Extracorporeal membrane oxygenation
Encyclopedia
In intensive care medicine
, extracorporeal membrane oxygenation (ECMO) is an extracorporeal
technique of providing both cardiac and respiratory
support oxygen
to patients whose heart
and lung
s are so severely diseased or damaged that they can no longer serve their function. Initial cannulation of a patient receiving ECMO is performed by a surgeon
and maintenance of the patient is the responsibility of the ECMO Specialist and gives 24/7 monitoring care during the duration of the ECMO treatment.
. It is also used with children who have respiratory syncytial virus infections. ECMO treatment provides oxygenation until their lung function has sufficiently recovered to maintain appropriate O2 saturation. It is often a last resort.
It is around 75% effective in saving the newborn's life. Newborns cannot be placed on ECMO if they are under 4.5 pounds (2 kg), because they have extremely small vessels for cannulation, thus hindering adequate flow because of limitations from cannula size and subsequent higher resistance to blood flow (compare with vascular resistance
). Therefore, the device cannot be used for most premature newborns. Newborn infants are occasionally placed on ECMO due to the lack of a fully functioning respiratory system or other birth defect, but the survival rates drops to roughly 33%.
ECMO has proven to be useful in treating some severe trauma
/polytrauma patients.
ECMO use on cadaver
s can increase the viability rate of transplanted organs.
. To initiate ECMO, cannula
e are placed in large blood vessel
s to provide access to the patient's blood. Anticoagulant
drugs, usually heparin
, are given to prevent blood clotting. The ECMO machine continuously pumps blood from the patient through a membrane oxygenator
that imitates the gas exchange
process of the lungs, i.e. it removes carbon dioxide
and adds oxygen
. Oxygenated blood is then returned to the patient. Management of the ECMO circuit is done by a team of ECMO specialists that includes intensive care unit (ICU) physician
s, physician assistant
s, perfusionist
s, Registered Nurses, respiratory therapists, and Medical Laboratory Technologists that have received training in this specialty.
system and in VV ECMO the blood is returned to the venous
system. In VV ECMO, no cardiac support is provided.
is avoided. It may therefore be life-saving for some patients. However, due to the high technical demands, cost, and risk of complications, such as bleeding under anticoagulant medication, ECMO is usually only considered as a last resort.
The time limit for a newborn on ECMO is usually around 21 days. The record for the longest survivor on ECMO occurred on January 30, 2008, when a patient at NTU hospital
, Taiwan
survived a drowning accident after 117 days of ECMO application.
may occur when the large catheter
s inserted in the neck provide fertile field for infection
. Additional risks include bleeding. In adults, ECMO survival rates are around 60%. ECMO has yet to have proven survival benefit in adults with acute respiratory distress syndrome
(ARDS). In VA ECMO, patients whose cardiac function does not recover sufficiently to be weaned from ECMO may be bridged to a ventricular assist device
(VAD) or transplant.
In infants aged less than 34 weeks of gestation several physiologic systems are not well-developed, specially the cerebral vasculature and germinal matrix
, resulting in high sensitivity to slight changes in pH
, PaO2, and intracranial pressure. Preterm infants are at unacceptably high risk for intraventricular hemorrhage
(IVH) if administered ECMO at a gestational age less than 32 weeks. Also later, given the risk of IVH, it has become standard practice to ultrasound the brain prior to administering ECMO.
Intensive care medicine
Intensive-care medicine or critical-care medicine is a branch of medicine concerned with the diagnosis and management of life threatening conditions requiring sophisticated organ support and invasive monitoring.- Overview :...
, extracorporeal membrane oxygenation (ECMO) is an extracorporeal
Extracorporeal
An extracorporeal medical procedure is a medical procedure which is performed outside the body.-Circulatory procedures:A procedure in which blood is taken from a patient's circulation to have a process applied to it before it is returned to the circulation...
technique of providing both cardiac and respiratory
Respiratory system
The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles...
support 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...
to patients whose heart
Human heart
The human heart is a muscular organ that provides a continuous blood circulation through the cardiac cycle and is one of the most vital organs in the human body...
and lung
Human lung
The human lungs are the organs of respiration in humans. Humans have two lungs, with the left being divided into two lobes and the right into three lobes. Together, the lungs contain approximately of airways and 300 to 500 million alveoli, having a total surface area of about in...
s are so severely diseased or damaged that they can no longer serve their function. Initial cannulation of a patient receiving ECMO is performed by a surgeon
Surgeon
In medicine, a surgeon is a specialist in surgery. Surgery is a broad category of invasive medical treatment that involves the cutting of a body, whether human or animal, for a specific reason such as the removal of diseased tissue or to repair a tear or breakage...
and maintenance of the patient is the responsibility of the ECMO Specialist and gives 24/7 monitoring care during the duration of the ECMO treatment.
Uses
One of the new uses is in adults and children with the H1N1 fluPandemic H1N1/09 virus
The Pandemic H1N1/09 virus is a swine origin Influenza A virus subtype H1N1 virus strain responsible for the 2009 flu pandemic. For other names see the Nomenclature section below.-Virus characteristics:...
. It is also used with children who have respiratory syncytial virus infections. ECMO treatment provides oxygenation until their lung function has sufficiently recovered to maintain appropriate O2 saturation. It is often a last resort.
