ECMO
Formal Definition
Extracorporeal Membrane Oxygenation — an advanced life support modality providing prolonged respiratory and/or cardiac support by mechanically circulating blood through an artificial circuit with an oxygenator and pump; venovenous (VV-ECMO) provides respiratory support only (for severe hypoxemic respiratory failure, ARDS); venoarterial (VA-ECMO) provides both cardiac and respiratory support (for cardiogenic shock, cardiac arrest); requires anticoagulation (heparin) and is managed by a specialized ECMO team in an ICU setting.
How It's Used on the Ward
"ECMO" — the last resort for a patient whose lungs or heart cannot oxygenate blood on their own despite maximal support; the machine takes blood out, puts it through a membrane where it gets oxygenated, and pumps it back in; it is bridge-to-recovery, bridge-to-transplant, or bridge-to-decision; very high risk but can be life-saving.
Example
""33-year-old pregnant woman (20 weeks) with influenza A pneumonia progressed to ARDS despite mechanical ventilation (FiO2 100%, PEEP 18, driving pressure 18). Prone positioning and neuromuscular blockade failed. PaO2 54 despite maximum vent. Transferred to ECMO center. VV-ECMO initiated via right femoral vein (drainage) and right internal jugular vein (return). Blood flow 4.5L/min, sweep gas 8L/min. Anticoagulated with heparin (target anti-Xa 0.3-0.4). ICU sedation, paralysis, prone positioning continued while on ECMO. Lung recovery expected over 2-4 weeks. Fetal monitoring maintained.""
Clinical Context
VV-ECMO indications: severe ARDS (PaO2/FiO2 <80 on FiO2 >0.8 despite optimal ventilator management), bridge to lung transplant, severe H1N1/SARS-CoV-2 pneumonia, bridge to recovery. VA-ECMO indications: cardiogenic shock (acute MI, myocarditis, post-cardiotomy), refractory VF/VT, cardiac arrest (ECPR — ECMO in cardiac arrest), post-cardiac surgery low cardiac output. Cannulation: VV (femoral vein + IJ or femoral-femoral), VA (femoral vein + femoral artery + distal perfusion catheter to prevent limb ischemia). Complications: bleeding (anticoagulation + platelet consumption), circuit clotting, stroke (hemorrhagic > ischemic in VA-ECMO), limb ischemia (VA-ECMO), infection, hemolysis. Weaning: decrease sweep gas flow to assess native lung function; decrease flows to assess native cardiac function (VA-ECMO). Survival to discharge: 40-50% for respiratory ECMO.