulmonary aspiration of gastric contents. Cricoid pressure has been widely used during RSI for nearly fifty years, despite a lack of compelling evidence to support this practice. The initial article by Sellick was based on a small sample size at a time when high tidal volume
Tidal volume
Tidal volume is the lung volume representing the normal volume of air displaced between normal inspiration and expiration when extra effort is not applied.Typical values are around 500ml or 7ml/kg bodyweight.-Mechanical Ventilation:...
s, head-down positioning
Trendelenburg position
In the Trendelenburg position the body is laid flat on the back with the feet higher than the head by 15-30 degrees, in contrast to the reverse Trendelenburg position, where the body is tilted in the opposite direction. This is a standard position used in abdominal and gynecological surgery...
and barbiturate
Barbiturate
Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...
anesthesia were the rule. Beginning around 2000, a significant body of evidence has accumulated which questions the effectiveness of the Sellick maneuver. The application of cricoid pressure may in fact displace the esophagus laterally instead of compressing it as described by Sellick. Cricoid pressure may also compress the glottis, which can obstruct the view of the laryngoscopist and actually cause a delay in securing the airway.
The Sellick maneuver is often confused with the "BURP" (Backwards Upwards Rightwards Pressure) maneuver. While both of these involve digital pressure to the anterior aspect (front) of the laryngeal apparatus, the purpose of the latter is to improve the view of the glottis during laryngoscopy and tracheal intubation, rather than to prevent regurgitation.
Cricothyrotomy
Cricothyroid ligament
The cricothyroid ligament is the larger part of the laryngeal membrane, continuing inferiorly as a median or anterior part and twin lateral ligaments....
to establish a patent airway during certain life-threatening situations, such as airway obstruction by a foreign body, angioedema, or massive facial trauma. A cricothyrotomy is nearly always performed as a last resort in cases where orotracheal and nasotracheal intubation are impossible or contraindicated. Cricothyrotomy is easier and quicker to perform than tracheotomy, does not require manipulation of the cervical spine and is associated with fewer complications.
The quickest and easiest method to perform this technique is the needle cricothyrotomy (also referred to as a percutaneous
Percutaneous
In surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...
dilational cricothyrotomy), in which a large-bore (12–14 gauge
Needle gauge comparison chart
Hypodermic needles are available in a wide variety of outer diameters described by gauge numbers. Smaller gauge numbers indicate larger outer diameters. Inner diameter depends on both gauge and wall thickness. The following chart shows nominal inner diameter and wall thickness for regular-wall...
) intravenous catheter
Peripheral venous catheter
In medicine, a peripheral venous catheter is a catheter placed into a peripheral vein in order to administer medication or fluids...
is used to puncture the cricothyroid membrane. Oxygen can then be administered through this catheter via jet insufflation. However, while needle cricothyrotomy may be life-saving in extreme circumstances, this technique is only intended to be a temporizing measure until a definitive airway can be established. While needle cricothyrotomy can provide adequate oxygenation, the small diameter of the cricothyrotomy catheter is insufficient for elimination of carbon dioxide (ventilation). After one hour of apneic oxygenation through a needle cricothyrotomy, one can expect a PaCO2
Arterial blood gas
An arterial blood gas is a blood test that is performed using blood from an artery. It involves puncturing an artery with a thin needle and syringe and drawing a small volume of blood. The most common puncture site is the radial artery at the wrist, but sometimes the femoral artery in the groin or...
of greater than 250 mm Hg and an arterial pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
of less than 6.72, despite an oxygen saturation of 98% or greater. A more definitive airway can be established by performing a surgical cricothyrotomy, in which a 5 to 6 mm (0.196850393700787 to 0.236220472440945 in) endotracheal tube or tracheostomy tube can be inserted through a larger incision.
Several manufacturers market prepackaged cricothyrotomy kits, which enable one to use either a wire-guided percutaneous dilational (Seldinger) technique, or the classic surgical technique to insert a polyvinylchloride catheter through the cricothyroid membrane. The kits may be stocked in hospital emergency departments and operating suites, as well as ambulances and other selected pre-hospital
Emergency medical services
Emergency medical services are a type of emergency service dedicated to providing out-of-hospital acute medical care and/or transport to definitive care, to patients with illnesses and injuries which the patient, or the medical practitioner, believes constitutes a medical emergency...
settings.
Tracheotomy
Stoma (medicine)
A stoma is an opening , either natural or surgically created, which connects a portion of the body cavity to the outside environment...
can serve independently as an airway or as a site for a tracheostomy tube to be inserted; this tube allows a person to breathe without the use of their nose or mouth. The opening may be made by a scalpel or a needle (referred to as surgical and percutaneous techniques respectively) and both techniques are widely used in current practice. In order to limit the risk of damage to the recurrent laryngeal nerve
Recurrent laryngeal nerve
The recurrent laryngeal nerve is a branch of the vagus nerve that supplies motor function and sensation to the larynx . It travels within the endoneurium...
s (the nerves that control the voicebox
Vocal folds
The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of mucous membrane stretched horizontally across the larynx...
