Basic Principle
ECMO is essentially a modified artificial heart-lung machine, with a membrane lung and a blood pump at its core, acting as an artificial lung and an artificial heart, respectively.When ECMO is in operation, blood is drawn from a vein, and oxygen is absorbed and carbon dioxide is expelled through the membrane lung. The gas-exchanged blood, driven by the pump, can be returned to the veins (VV pathway) or to the arteries (VA pathway).
The former is mainly used for extracorporeal respiratory support, while the latter can be used for both extracorporeal respiratory support and cardiac support because the blood pump can replace the pumping function of the heart. When a patient's lung function is severely impaired and conventional treatment is ineffective, ECMO can take on the task of gas exchange to keep the lungs in a resting state, gaining valuable time for the patient's recovery. Similarly when a patient's heart function is severely impaired, a blood pump can replace the heart's pumping function to maintain blood circulation.
Expanded Information
Laboratory research on extracorporeal cardiopulmonary assistance began with the invention of the artificial heart-lung machine by Dr. Gibbon, who successfully used extracorporeal circulation technology for the first time in clinical cardiac surgery in 1953, which made it possible to use an artificial heart-lung machine system for prolonged cardiopulmonary assistance. Extracorporeal membrane pulmonary oxygenation (ECMO) is actually an extended and prolonged application of cardiopulmonary bypass, and ECMO has been used to treat life-threatening respiratory failure for more than 20 years.
The initial cardiopulmonary bypass with a bubble oxygenator, which exists in direct contact with blood and gas, this device is still used in cardiac surgery, the advantage is that the operation is rapid, convenient, and inexpensive, and the disadvantage is that there is a blood-gas interface, which can cause damage to red blood cells, platelets, plasma proteins and other blood components, and the use of more than a few hours, hemolysis, thrombocytopenia, plasma protein denaturation, and so on, may occur. protein denaturation.
Membrane oxygenators appeared from 1960 to 1970, and anticoagulation control technology was perfected from 1965 to 1975, which made the prolonged use of cardiopulmonary resuscitation possible. Membrane oxygenators separate the blood and gas phases with a semipermeable membrane, which protects the red blood cells and platelets, and makes it possible to perform ECMO safely for a longer period of time.
Based on a large number of experiments, prolonged extracorporeal cardiopulmonary assistance began to be tried in clinical practice in the late 1960s. 1971 Dr. Hill first used ECMO to treat a 24-year-old male patient with progressive exacerbation of respiratory failure due to multiple traumas, and the patient was removed from the danger and resuscitated successfully after 75 hours of ECMO treatment. 1975 Bartlett In 1975, Dr. Bartlett used ECMO to treat a newborn with persistent fetal circulation for the first time. Since then, experience with ECMO in neonates has increased rapidly, and ECMO is now considered the standard treatment for severe respiratory failure in neonates and infants.
In 1980, the U.S. NIH (National Institutes of Health) reported the results of the first prospective, randomized study of extracorporeal cardiopulmonary assistance for respiratory failure in adult patients, which was completed by nine centers, with an original plan of 300 patients, but after 92 patients, the study was stopped because the results showed that mortality rates in both the ECMO trial group and the control group (the conventional ventilation group) were less than
The study was stopped because the results showed that the mortality rate was less than 10% in both the ECMO trial group and the control group (conventional ventilation), and they judged that the results would not change if they continued with the 300 patients.
They found that although most of the causes of death were related to complications, the lungs were all found to have extensive and significant irreversible fibrotic changes at autopsy. They therefore concluded that the main problem with the high mortality rate in the ECMO-treated group was not the technique but the irreversible lesions in the lung parenchyma. Early results of ECMO therapy applied to infants and children suffering from severe refractory respiratory failure also vary widely in terms of success rates, with many infants having underdeveloped lungs and therefore low ECMO success rates.
Most deaths during early ECMO therapy are due to hemorrhage (especially intracranial hemorrhage), which is associated with the application of high doses of heparin.ECMO is a complex therapy that requires the management of specialized and extensively trained technicians, and the inexperience of the personnel in the early phases therefore also affects the outcome of ECMO therapy.
Baidu Encyclopedia - ECMO - extracorporeal membrane pulmonary oxygenation