Description
Extracorporeal membrane oxygenation (ECMO) is a life-saving mechanical support technique used in patients with severe cardiogenic shock when conventional therapies fail. In cardiogenic shock, the heart is unable to pump sufficient blood to meet the body’s needs, leading to organ hypoperfusion. Veno-arterial (VA) ECMO provides both cardiac and respiratory support by diverting blood from the venous system, oxygenating it externally, and returning it to the arterial system. This reduces the workload on the heart, improves oxygen delivery, and stabilizes hemodynamics. ECMO serves as a bridge to recovery, decision-making, heart transplantation, or long-term mechanical circulatory support. Despite its benefits, ECMO carries risks such as bleeding, thrombosis, limb ischemia, and infection. Patient selection, timing of initiation, and multidisciplinary care are critical for optimal outcomes. While ECMO has improved survival in cardiogenic shock, ongoing research is focused on refining indications, minimizing complications, and enhancing long-term recovery strategies in critically ill patients.
Summary Listen
- Cardiogenic shock is a severe form of acute heart failure characterized by pump failure despite adequate preload, leading to tissue hypoxia and organ dysfunction. Risk factors include advanced age, diabetes, peripheral vascular disease, prior cardiac surgery, and complex coronary artery disease. Causes can range from acute MI and myocarditis to arrhythmias, cardiac tamponade, and pulmonary embolism. Symptoms involve hemodynamic compromise (low blood pressure, cardiac index), end-organ dysfunction (altered mental status, oliguria), and elevated lactate, creatinine, and cardiac biomarkers.
- The progression of cardiogenic shock involves a vicious cycle of low perfusion leading to end-organ dysfunction, which in turn exacerbates cardiac dysfunction. Staging ranges from stable (A) to pre-shock (B) with abnormal hemodynamics, classic shock (C) requiring intervention, deterioration (D) with escalating support, and extreme shock (E) with circulatory collapse. Management involves initial resuscitation, including central and arterial lines, echocardiography, and coronary angiography, aiming for a MAP above 60, PCWP below 18, CVP of 8-12, urine output above 0.5 ml/kg/hr, and adequate oxygen saturation.
- Mechanical circulatory support devices are categorized by method of placement (percutaneous or surgical) and type of support (left, right, or biventricular). Potential benefits include preventing end-organ damage, maintaining organ perfusion, reducing intracardiac filling pressures, and reducing myocardial wall stress. VA-ECMO is considered for biventricular cardiogenic shock, especially when RV dysfunction is predominant.
- VA-ECMO involves venous drainage of deoxygenated blood, passage through an oxygenator, propulsion by a centrifugal pump, and arterial return of oxygenated blood. It is used in acute MI, myocarditis, cardiomyopathy, graft dysfunction, pulmonary embolism, and post-cardiotomy syndrome. Peripheral cannulation (femoral vein for drainage, femoral artery for return) is more common, often requiring a distal perfusion cannula to prevent limb ischemia.
- Early ECMO initiation (within 12-24 hours of shock onset) correlates with improved survival and neurological outcome. Challenges include bleeding, renal failure, infection, and limb ischemia. ECMO can increase left ventricular afterload, potentially worsening myocardial stress and pulmonary edema. Patient selection is crucial, as advanced stage, prolonged CPR, multi-organ failure, and severe neurological injury can worsen with ECMO.
- Recovery assessment involves daily monitoring of cardiac function via echocardiography and organ recovery. Weaning involves reducing blood flow and assessing cardiac function at lower support levels. Optimal ECMO duration is typically 5-7 days. Clinical trials are ongoing to improve patient timing, selection criteria, and outcomes.
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About the Speakers
Dr. Monalisa Mishra
Senior Consultant Critical Care Medicine Apollo Hospitals, Kolkata
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