), the tracheotomy is performed as high in the trachea as possible. If only one of these nerves is damaged, the patient's voice may be impaired (dysphonia
Dysphonia
Dysphonia is the medical term for disorders of the voice: an impairment in the ability to produce voice sounds using the vocal organs . Thus, dysphonia is a phonation disorder...
); if both of the nerves are damaged, the patient will be unable to speak (aphonia
Aphonia
Aphonia is the inability to speak. It is considered more severe than dysphonia. A primary cause of aphonia is bilateral disruption of the recurrent laryngeal nerve, which supplies nearly all the muscles in the larynx...
). In the acute setting, indications for tracheotomy are similar to those for cricothyrotomy. In the chronic setting, indications for tracheotomy include the need for long-term mechanical ventilation and removal of tracheal secretions (e.g., comatose patients, or extensive surgery involving the head and neck).
Children
There are significant differences in airway anatomy and respiratory physiology between children and adults, and these are taken into careful consideration before performing tracheal intubation of any pediatricPediatrics
Pediatrics or paediatrics is the branch of medicine that deals with the medical care of infants, children, and adolescents. A medical practitioner who specializes in this area is known as a pediatrician or paediatrician...
patient. The differences, which are quite significant in infants, gradually disappear as the human body approaches a mature age and body mass index
Body mass index
The body mass index , or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing...
.
For infants and young children, orotracheal intubation is easier than the nasotracheal route. Nasotracheal intubation carries a risk of dislodgement of adenoids and nasal bleeding. Despite the greater difficulty, nasotracheal intubation route is preferable to orotracheal intubation in children undergoing intensive care and requiring prolonged intubation because this route allows a more secure fixation of the tube. As with adults, there are a number of devices specially designed for assistance with difficult tracheal intubation in children. Confirmation of proper position of the tracheal tube is accomplished as with adult patients.
Because the airway of a child is narrow, a small amount of glottic or tracheal swelling
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
can produce critical obstruction. Inserting a tube that is too large relative to the diameter of the trachea can cause swelling. Conversely, inserting a tube that is too small can result in inability to achieve effective positive pressure ventilation due to retrograde escape of gas through the glottis and out the mouth and nose (often referred to as a "leak" around the tube). An excessive leak can usually be corrected by inserting a larger tube or a cuffed tube.
The tip of a correctly positioned tracheal tube will be in the mid-trachea, between the collarbones
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...
on an anteroposterior chest radiograph. The correct diameter of the tube is that which results in a small leak at a pressure of about 25 cm (9.8 in) of water. The appropriate inner diameter for the endotracheal tube is estimated to be roughly the same diameter as the child's little finger. The appropriate length for the endotracheal tube can be estimated by doubling the distance from the corner of the child's mouth to the ear canal
Ear canal
The ear canal , is a tube running from the outer ear to the middle ear. The human ear canal extends from the pinna to the eardrum and is about 35 mm in length and 5 to 10 mm in diameter....
. For premature infants 2.5 mm (0.0984251968503937 in) internal diameter is an appropriate size for the tracheal tube. For infants of normal gestational age
Gestational age
Gestational age relates to the age of an embryo or fetus . There is some ambiguity in how it is defined:*In embryology, gestational age is the time elapsed since conception. This interval is also termed fertilisation age....
, 3 mm (0.118110236220472 in) internal diameter is an appropriate size. For normally nourished children 1 year of age and older, the following formulae estimate the proper diameter and depth of insertion for tracheal tubes:
- Internal diameter of tube (mm) = (patient's age in years + 16) / 4
- Appropriate depth of insertion of orotracheal tube (cm) = 12 + (patient's age in years / 2)
Predicting difficulty
Tracheal intubation is not a simple procedure and the consequences of failure are grave. Therefore the patient is carefully evaluated for potential difficulty or complications beforehand. This involves taking the medical historyMedical history
The medical history or anamnesis of a patient is information gained by a physician by asking specific questions, either of the patient or of other people who know the person and can give suitable information , with the aim of obtaining information useful in formulating a diagnosis and providing...
of the patient and performing a physical examination
Physical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
, the results of which can be scored against one of several classification systems. The proposed surgical procedure (e.g., surgery involving the head and neck, or bariatric surgery
Bariatric surgery
Bariatric surgery includes a variety of procedures performed on people who are obese. Weight loss is achieved by reducing the size of the stomach with an implanted medical device or through removal of a portion of the stomach or by resecting and re-routing the small intestines...
) may lead one to anticipate difficulties with intubation. Many individuals have unusual airway anatomy, such as those who have limited movement of their neck or jaw, or those who have tumors, deep swelling due to injury
Hematoma
A hematoma, or haematoma, is a localized collection of blood outside the blood vessels, usually in liquid form within the tissue. This distinguishes it from an ecchymosis, which is the spread of blood under the skin in a thin layer, commonly called a bruise...
or to allergy
Angioedema
Angioedema or Quincke's edema is the rapid swelling of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis...
