Guedel's classification
Encyclopedia
Guedel's classification is a means of assessing of depth of general anesthesia
introduced by Arthur Ernest Guedel
(1883-1956) in 1937.
relies on a series of physical signs of the patient
. In 1847, John Snow
(1813-1858) and Francis Plomley attempted to describe various stages of general anesthesia, but Guedel in 1937 described a detailed system which was generally accepted.
This classification was designed for use of a sole inhalational anesthetic agent, diethyl ether
(commonly referred to as simply "ether"), in patients who were usually premedicated
with morphine
and atropine
. At that time, intravenous anesthetic agents were not yet in common use, and neuromuscular-blocking drug
s were not used at all during general anesthesia. The introduction of neuromuscular blocking agents (such as succinylcholine
and tubocurarine) changed the concept of general anesthesia as it could produce temporary paralysis (a desired feature for surgery) without deep anesthesia. Most of the signs of Guedel's classification depend upon the muscular movements (including respiratory muscles), and paralyzed patients' traditional clinical signs were no longer detectable when such drugs were used.
Since 1982, ether is not used in United States. Now, because of the use of intravenous induction agents with muscle relaxants and discontinuation of ether, Guedel’s classification is regarded as obsolete. Depth of general anesthesia can now be estimated using devices such as the BIS monitor
, however, the use of BIS monitoring remains controversial.
Stage II (stage of excitement or delirium): from loss of consciousness to onset of automatic breathing. Eyelash reflex disappear but other reflexes remain intact and coughing, vomiting and struggling may occur; respiration can be irregular with breath-holding.
Stage III (stage of surgical anesthesia): from onset of automatic respiration to respiratory paralysis. It is divided into four planes:
Stage IV: from stoppage of respiration
till death. Anesthetic overdose cause medullary paralysis with respiratory arrest and vasomotor collapse. Pupils are widely dilated and muscles are relaxed.
In 1954, Joseph F. Artusio further divided the first stage in Guedel's classification into three planes.
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...
introduced by Arthur Ernest Guedel
Arthur Ernest Guedel
Arthur Ernest Guedel was an American anesthesiologist. He was known for his studies on the uptake and distribution of inhalational anesthetics, as well for defining the various stages of general anesthesia.-References:...
(1883-1956) in 1937.
History
Since general anesthesia first became widely used in late 1846, assessment of anesthetic depth was a problem. To determine the depth of anesthesia, the anesthetistAnesthesiologist
An anesthesiologist or anaesthetist is a physician trained in anesthesia and peri-operative medicine....
relies on a series of physical signs of the patient
Patient
A patient is any recipient of healthcare services. The patient is most often ill or injured and in need of treatment by a physician, advanced practice registered nurse, veterinarian, or other health care provider....
. In 1847, John Snow
John Snow (physician)
John Snow was an English physician and a leader in the adoption of anaesthesia and medical hygiene. He is considered to be one of the fathers of epidemiology, because of his work in tracing the source of a cholera outbreak in Soho, England, in 1854.-Early life and education:Snow was born 15 March...
(1813-1858) and Francis Plomley attempted to describe various stages of general anesthesia, but Guedel in 1937 described a detailed system which was generally accepted.
This classification was designed for use of a sole inhalational anesthetic agent, diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
(commonly referred to as simply "ether"), in patients who were usually premedicated
Premedication
Premedication refer to a drug treatment given to a patient before a medical procedure. These drugs are typically sedative or analgesic....
with morphine
Morphine
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...
and 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...
. At that time, intravenous anesthetic agents were not yet in common use, and 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...
s were not used at all during general anesthesia. The introduction of neuromuscular blocking agents (such as succinylcholine
Suxamethonium chloride
Suxamethonium chloride , also known as suxamethonium or succinylcholine, is a paralytic drug used to induce muscle relaxation and short-term paralysis, usually to facilitate tracheal intubation. Suxamethonium is sold under the trade names Anectine, Quelicin, and Scoline. It is used as a paralytic...
and tubocurarine) changed the concept of general anesthesia as it could produce temporary paralysis (a desired feature for surgery) without deep anesthesia. Most of the signs of Guedel's classification depend upon the muscular movements (including respiratory muscles), and paralyzed patients' traditional clinical signs were no longer detectable when such drugs were used.
