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Extracorporeal membrane oxygenation is used for cardiac or respiratory failure where conventional management, including cardiopulmonary resuscitation, is not successful. Extracorporeal membrane oxygenation is a circuit comprised of a draining cannula that drains blood from the body, which is circulated in the machine, and returns to the body through a returning cannula. Traditionally, venovenous and venoarterial extracorporeal membrane oxygenation are used. During this circulation of blood, anticoagulation monitoring is essential to maintain the balance between clotting and bleeding. Potential complications include heparin-induced thrombocytopenia, neurologic complications, and sepsis. Survival after extracorporeal membrane oxygenation usage has improved in cases of cardiac arrest, cardiogenic shock, and acute respiratory distress syndrome, including COVID-19 infection. This activity highlights indications and the use of extracorporeal membrane oxygenation by the interprofessional team. Objectives: Differentiate between venovenous and venoarterial extracorporeal membrane oxygenation modalities and their indications. Select the most appropriate extracorporeal membrane oxygenation circuit configuration—venovenous, venoarterial, hybrid, or parallel—by matching cannulation strategy and flow capacity to the patient's specific oxygenation and perfusion needs. Implement evidence-based anticoagulation monitoring parameters and stepwise weaning criteria to guide the safe decannulation of patients receiving venovenous and venoarterial extracorporeal membrane oxygenation support. Collaborate with surgeons, intensivists, extracorporeal membrane oxygenation specialists, pharmacists, therapists, and psychosocial professionals to coordinate continuous extracorporeal membrane oxygenation care, simulation-based drills, and quality-improvement processes that enhance communication, patient safety, and clinical outcomes. Access free multiple choice questions on this topic.

Extracorporeal membrane oxygenation (ECMO) is a life support modality for adults and children with life-threatening cardiac and pulmonary failure that is refractory to conventional therapy or unresponsive to cardiopulmonary resuscitation (CPR).[1][2] The ECMO circuit consists of a pump and an oxygenator that temporarily replace cardiac and pulmonary function, allowing time for organ recovery.[2] According to the Extracorporeal Life Support Organization (ELSO), ECMO was used in 151,683 patients through 2020, including 45,205 neonates, 30,743 children, and 75,735 adults. In 1990, ECMO was available in 83 centers; by 2020, the number of ECMO centers had grown to 492. As of July 2024, more than 185,000 cumulative ECMO runs have been reported across over 1200 centers worldwide, reflecting the rapid global expansion of this therapy.[3][4][ECLS International Summary of Statistics] Venovenous (VV) ECMO provides respiratory support, whereas venoarterial (VA) ECMO supports both cardiac and respiratory function.[3][4] ECMO is a supportive therapy rather than a disease-modifying intervention. In 1944, Kolff and Berk demonstrated blood oxygenation using cellophane chambers in an artificial kidney. In 1953, Gibbon applied artificial oxygenation and perfusion during the first successful open-heart operation. Early oxygenators included film and bubble designs, both associated with intravascular hemolysis, systemic inflammation, platelet destruction, and embolization.[5] In 1956, Clowes and Basler developed the first prototype membrane oxygenator suitable for cardiopulmonary bypass (CPB).[6] Rashkind used a bubble oxygenator in 1965 to treat neonatal respiratory failure. In 1969, Dorson et al reported the use of a membrane oxygenator in infant CPB. Baffes et al described ECMO use during infant cardiac surgery in 1970. In 1972, Hill et al reported the first use of ECMO for adult respiratory failure, and Bartlett et al achieved the first successful neonatal ECMO case in 1975 for severe respiratory distress.[7]