, developmental abnormalities of the jaw, or excess fatty tissue of the face and neck. Using conventional laryngoscopic techniques, intubation of the trachea can be difficult or even impossible in such patients. This is why all persons performing tracheal intubation must be familiar with alternative techniques of securing the airway. Use of the flexible fiberoptic bronchoscope and similar devices has become among the preferred techniques in the management of such cases. However, these devices require a different skill set than that employed for conventional laryngoscopy and are expensive to purchase, maintain and repair.
When taking the patient's medical history, the subject is questioned about any significant signs
Medical sign
A medical sign is an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination of a patient....
or symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s, such as difficulty in speaking
Dysphonia
Dysphonia is the medical term for disorders of the voice: an impairment in the ability to produce voice sounds using the vocal organs . Thus, dysphonia is a phonation disorder...
or difficulty in breathing
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
. These may suggest obstructing lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
s in various locations within the upper airway, larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
, or tracheobronchial tree. A history of previous surgery (e.g., previous cervical fusion
Anterior cervical discectomy and fusion
Anterior cervical discectomy and fusion is a surgical procedure to treat nerve root or spinal cord compression by decompressing the spinal cord and nerve roots of the cervical spine in order to stabilize the corresponding vertebrae...
), injury, radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
, or tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
s involving the head, neck and upper chest
Mediastinum
The mediastinum is a non-delineated group of structures in the thorax, surrounded by loose connective tissue. It is the central compartment of the thoracic cavity...
can also provide clues to a potentially difficult intubation. Previous experiences with tracheal intubation, especially difficult intubation, intubation for prolonged duration (e.g., intensive care unit) or prior tracheotomy are also noted.
A detailed physical examination
Physical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
of the airway is important, particularly:
- the range of motion of the cervical spineCervical vertebraeIn vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...
: the subject should be able to tilt the head back and then forward so that the chin touches the chest. - the range of motion of the jaw (the temporomandibular jointTemporomandibular jointThe temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. There are two TMJs, one on either side, working in unison. The name is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium , and the lower jaw bone called the...
): three of the subject's fingers should be able to fit between the upper and lower incisors. - the size and shape of the upper jawMaxillaThe maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
and lower jaw, looking especially for problems such as maxillary hypoplasiaMaxillary hypoplasiaMaxillary hypoplasia is the name that dentists have given to the underdevelopment of the maxillary bones, which produces midfacial retrusion and creates the illusion of protuberance of the lower jaw. It is associated with Crouzon syndrome....
(an underdeveloped upper jaw), micrognathiaMicrognathismMicrognathism is a condition where the jaw is undersized. It is also sometimes called "Mandibular hypoplasia". It is common in infants, but is usually self-corrected during growth, due to the jaws increasing in size. It may be a cause of abnormal tooth alignment and in severe cases can hamper...
(an abnormally small jaw), or retrognathiaRetrognathismRetrognathia is a type of malocclusion which refers to an abnormal posterior positioning of the maxilla or mandible, particularly the mandible, relative to the facial skeleton and soft tissues....
(misalignment of the upper and lower jaw). - the thyromental distance: three of the subject's fingers should be able to fit between the Adam's appleThyroid cartilageThe thyroid cartilage is the largest of the nine cartilages that make up the laryngeal skeleton, the cartilage structure in and around the trachea that contains the larynx....
and the chin. - the size and shape of the tongue and palatePalateThe palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
relative to the size of the mouth. - the teeth, especially noting the presence of prominent maxillary incisors, any loose or damaged teeth, or crownsCrown (dentistry)A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed when a large cavity threatens the ongoing health of a tooth. They are typically bonded to the tooth using a dental cement. Crowns can be made from many materials, which...
.
Many classification systems have been developed in an effort to predict difficulty of tracheal intubation, including the Cormack-Lehane grading system, the Intubation Difficulty Scale (IDS), and the Mallampati score
Mallampati score
In anesthesia, the Mallampati score, also Mallampati classification, is used to predict the ease of intubation. It is determined by looking at the anatomy of the oral cavity; specifically, it is based on the visibility of the base of uvula, faucial pillars and soft palate. Scoring may be done...
. The Mallampati score is drawn from the observation that the size of the base of the tongue
Posterior tongue
The Posterior tongue, or pharyngeal part, is the part of the tongue behind the terminal sulcus.At its root, it is directed backward, and connected with the hyoid bone by the Hyoglossi and Genioglossi muscles and the hyoglossal membrane; with the epiglottis by three folds of mucous membrane; with...
influences the difficulty of intubation. It is determined by looking at the anatomy of the mouth, and in particular the visibility of the base of palatine uvula, faucial pillars and the soft palate
Soft palate
The soft palate is the soft tissue constituting the back of the roof of the mouth. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone....
. Although such medical scoring systems may aid in the evaluation of patients, no single score or combination of scores can be trusted to specifically detect all and only those patients who are difficult to intubate. Furthermore, one study of experienced anesthesiologists, on the widely used Cormack–Lehane classification system, found they did not score the same patients consistently over time, and that only 25% could correctly define all four grades of the widely used Cormack–Lehane classification system. Under certain emergency circumstances (e.g., severe head trauma or suspected cervical spine injury), it may be impossible to fully utilize these the physical examination and the various classification systems to predict the difficulty of tracheal intubation. In such cases, alternative techniques of securing the airway must be readily available.