It is around 75% effective in saving the newborn's life. Newborns cannot be placed on ECMO if they are under 4.5 pounds (2 kg), because they have extremely small vessels for cannulation, thus hindering adequate flow because of limitations from cannula size and subsequent higher resistance to blood flow (compare with vascular resistance
Vascular resistance
Vascular resistance is a term used to define the resistance to flow that must be overcome to push blood through the circulatory system. The resistance offered by the peripheral circulation is known as the systemic vascular resistance , while the resistance offered by the vasculature of the lungs...
). Therefore, the device cannot be used for most premature newborns. Newborn infants are occasionally placed on ECMO due to the lack of a fully functioning respiratory system or other birth defect, but the survival rates drops to roughly 33%.
ECMO has proven to be useful in treating some severe trauma
Physical trauma
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
/polytrauma patients.
ECMO use on cadaver
Cadaver
A cadaver is a dead human body.Cadaver may also refer to:* Cadaver tomb, tomb featuring an effigy in the form of a decomposing body* Cadaver , a video game* cadaver A command-line WebDAV client for Unix....
s can increase the viability rate of transplanted organs.
Procedure
An ECMO machine is similar to a heart-lung machineHeart-lung machine
Cardiopulmonary bypass is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the body. The CPB pump itself is often referred to as a heart–lung machine or "the pump"...
. To initiate ECMO, cannula
Cannula
A cannula or canula is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of data...
e are placed in large blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s to provide access to the patient's blood. Anticoagulant
Anticoagulant
An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...
drugs, usually heparin
Heparin
Heparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...
, are given to prevent blood clotting. The ECMO machine continuously pumps blood from the patient through a membrane oxygenator
Membrane oxygenator
A membrane oxygenator is a device used to add oxygen to, and remove carbon dioxide from the blood. It can be used in two principal modes: to imitate the function of the lungs in cardiopulmonary bypass , and to oxygenate blood in longer term life support, termed extracorporeal membrane oxygenation,...
that imitates the gas 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...
process of the lungs, i.e. it removes carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and adds 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...
. Oxygenated blood is then returned to the patient. Management of the ECMO circuit is done by a team of ECMO specialists that includes intensive care unit (ICU) physician
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
s, physician assistant
Physician assistant
A physician assistant/associate ' is a healthcare professional trained and licensed to practice medicine with limited supervision by a physician.-General description:...
s, perfusionist
Perfusionist
A perfusionist, also known as a clinical perfusionist or a cardiovascular perfusionist, is a specialized health professional who operates the heart-lung machine during cardiac surgery and other surgeries that require cardiopulmonary bypass....
s, Registered Nurses, respiratory therapists, and Medical Laboratory Technologists that have received training in this specialty.
Types
There are several forms of ECMO, the two most common of which are veno-arterial (VA) and veno-venous (VV). In both modalities, blood drained from the venous system is oxygenated outside of the body. In VA ECMO, this blood is returned to the arterialArtery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
system and in VV ECMO the blood is returned to the venous
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
system. In VV ECMO, no cardiac support is provided.
Duration
VV ECMO can provide sufficient oxygenation for several weeks, allowing diseased lungs to heal while the potential additional injury of aggressive mechanical ventilationMechanical 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...
is avoided. It may therefore be life-saving for some patients. However, due to the high technical demands, cost, and risk of complications, such as bleeding under anticoagulant medication, ECMO is usually only considered as a last resort.
The time limit for a newborn on ECMO is usually around 21 days. The record for the longest survivor on ECMO occurred on January 30, 2008, when a patient at NTU hospital
National Taiwan University Hospital
National Taiwan University Hospital started operations under Japanese rule in Dadaocheng on June 18, 1895, and moved to its present location in 1898. The Hospital was later annexed to the Medical School of Taipei Imperial University and renamed Taipei Imperial University Medical School Affiliated...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
survived a drowning accident after 117 days of ECMO application.
Complications
A common consequence in ECMO-treated adults is neurological injury, which may include subarachnoid hemorrhage, ischemic watershed infarctions, hypoxic-ischemic encephalopathy, unexplained coma, and brain death Fatal sepsisSepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
may occur when the large 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...
s inserted in the neck provide fertile field for infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
. Additional risks include bleeding. In adults, ECMO survival rates are around 60%. ECMO has yet to have proven survival benefit in adults with 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). In VA ECMO, patients whose cardiac function does not recover sufficiently to be weaned from ECMO may be bridged to a ventricular assist device
Ventricular assist device
A Ventricular assist device, or VAD, is a mechanical circulatory device that is used to partially or completely replace the function of a failing heart...
(VAD) or transplant.
In infants aged less than 34 weeks of gestation several physiologic systems are not well-developed, specially the cerebral vasculature and germinal matrix
Germinal matrix
In anatomy, the germinal matrix is a highly cellular and highly vascularized region in the brain from which cells migrate out during brain development. The germinal matrix is the source of both neurons and glial cells and is most active between 8 and 28 weeks gestation...
, resulting in high sensitivity to slight changes in 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...
, PaO2, and intracranial pressure. Preterm infants are at unacceptably high risk for intraventricular hemorrhage
Intraventricular hemorrhage
An intraventricular hemorrhage , often abbreviated "IVH," is a bleeding into the brain's ventricular system, where the cerebrospinal fluid is produced and circulates through towards the subarachnoid space...
(IVH) if administered ECMO at a gestational age less than 32 weeks. Also later, given the risk of IVH, it has become standard practice to ultrasound the brain prior to administering ECMO.
External links
See also
- Extracorporeal therapy