In 1956, Clowes and Basler developed the first prototype membrane oxygenator suitable for cardiopulmonary bypass (CPB).[6] Rashkind used a bubble oxygenator in 1965 to treat neonatal respiratory failure. In 1969, Dorson et al reported the use of a membrane oxygenator in infant CPB. Baffes et al described ECMO use during infant cardiac surgery in 1970. In 1972, Hill et al reported the first use of ECMO for adult respiratory failure, and Bartlett et al achieved the first successful neonatal ECMO case in 1975 for severe respiratory distress.[7] From the 1980s to the early 2000s, ECMO circuits typically used either silicone membrane or polypropylene hollow fiber oxygenators.[8] These oxygenators were prone to plasma leakage, prompting the development of polymethylpentene oxygenators. The newer generation polymethylpentene models are more durable, provide improved gas exchange, and result in less blood trauma.[9][10] A recent single-center pilot study comparing 4 polymethylpentene oxygenators found low oxygenator failure rates, but notable differences in resistance and post-oxygenator PaO2, emphasizing the need to tailor device choice to patient-specific requirements during long ECMO runs.[11] Kolobow and colleagues analyzed ECMO outcomes in a National Institutes of Health trial conducted in 1981. That same year, Gattinoni et al demonstrated successful ECMO use in a large population of patients with acute respiratory distress syndrome (ARDS). By 1987, Gattinoni's group reported approximately 50% survival.[12] In 1994, a randomized controlled trial by Morris et al did not show improved outcomes with low-flow VV ECMO versus conventional ventilation in ARDS. Survival in the control group was 42%, compared to 33% in the ECMO group. Interest in ECMO resurged after publication of the CESAR trial in 2009, which randomized 180 patients across 68 centers. CESAR demonstrated significantly improved outcomes—including reduced mortality and disability—among patients with severe respiratory failure treated with ECMO versus conventional management.[13] ECMO use expanded dramatically during the COVID-19 pandemic. Large-scale ELSO registry analyses have confirmed hospital survival rates of 48% to 60% in patients with severe viral ARDS when ECMO is initiated at experienced centers.[14]

Bleeding Bleeding is the most common and life-threatening complication of ECMO, as it can lead to intracranial hemorrhage or bleeding in the lungs or gastrointestinal tract. Factors responsible for bleeding include systemic heparinization, fibrinolysis, hemodilution of clotting factors, platelet dysfunction, uremia, or hepatic dysfunction. Within minutes of initiation of ECMO, activation of the contact and fibrinolytic system and consumption and dilution of coagulant factors can occur.[53] Robinson et al reported that thrombocytopenia may result from platelet adherence to surface fibrinogen and activation, aggregation, and clumping of platelets, followed by a drop in platelet counts.[54] Aubron et al reported that 17% of VV ECMO and 34% of VA ECMO required surgery for bleeding from ECMO complications. Management of life-threatening hemorrhage may involve decreasing or stopping heparin, infusion of platelets, and administration of clotting factors such as activated factor VII. Wittenstein et al noted that factor VIIa has been associated with fatal thrombosis in several cases.[55] Stallion et al mentioned that transfusion of platelets causes only a temporary increase in platelet count.[56] Prevention is better than a cure, as proven here as well. Avoidance of invasive or surgical procedures is recommended wherever possible. Platelet count greater than 150,000/mm³, fibrinogen greater than 200 mg/L, prothrombin ratio less than 1.5, and lower ACT are recommended. Temporary cessation of heparin infusion or another anticoagulant such as bivalirudin is recommended.[41] In case of fibrinolysis, elevated D-dimer or appearance of thromboelastography is useful, and the use of antifibrinolytic such as tranexamic acid, aminocaproic acid, and aprotinin is suggested.[57][58][59] A 2022 ELSO-Registry study of greater than 29,000 adult runs showed major bleeding in 30% of cases—22% during VV support and 31% during VA support—confirming hemorrhage as the leading source of ECMO morbidity.[60] Pulmonary hemorrhage is controlled with steroids or bronchoscopy in addition to the measures mentioned above. Between 10% and 15% of patients with ARDS on ECMO develop Intracerebral hemorrhage or infarction, which is responsible for 43% of ECMO-related deaths. Plasma-free hemoglobin levels exceeding 10% indicate hemolysis in patients; therefore, frequent monitoring is recommended.[1] Intracardiac Thrombosis