Complications
Tracheal intubation is generally considered the best method for airway management under a wide variety of circumstances, as it provides the most reliable means of oxygenation and ventilation and the greatest degree of protection against regurgitation and pulmonary aspiration. However, tracheal intubation requires a great deal of clinical experience to master and serious complications may result even when properly performed.Four anatomic features must be present for orotracheal intubation to be straightforward: adequate mouth opening (full range of motion of the temporomandibular joint), sufficient pharyngeal space (determined by examining the hypopharynx), sufficient submandibular space (distance between the thyroid cartilage and the chin, the space into which the tongue must be displaced in order for the larygoscopist to view the glottis), and adequate extension of the cervical spine at the atlanto-occipital joint. If any of these variables is in any way compromised, intubation should be expected to be difficult.
Minor complications are common after laryngoscopy and insertion of an orotracheal tube. These are typically of short duration, such as sore throat, lacerations of the lips or gums
Gingiva
The gingiva , or gums, consists of the mucosal tissue that lies over the mandible and maxilla inside the mouth.-General description:...
or other structures within the upper airway, chipped, fractured or dislodged teeth, nasal injury, Other complications which are common but potentially more serious include accelerated
Tachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
or irregular
Cardiac dysrhythmia
Cardiac dysrhythmia is any of a large and heterogeneous group of conditions in which there is abnormal electrical activity in the heart. The heart beat may be too fast or too slow, and may be regular or irregular.Some arrhythmias are life-threatening medical emergencies that can result in cardiac...
heartbeat, high blood pressure
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
, elevated intracranial
Intracranial pressure
Intracranial pressure is the pressure inside the skull and thus in the brain tissue and cerebrospinal fluid . The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF...
and introcular
Intraocular pressure
Intraocular pressure is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk from glaucoma...
pressure, and bronchospasm
Bronchospasm
Bronchospasm or a bronchial spasm is a sudden constriction of the muscles in the walls of the bronchioles. It is caused by the release of substances from mast cells or basophils under the influence of anaphylatoxins...
.
More serious complications include laryngospasm
Laryngospasm
In medicine, laryngospasm is an uncontrolled/involuntary muscular contraction of the laryngeal cords. The condition typically lasts less than 60 seconds, and causes a partial blocking of breathing in, while breathing out remains easier. It may be triggered when the vocal cords or the area of the...
, perforation of the trachea
Tracheobronchial injury
Tracheobronchial injury is damage to the tracheobronchial tree . It can result from blunt or penetrating trauma to the neck or chest, inhalation of harmful fumes or smoke, or aspiration of liquids or objects.Though rare, TBI is a serious condition; it may cause obstruction of the airway with...
or esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
, pulmonary aspiration of gastric contents or other foreign bodies, fracture or dislocation of the cervical spine, temporomandibular joint
Temporomandibular joint
The temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. There are two TMJs, one on either side, working in unison. The name is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium , and the lower jaw bone called the...
or arytenoid cartilage
Arytenoid cartilage
The arytenoid cartilages are a pair of small three-sided pyramids which form part of the larynx, to which the vocal folds are attached...
s, decreased oxygen content, elevated arterial carbon dioxide
Hypercapnia
Hypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...
, and vocal cord weakness
Vocal cord paresis
Vocal cord paresis is weakness of one or both vocal folds. Symptoms of paresis include hoarseness; vocal fatigue; mild to severe reduction in vocal volume; pain in the throat when speaking; shortness of breath; aspiration with frequent resultant coughing, and in extreme cases may cause death...
. In addition to these complications, tracheal intubation via the nasal route carries a risk of dislodgement of adenoids and potentially severe nasal bleeding. Newer technologies such as flexible fiberoptic laryngoscopy have fared better in reducing the incidence of some of these complications, though the most frequent cause of intubation trauma remains a lack of skill on the part of the laryngoscopist.
Complications may also be severe and long-lasting or permanent, such as vocal cord damage, esophageal perforation and retropharyngeal abscess
Retropharyngeal abscess
Most commonly seen in infants and young children, retropharyngeal abscess is an abscess located in the tissues in the back of the throat behind the posterior pharyngeal wall . Because RPA's typically occur in deep tissue, they are difficult to diagnose by physical examination alone...
, bronchial intubation, or nerve injury. They may even be immediately life-threatening, such as laryngospasm and negative pressure pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
(fluid in the lungs), aspiration, unrecognized esophageal intubation, or accidental disconnection or dislodgement of the tracheal tube. Potentially fatal complications more often associated with prolonged intubation and/or tracheotomy include abnormal communication between the trachea and nearby structures such as the innominate artery
Brachiocephalic artery
The brachiocephalic artery is an artery of the mediastinum that supplies blood to the right arm and the head and neck....
(tracheoinnominate fistula
Fistula
In medicine, a fistula is an abnormal connection or passageway between two epithelium-lined organs or vessels that normally do not connect. It is generally a disease condition, but a fistula may be surgically created for therapeutic reasons.-Locations:Fistulas can develop in various parts of the...
