Clinical Pearls of Venoarterial Extracorporeal Membrane Oxygenation for Cardiogenic Shock

Abstract

Extracorporeal membrane oxygenation (ECMO) is a technique that uses a pump to drain blood from a body, circulate blood through a membrane lung, and return the oxygenated blood back into the body. Venoarterial (VA) ECMO is a simplified version of the heart-lung machine that assists native pulmonary and/or cardiac function. VA ECMO is composed of a drainage cannula in the venous system and a return cannula in the arterial system. Because VA ECMO can increase tissue perfusion by increasing the arterial blood flow, it is used to treat medically refractory cardiogenic shock or cardiac arrest. VA ECMO has a distinct physiology that is referred to as differential flows. It can cause several complications such as left ventricular distension with pulmonary edema, distal limb ischemia, bleeding, and thromboembolism. Physicians who are using this technology should be knowledgeable on the prevention and management of these complications. We review the basic physiology of VA ECMO, the mechanism of complications, and the simple management of VA ECMO.

Veno-arterial extracorporeal membrane oxygenation: Special reference for use in ‘post-cardiotomy cardiogenic shock’ — A review with an Indian perspective

“…VA-ECMO drains blood from the venous system and inputs into the arterial system causing a reduction in RV and LV preload and improving endocardial blood flow by decreasing LV end diastolic pressure. LV afterload is increased in higher MAP states which distends the LV and leads to pulmonary congestion [ 34 ]. The higher flows via ECMO improve macro- and micro-circulation [ 35 ].…”

“…The O 2 uptake is determined by FiO 2 , gradient across membrane fibres, surface area of oxygenator and ECMO flow while sweep gas controls CO 2 elimination. As CO 2 transfer is six times faster compared to O 2 , failure to clear CO 2 indicates oxygenator failure [ 34 ]. Ischaemic damage due to shunting of pulmonary blood flow, inflammatory activation, collapsed lungs, ischaemia-reperfusion damage and passive congestion from LV distension contribute to ECMO-induced lung damage [ 37 ].…”

Pulmonary Vascular Changes in Acute Respiratory Distress Syndrome due to COVID-19

“…Therefore, interpretation and generalization of the findings become somewhat more intriguing due to complexities arising from hemodynamic, oxygenation and hematologic alterations induced by ECMO. 3 Venoarterial ECMO is known to increase afterload, left ventricular (LV) end diastolic pressure, left atrial pressure and post-capillary venous dilatation. Furthermore, femoral arterial oxygenated flow may not reach the coronary circulation due to watershed effect (north south syndrome) and may induce LV ischemia and aggravates LV dysfunction.…”

The use of extracorporeal membrane oxygenation postcardiotomy—A systematic review

“…Reperfusion injuries may then occur when blood flow is increased, which may result in rhabdomyolysis, acute kidney injury, multiorgan failure, and systemic inflammatory response 37 . Insertion of the cannula under fluoroscopic guidance can help significantly reduce limb ischemia 38 . Frequent monitoring of cannula site will also ensure that cannula is not kinked or obstructed by thrombus 39 .…”

“…Unfractionated heparin is often used for anticoagulation to keep the circulatory system of patient to prevent thrombosis formation in the extracorporeal circulation and the patient's circulatory system. Thankfully, current ECMO circuits have almost no possibility of thrombus formation 38 . Hemolysis can also occur especially if a thrombus forms in the pump causing mechanical damage to cells resulting in hemolytic anemia.…”