Pulmonary hemorrhage is controlled with steroids or bronchoscopy in addition to the measures mentioned above. Between 10% and 15% of patients with ARDS on ECMO develop Intracerebral hemorrhage or infarction, which is responsible for 43% of ECMO-related deaths. Plasma-free hemoglobin levels exceeding 10% indicate hemolysis in patients; therefore, frequent monitoring is recommended.[1] Intracardiac Thrombosis Peripheral cannulation through the femoral artery and vein used in VA ECMO can predispose to retrograde blood flow to the ascending aorta. As a result, stasis of blood in the ventricle and inadequate left ventricular output lead to intracardiac thrombus formation. Gas Embolism With a centrifugal pump, a large negative pressure of up to 100 mm Hg is generated between the pump head and the drainage cannula. Gas embolism results from the entry of air from this part of the ECMO circuit.[26] Thromboembolism Systemic thromboembolism is an infrequent complication observed in VA ECMO more than VV ECMO. Vigilant observation of the ECMO circuit for any signs of clot formation and heparin infusion to maintain target ACT prevents thromboembolism. Mechanical Complications Clot formation in the ECMO circuit is a very common complication. Factors responsible for clot formation include pulmonary or systemic emboli, oxygenator failure, or consumption coagulopathy. To prevent clot formation, heparin-coated ECMO circuits are frequently used.[61] Heparin-Induced Thrombocytopenia Heparin-induced thrombocytopenia is an uncommon complication, particularly associated with long-term use of ECMO. Disseminated intravascular coagulation has also been reported with ECMO use. Management involves cessation of heparin infusion and switching to non-heparin anticoagulants such as bivalirudin or argatroban.[1] Neurological Complications Common neurological complications include seizures, infarctions, or intracranial hemorrhages. Unlike bleeding, a predisposition to blood clot formation increases the risk of stroke in this population.[4] Ischemic stroke or intracranial hemorrhage may occur secondary to coagulopathy, systemic heparinization, thrombocytopenia, systemic hypertension, or ligation of the carotid artery and jugular vein.[62]

Common neurological complications include seizures, infarctions, or intracranial hemorrhages. Unlike bleeding, a predisposition to blood clot formation increases the risk of stroke in this population.[4] Ischemic stroke or intracranial hemorrhage may occur secondary to coagulopathy, systemic heparinization, thrombocytopenia, systemic hypertension, or ligation of the carotid artery and jugular vein.[62] A 2023 registry analysis of 37,473 patients treated with VV ECMO documented acute brain injury in 7% (2% stroke, 4% intracranial hemorrhage); these events doubled hospital mortality, underscoring the value of systematic neuro-monitoring.[63] Renal Failure and Oliguria Acute tubular necrosis can occur in the initial phase of ECMO and may require dialysis or hemofiltration.[3] Gastrointestinal Tract Complications Gastrointestinal tract hemorrhage may occur secondary to stress, ischemia, or bleeding tendencies. Prolonged fasting or total parenteral nutrition, hemolysis, and diuretics while on ECMO may predispose to hyperbilirubinemia and biliary calculi. Sepsis ECMO represents a foreign body that increases the chance of infection. Patients with postcardiotomy cardiogenic shock are more prone to develop an infection than other patients treated with ECMO.[64] Metabolic Complications Electrolyte disturbance, hypo- or hyperglycemia, alterations in the concentration of drugs secondary to increased volume of distribution, and a decrease in liver/kidney function may also be observed. Cannula-Related Complications Potential cannula-related complications observed in VA ECMO include cannula malposition; vessel perforation; hemorrhage; incorrect location, such as venous cannula within the artery; arterial dissection; pseudoaneurysm; and limb ischemia. These complications can be life-threatening and may require cannulation revision, such as displacement of the cannula.[5] The down-flow cannula can be inserted into the superficial femoral artery during percutaneous cannulation of the common femoral artery to prevent limb ischemia. Dacron graft can be sutured to the common femoral artery, and a cannula can be inserted into the graft during open procedures.[21] In case of severe leg ischemia, if required, fasciotomy should be performed.[51] Hypoxia

Potential cannula-related complications observed in VA ECMO include cannula malposition; vessel perforation; hemorrhage; incorrect location, such as venous cannula within the artery; arterial dissection; pseudoaneurysm; and limb ischemia. These complications can be life-threatening and may require cannulation revision, such as displacement of the cannula.[5] The down-flow cannula can be inserted into the superficial femoral artery during percutaneous cannulation of the common femoral artery to prevent limb ischemia. Dacron graft can be sutured to the common femoral artery, and a cannula can be inserted into the graft during open procedures.[21] In case of severe leg ischemia, if required, fasciotomy should be performed.[51] Hypoxia In case of VA ECMO, peripheral insertion of the catheter into the femoral artery perfuses more to the lower extremities and abdominal viscera, leading to hypoxia of the upper extremities, brain, and heart. Therefore, oxygen saturation should be monitored in both the upper and lower extremities. In case of poor oxygen saturation in the upper extremities, oxygenated blood is infused into the right atrium.[1] During VV ECMO, inadequate circuit flow may cause hypoxia. Other possible causes include sepsis, recirculation, inadequate sedation, iatrogenic overheating, seizures, or overfeeding.[3] Hypotension In VA ECMO, hypotension is often due to reduced vascular tone, whereas in VV ECMO, it may result from reduced vascular tone, decreased preload, or impaired cardiac function. Sepsis is also a significant contributing factor and may necessitate inotropic support. Others Additional complications observed during ECMO resuscitation include reintubation, tracheostomy, LV distention, fatal arrhythmias, and pressure ulcers.[1][3]