) or esophagus (tracheoesophageal fistula
Tracheoesophageal fistula
A tracheoesophageal fistula is an abnormal connection between the esophagus and the trachea...
). Other significant complications include airway obstruction due to loss of tracheal rigidity
Tracheomalacia
Tracheomalacia is a condition characterized by flaccidity of the tracheal support cartilage which leads to tracheal collapse especially when increased airflow is demanded....
, ventilator-associated pneumonia
Ventilator-associated pneumonia
Ventilator-associated pneumonia is a sub-type of hospital-acquired pneumonia which occurs in people who are receiving mechanical ventilation. VAP is not characterized by the causative agents; rather, as its name implies, definition of VAP is restricted to patients undergoing mechanical...
and narrowing
Subglottic stenosis
Subglottic stenosis is a congenital or acquired narrowing of the subglottic airway. Although it is relatively rare, it is the third most common congenital airway problem . Subglottic stenosis can present as a life-threatening airway emergency...
of the glottis or trachea. The cuff pressure is monitored carefully in order to avoid complications from over-inflation, many of which can be traced to excessive cuff pressure restricting the blood supply to
Ischemia
In medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
the tracheal mucosa. A 2000 Spanish study of bedside percutaneous tracheotomy reported overall complication rates of 10–15% and procedural mortality of 0%, which is comparable to those of other series reported in the literature from the Netherlands and the United States.
Inability to secure the airway, with subsequent failure of oxygenation and ventilation is a life-threatening complication which if not immediately corrected leads to hypoxia, brain damage, cardiovascular collapse
Circulatory collapse
A circulatory collapse is defined as a general or specific failure of the circulation, either cardiac or peripheral in nature. A common cause of this could be shock or trauma from injury or surgery...
, and death. When performed improperly, the associated complications (e.g., unrecognized esophageal intubation) may be rapidly fatal. Without adequate training and experience, the incidence of such complications is unacceptably high. For example, among paramedic
Paramedic
A paramedic is a healthcare professional that works in emergency medical situations. Paramedics provide advanced levels of care for medical emergencies and trauma. The majority of paramedics are based in the field in ambulances, emergency response vehicles, or in specialist mobile units such as...
s in several United States urban communities, unrecognized esophageal or hypopharyngeal
Human pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
intubation has been reported to be 6% to 25%. Among providers at the basic emergency medical technician
Emergency medical technician
Emergency Medical Technician or Ambulance Technician are terms used in some countries to denote a healthcare provider of emergency medical services...
(EMT-B) level, reported success rates for tracheal intubation are as low as 51%. In one study, nearly half of patients with misplaced tracheal tubes died in the emergency room. Because of this, recent editions of the American Heart Association
American Heart Association
The American Heart Association is a non-profit organization in the United States that fosters appropriate cardiac care in an effort to reduce disability and deaths caused by cardiovascular disease and stroke. It is headquartered in Dallas, Texas...
's Guidelines for Cardiopulmonary Resuscitation have de-emphasized the role of tracheal intubation in favor of other airway management techniques such as bag-valve-mask ventilation, the laryngeal mask airway and the Combitube.
One complication—unintentional and unrecognized intubation of the esophagus—is both common (as frequent as 25% in the hands of inexperienced personnel) and likely to result in a deleterious or even fatal outcome. In such cases, oxygen is inadvertently administered to the stomach, from where it cannot be taken up by the circulatory system
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
, instead of the lungs. If this situation is not immediately identified and corrected, death will ensue from cerebral and cardiac anoxia.
Of 4,460 claims in the American Society of Anesthesiologists
American Society of Anesthesiologists
The American Society of Anesthesiologists is an association of physicians, primarily anesthesiologists, that share a common goal of raising the standard of the medical specialty of anesthesiology and the improvement of patient care by fostering and encouraging education through research and...
(ASA) Closed Claims Project database, 266 (approximately 6%) were for airway injury. Of these 266 cases, 87% of the injuries were temporary, 5% were permanent or disabling, and 8% resulted in death. Difficult intubation, age older than 60 years, and female gender were associated with claims for perforation of the esophagus or pharynx. Early signs of perforation were present in only 51% of perforation claims, whereas late sequelae occurred in 65%.
Alternatives
Although it offers the greatest degree of protection against regurgitation and pulmonary aspiration, tracheal intubation is not the only means to maintain a patent airway. Alternative techniques for airway management and delivery of oxygen, volatile anesthetics or other breathing gasBreathing gas
Breathing gas is a mixture of gaseous chemical elements and compounds used for respiration.Air is the most common and only natural breathing gas...
es include the laryngeal mask airway, i-gel, cuffed oropharyngeal airway, continuous positive airway pressure (CPAP mask), nasal BiPAP mask, simple face mask, and nasal cannula.
General anesthesia is often administered without tracheal intubation in selected cases where the procedure is brief in duration, or procedures where the depth of anesthesia is not sufficient to cause significant compromise in ventilatory function. Even for longer duration or more invasive procedures, a general anesthetic may be administered without intubating the trachea, provided that patients are carefully selected, and the risk-benefit ratio
Risk-benefit analysis
Risk–benefit analysis is the comparison of the risk of a situation to its related benefits. Exposure to personal risk is recognized as a normal aspect of everyday life. We accept a certain level of risk in our lives as necessary to achieve certain benefits. In most of these risks we feel as though...
is favorable (i.e., the risks associated with an unprotected airway are believed to be less than the risks of intubating the trachea).