Since 1982, ether is not used in United States. Now, because of the use of intravenous induction agents with muscle relaxants and discontinuation of ether, Guedel’s classification is regarded as obsolete. Depth of general anesthesia can now be estimated using devices such as the BIS monitor
Bispectral index
Bispectral index is one of several technologies which purport to monitor depth of anesthesia. BIS monitors are intended to replace or supplement Guedel's classification system for determining depth of anesthesia...
, however, the use of BIS monitoring remains controversial.
Stages of Anesthesia
Stage I (stage of analgesia or disorientation): from beginning of induction of general anesthesia to loss of consciousness.Stage II (stage of excitement or delirium): from loss of consciousness to onset of automatic breathing. Eyelash reflex disappear but other reflexes remain intact and coughing, vomiting and struggling may occur; respiration can be irregular with breath-holding.
Stage III (stage of surgical anesthesia): from onset of automatic respiration to respiratory paralysis. It is divided into four planes:
- Plane I - from onset of automatic respiration to cessation of eyeball movements. Eyelid reflex is lost, swallowing reflex disappears, marked eyeball movement may occur but conjunctival reflex is lost at the bottom of the plane
- Plane II - from cessation of eyeball movements to beginning of paralysis of intercostal muscles. Laryngeal reflex is lost although inflammation of the upper respiratory tract increases reflex irritability, corneal reflex disappears, secretion of tears increases (a useful sign of light anesthesia), respiration is automatic and regular, movement and deep breathing as a response to skin stimulation disappears.
- Plane III - from beginning to completion of intercostal muscle paralysis. Diaphragmatic respiration persists but there is progressive intercostal paralysis, pupils dilated and light reflex is abolished. The laryngeal reflex lost in plane II can still be initiated by painful stimuli arising from the dilatation of anus or cervix. This was the desired plane for surgery when muscle relaxantMuscle relaxantA muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics...
s were not used. - Plane IV - from complete intercostal paralysis to diaphragmatic paralysis (apneaApneaApnea, 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...
).
Stage IV: from stoppage of respiration
Respiratory arrest
Respiratory arrest is the cessation of breathing. It is a medical emergency and it usually is related to or coincides with a cardiac arrest. Causes include opiate overdose, head injury, anaesthesia, tetanus, or drowning...
till death. Anesthetic overdose cause medullary paralysis with respiratory arrest and vasomotor collapse. Pupils are widely dilated and muscles are relaxed.
In 1954, Joseph F. Artusio further divided the first stage in Guedel's classification into three planes.
- 1st plane The patient does not experience amnesiaAmnesiaAmnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause amnesia...
or analgesiaAnalgesicAn analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos .... - 2nd plane The patient is completely amnesic but experiences only partial analgesia
- 3rd plane The patient has complete amnesia and analgesia
See also
- Oropharyngeal airwayOropharyngeal airwayAn oropharyngeal airway is a medical device called an airway adjunct used to maintain a patent airway. It does this by preventing the tongue from covering the epiglottis, which could prevent the person from breathing...
- Anesthetic agents
- Instruments used in anesthesiologyInstruments used in anesthesiologyFollowing is a list of instruments used in the practice of anesthesia:-Instrument list:- Anesthetic machine :General anesthesia does not require the anesthetic machine, tested daily, as basic equipment...
- Anesthesia machineAnaesthetic machineThe anaesthetic machine is used by anaesthesiologists and nurse anaesthetists to support the administration of anaesthesia...
- Inhalational anestheticInhalational anaestheticAn inhalational anaesthetic is a chemical compound possessing general anaesthetic properties that can be delivered via inhalation. They are administered by anaesthetists through an anaesthesia mask, laryngeal mask airway or tracheal tube connected to some type of anaesthetic vaporiser and an...