In patients with SARS-CoV-2, data were collected from 40 patients aged 22 to 64 who required ECMO support in severe respiratory failure. A single-access, dual-stage right atrium to pulmonary artery cannula was used. The primary outcome was survival following safe discontinuation of ventilatory and ECMO support. All patients were successfully discontinued from ECMO support after a mean duration of 2.6 days from ECMO initiation. Thus, a single-access, dual-stage cannula offered better direct pulmonary artery flow, improved oxygenation and ventilation, and early mobility. To prevent thrombosis, all patients received systemic anticoagulation, as patients with COVID-19 are prone to developing severe thrombosis. Overall, the study showed promising outcomes with most patients surviving and being discharged home without any oxygen support. Complications were minimal, with no incidence of ischemic stroke and no requirement for inotropic support or tracheostomy. However, this study was limited to 40 subjects, single-access, dual-stage VV ECMO with early extubation. Ongoing studies are necessary to define the long-term outcomes of this approach further.[5]

Cardiovascular Management Maintenance of intravascular volume and systemic perfusion is essential. Urine output, central venous pressure, body weight, and physical signs of perfusion were used to assess the volume status. Inotropic support, such as epinephrine, norepinephrine, or dopamine, or mechanical support with peripheral Impella or percutaneous atrial septostomy should be considered to sustain a good cardiac output. Echocardiography should be performed to monitor the heart's condition, rule out thrombosis, evaluate changes in ECMO flow, or assess worsening hemodynamics. Pulmonary Management Patients on ECMO should have daily radiographs, endotracheal suctioning every 4 to 6 hours depending on the secretions, frequent posture changes, and flexible bronchoscopy when required. Renal System Management Oliguric phase: During the oliguric phase, typically within the first 24 to 48 hours of ECMO initiation, an acute inflammatory response may trigger capillary leak and intravascular volume depletion, leading to oliguria and acute tubular necrosis. Diuretic phase: The diuretic phase generally begins after 48 hours, which is the earliest sign of recovery. Diuretics are required if oliguria persists for more than 48 to 72 hours. If renal failure does not improve, continuous renal replacement therapy can be initiated. Kielstein et al reported that approximately 60% of patients on ECMO require continuous renal replacement therapy (CRRT), and 3-month survival after CRRT for acute kidney injury is 17% versus 53% without CRRT. These findings suggest that the need for CRRT in ECMO-associated acute kidney injury is associated with increased mortality. Central Nervous System Management Regular neurological examinations are recommended to prevent paralysis, and incorporating sedation vacations is encouraged. A low threshold for initiating imaging studies should be maintained in cases of clinical suspicion, and aggressive management for seizures is recommended. Infection Control Strict monitoring for signs of infection or sepsis is crucial. Obtaining pan cultures weekly or whenever infection is suspected is recommended to guide timely treatment. Hematologic Considerations

Regular neurological examinations are recommended to prevent paralysis, and incorporating sedation vacations is encouraged. A low threshold for initiating imaging studies should be maintained in cases of clinical suspicion, and aggressive management for seizures is recommended. Infection Control Strict monitoring for signs of infection or sepsis is crucial. Obtaining pan cultures weekly or whenever infection is suspected is recommended to guide timely treatment. Hematologic Considerations For patients on ECMO, maintaining a hemoglobin level above 8 g/dL is recommended. Platelet transfusion is encouraged to maintain a platelet count above 100,000/mcL. ACT should be maintained between 180 and 240 seconds to avoid bleeding complications. Nutrition, Fluid, and Electrolytes Nutrition requirements should be maintained using hyperalimentation techniques. Total parenteral nutrition delivers fluids, electrolytes, vitamins, minerals, glucose, proteins (amino acids), and often lipids (fat) into the vein. Close monitoring of fluids and electrolytes, such as potassium, magnesium, phosphorus, and ionized calcium, is advised. For the first 3 days on ECMO due to fluid resuscitation, fluid retention, and oliguria, the patient's weight is expected to increase.