History
TracheotomyThe earliest known depiction of a tracheotomy is found on two Egyptian tablets dating back to around 3600 BC. The 110-page Ebers Papyrus
Ebers papyrus
The Ebers Papyrus, also known as Papyrus Ebers, is an Egyptian medical papyrus dating to circa 1550 BC. Among the oldest and most important medical papyri of ancient Egypt, it was purchased at Luxor, in the winter of 1873–74 by Georg Ebers...
, an Egyptian medical papyrus which dates to roughly 1550 BC, also makes reference to the tracheotomy. Tracheotomy was described in the Rigveda
Rigveda
The Rigveda is an ancient Indian sacred collection of Vedic Sanskrit hymns...
, a Sanskrit
Sanskrit
Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...
text of ayurvedic medicine
Ayurveda
Ayurveda or ayurvedic medicine is a system of traditional medicine native to India and a form of alternative medicine. In Sanskrit, words , meaning "longevity", and , meaning "knowledge" or "science". The earliest literature on Indian medical practice appeared during the Vedic period in India,...
written around 2000 BC in ancient India
Indus Valley Civilization
The Indus Valley Civilization was a Bronze Age civilization that was located in the northwestern region of the Indian subcontinent, consisting of what is now mainly modern-day Pakistan and northwest India...
. The Sushruta Samhita
Sushruta Samhita
The Sushruta Samhita is a Sanskrit text, attributed to one Sushruta, foundational to Ayurvedic medicine , with innovative chapters on surgery....
from around 400 BC is another text from the Indian subcontinent on ayurvedic medicine and surgery that mentions tracheotomy. Asclepiades of Bithynia
Asclepiades of Bithynia
Asclepiades was a Greek physician born at Prusa in Bithynia in Asia Minor and flourished at Rome, where he established Greek medicine near the end of the 2nd century BCE. He attempted to build a new theory of disease, based on the flow of atoms through pores in the body...
(c. 124–40 BC) is often credited as being the first physician to perform a non-emergency tracheotomy. Galen
Galen
Aelius Galenus or Claudius Galenus , better known as Galen of Pergamon , was a prominent Roman physician, surgeon and philosopher...
of Pergamon
Pergamon
Pergamon , or Pergamum, was an ancient Greek city in modern-day Turkey, in Mysia, today located from the Aegean Sea on a promontory on the north side of the river Caicus , that became the capital of the Kingdom of Pergamon during the Hellenistic period, under the Attalid dynasty, 281–133 BC...
(AD 129–199) clarified the anatomy of the trachea and was the first to demonstrate that the larynx generates the voice. In one of his experiments, Galen used bellows to inflate the lungs of a dead animal. Ibn Sīnā
Avicenna
Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā , commonly known as Ibn Sīnā or by his Latinized name Avicenna, was a Persian polymath, who wrote almost 450 treatises on a wide range of subjects, of which around 240 have survived...
(980–1037) described the use of tracheal intubation to facilitate breathing in 1025 in his 14-volume medical encyclopedia, The Canon of Medicine
The Canon of Medicine
The Canon of Medicine is an encyclopedia of Galenic medicine in five books compiled by Ibn Sīnā and completed in 1025. It presents a clear and organized summary of all the medical knowledge of the time...
. In the 12th century medical textbook Al-Taisir, Ibn Zuhr
Ibn Zuhr
Abū Merwān ’Abdal-Malik ibn Zuhr was a Muslim physician, surgeon and teacher in Al-Andalus.He was born at Seville...
(1092–1162)—also known as Avenzoar—of Al-Andalus
Andalusia
Andalusia is the most populous and the second largest in area of the autonomous communities of Spain. The Andalusian autonomous community is officially recognised as a nationality of Spain. The territory is divided into eight provinces: Huelva, Seville, Cádiz, Córdoba, Málaga, Jaén, Granada and...
provided a correct description of the tracheotomy operation.
The first detailed descriptions of tracheal intubation and subsequent artificial respiration
Artificial respiration
Artificial respiration is the act of assisting or stimulating respiration, a metabolic process referring to the overall exchange of gases in the body by pulmonary ventilation, external respiration, and internal respiration...
of animals were from Andreas Vesalius (1514–1564) of Brussels. In his landmark book published in 1543, De humani corporis fabrica
De humani corporis fabrica
De humani corporis fabrica libri septem is a textbook of human anatomy written by Andreas Vesalius in 1543....
, he described an experiment in which he passed a reed
Reed (plant)
Reed is a generic polyphyletic botanical term used to describe numerous tall, grass-like plants of wet places, which are the namesake vegetation of reed beds...
into the trachea of a dying animal whose thorax had been opened and maintained ventilation by blowing into the reed intermittently. Antonio Musa Brassavola
Antonio Musa Brassavola
Antonio Musa Brassavola was an Italian physician and one of the most famous of his time. He studied under Niccolò Leoniceno and Manardi. He was the friend and physician of Ercolo II, the prince of Este...
(1490–1554) of Ferrara
Ferrara
Ferrara is a city and comune in Emilia-Romagna, northern Italy, capital city of the Province of Ferrara. It is situated 50 km north-northeast of Bologna, on the Po di Volano, a branch channel of the main stream of the Po River, located 5 km north...
successfully treated a patient suffering from peritonsillar abscess
Peritonsillar abscess
Peritonsillar abscess , also called a quinsy or abbreviated as PTA is a recognised complication of tonsillitis and consists of a collection of pus beside the tonsil .-Symptoms and signs:...
by tracheotomy. Brassavola published his account in 1546; this operation has been identified as the first recorded successful tracheotomy, despite the many previous references to this operation. Towards the end of the 16th century, Hieronymus Fabricius
Hieronymus Fabricius
Hieronymus Fabricius or Girolamo Fabrizio or by his Latin name Fabricus ab Aquapendende also Girolamo Fabrizi d'Acquapendente was a pioneering anatomist and surgeon known in medical science as "The Father of Embryology."...
(1533–1619) described a useful technique for tracheotomy in his writings, although he had never actually performed the operation himself. Fabricius was the first to introduce the idea of a tracheostomy tube. In 1620 the French surgeon Nicholas Habicot (1550–1624) published a report of four successful tracheotomies. In 1714, anatomist Georg Detharding (1671–1747) of the University of Rostock
University of Rostock
The University of Rostock is the university of the city Rostock, in the German state of Mecklenburg-Vorpommern.Founded in 1419, it is the oldest and largest university in continental northern Europe and the Baltic Sea area...
performed a tracheotomy on a drowning victim.
Despite the many recorded instances of its use since antiquity
Ancient history
Ancient history is the study of the written past from the beginning of recorded human history to the Early Middle Ages. The span of recorded history is roughly 5,000 years, with Cuneiform script, the oldest discovered form of coherent writing, from the protoliterate period around the 30th century BC...
, it was not until the early 19th century that the tracheotomy finally began to be recognized as a legitimate means of treating severe airway obstruction. In 1852, French physician Armand Trousseau
Armand Trousseau
Armand Trousseau was a French internist. His contributions to medicine include Trousseau sign of malignancy, Trousseau sign of latent tetany, Trousseau-Lallemand bodies , and the truism, "use new drugs quickly, while they still work."-Biography:A native of Tours, Indre-et-Loire, Armand Trousseau...
(1801–1867) presented a series of 169 tracheotomies to the Académie Impériale de Médecine
Académie Nationale de Médecine
Académie Nationale de Médecine, or National Academy of Medicine was created in 1820 by king Louis XVIII at the urging of baron Antoine Portal. At its inception, the institution was known as the Académie Royale de Médecine...
. 158 of these were performed for the treatment of croup
Croup
Croup is a respiratory condition that is usually triggered by an acute viral infection of the upper airway. The infection leads to swelling inside the throat, which interferes with normal breathing and produces the classical symptoms of a "barking" cough, stridor, and hoarseness...
, and 11 were performed for "chronic maladies of the larynx". Between 1830 and 1855, more than 350 tracheotomies were performed in Paris, most of them at the Hôpital des Enfants Malades
Necker-Enfants Malades Hospital
The Hôpital Necker – Enfants Malades is a French teaching hospital, located in Paris, France. It is an hospital of the Assistance publique - Hôpitaux de Paris group, and is affiliated to the University of Paris Descartes...
, a public hospital
Public hospital
A public hospital or government hospital is a hospital which is owned by a government and receives government funding. This type of hospital provides medical care free of charge, the cost of which is covered by the funding the hospital receives....
, with an overall survival rate of only 20–25%. This compares with 58% of the 24 patients in Trousseau's private practice, who fared better due to greater postoperative care.
In 1871, the German surgeon Friedrich Trendelenburg
Friedrich Trendelenburg
Friedrich Trendelenburg was a German surgeon. He was son of the philosopher Friedrich Adolf Trendelenburg, father of the pharmacologist Paul Trendelenburg and grandfather of the pharmacologist Ullrich Georg Trendelenburg.Trendelenburg was born in Berlin and studied medicine at the University of...
(1844–1924) published a paper describing the first successful elective human tracheotomy to be performed for the purpose of administration of general anesthesia. In 1888, Sir Morell Mackenzie
Morell Mackenzie
Sir Morell Mackenzie was a British physician, one of the pioneers of laryngology in the United Kingdom.-Biography:...
(1837–1892) published a book discussing the indications for tracheotomy. In the early 20th century, tracheotomy became a life-saving treatment for patients afflicted with paralytic poliomyelitis
Poliomyelitis
Poliomyelitis, often called polio or infantile paralysis, is an acute viral infectious disease spread from person to person, primarily via the fecal-oral route...
who required mechanical ventilation. In 1909, Philadelphia laryngologist Chevalier Jackson
Chevalier Jackson
Chevalier Jackson was a laryngologist.Jackson was born in Pittsburgh, Pennsylvania. He went to school at the Western University of Pennsylvania from 1879 to 1883, and received his MD from Jefferson Medical College. He also studied laryngology in England.His work reduced the risks involved in a...
(1865–1958) described a technique for tracheotomy that is used to this day.
Laryngoscopy and non-surgical techniques
Vocal pedagogy
Vocal pedagogy is the study of the art and science of voice instruction. It is used in the teaching of singing and assists in defining what singing is, how singing works, and how proper singing technique is accomplished....
named Manuel García
Manuel Patricio Rodríguez García
Manuel Patricio Rodríguez García , was a Spanish singer, music educator, and vocal pedagogue.-Biography:García was born on 17 March 1805 in the town of Zafra in Badajoz Province, Spain. His father was singer and teacher Manuel del Pópulo Vicente Rodriguez García...
(1805–1906) became the first man to view the functioning glottis in a living human. In 1858, French pediatrician Eugène Bouchut
Eugène Bouchut
Eugène Bouchut was a French physician born in Paris. He made significant contributions in several medical fields, including pediatrics, laryngology, neurology and ophthalmology.-Career:...
(1818–1891) developed a new technique for non-surgical orotracheal intubation to bypass laryngeal obstruction resulting from a diphtheria
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
-related pseudomembrane. In 1880, Scottish surgeon William Macewen
William Macewen
Sir William Macewen, CB, FRS, was a Scottish surgeon. He was a pioneer in modern brain surgery and contributed to the development of bone graft surgery, the surgical treatment of hernia and of pneumonectomy .-Career:Macewen was born near Port Bannatyne, Isle of Bute, Scotland in 1848 and studied...
(1848–1924) reported on his use of orotracheal intubation as an alternative to tracheotomy to allow a patient with glottic edema to breathe, as well as in the setting of general anesthesia with chloroform
Chloroform
Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous...
. In 1895, Alfred Kirstein (1863–1922) of Berlin first described direct visualization of the vocal cords, using an esophagoscope he had modified for this purpose; he called this device an autoscope.
In 1913, Chevalier Jackson was the first to report a high rate of success for the use of direct laryngoscopy as a means to intubate the trachea. Jackson introduced a new laryngoscope blade that incorporated a component that the operator could slide out to allow room for passage of an endotracheal tube or bronchoscope. Also in 1913, New York surgeon Henry H. Janeway (1873–1921) published results he had achieved using a laryngoscope he had recently developed. Another pioneer in this field was Sir Ivan Whiteside Magill
Ivan Magill
Sir Ivan Whiteside Magill was an Irish born anaesthetist who is famous for his involvement in much of the innovation and development in modern anaesthesia....
(1888–1986), who developed the technique of awake blind nasotracheal intubation, the Magill forceps, the Magill laryngoscope blade, and several apparati for the administration of volatile anesthetic agents. The Magill curve of an endotracheal tube is also named for Magill. Sir Robert Reynolds Macintosh
Robert Reynolds Macintosh
Sir Robert Reynolds Macintosh was a New Zealand-born anaesthetist. He was the first Professor of Anaesthetics outside United States.-Early life:...
(1897–1989) introduced a curved laryngoscope blade in 1943; the Macintosh blade remains to this day the most widely used laryngoscope blade for orotracheal intubation.
Between 1945 and 1952, optical engineers
Optical engineering
Optical engineering is the field of study that focuses on applications of optics. Optical engineers design components of optical instruments such as lenses, microscopes, telescopes, and other equipment that utilizes the properties of light. Other devices include optical sensors and measurement...
built upon the earlier work of Rudolph Schindler (1888–1968), developing the first gastrocamera. In 1964, optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
technology was applied to one of these early gastrocameras to produce the first flexible fiberoptic endoscope. Initially used in upper GI endoscopy
Esophagogastroduodenoscopy
For other expansions of the initialism "OGD", see the disambiguation page.In medicine , esophagogastroduodenoscopy is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract up to the duodenum...
, this device was first used for laryngoscopy and tracheal intubation by Peter Murphy, an English anesthetist, in 1967. The concept of using a stylet for replacing or exchanging orotracheal tubes was introduced by Finucane and Kupshik in 1978, using a central venous catheter
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...
.
By the mid-1980s, the flexible fiberoptic bronchoscope had become an indispensable instrument within the pulmonology and anesthesia communities. The digital revolution
Information Age
The Information Age, also commonly known as the Computer Age or Digital Age, is an idea that the current age will be characterized by the ability of individuals to transfer information freely, and to have instant access to knowledge that would have been difficult or impossible to find previously...
of the 21st century has brought newer technology to the art and science of tracheal intubation. Several manufacturers have developed video laryngoscopes which employ digital technology such as the CMOS
CMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...
active pixel sensor
Active pixel sensor
An active-pixel sensor is an image sensor consisting of an integrated circuit containing an array of pixel sensors, each pixel containing a photodetector and an active amplifier. There are many types of active pixel sensors including the CMOS APS used most commonly in cell phone cameras, web...
(CMOS APS) to generate a view of the glottis so that the trachea may be intubated.