Extracorporeal membrane oxygenation
Overview
- Abbreviation: ECMO
- Extracorporeal life support (ECLS) becoming a more common term
- Extracorporeal circuit that oxygenates blood and removes carbon dioxide (functions as an out-of-body lung)
- Can be high flow or low flow
- Similar (but not identical) to cardiopulmonary bypass machine
- Requires lower levels of anticoagulation and allows longer duration of treatment (time on pump)
- Emerging therapy in Emergency Medicine (eCPR) but not yet well studied in this context
Types
- Veno-venous (VV)
- Most common
- Blood drained from central vein → oxygenator → vein near RA
- Supports severe respiratory failure without cardiac dysfunction
- Veno-arterial (VA): can be peripheral or central
- Blood drained from central vein → oxygenator → aorta
- Supports cardiac failure with or without respiratory failure
- Veno-pulmonary artery
- Blood drained from central vein → oxygenator → pulmonary artery
- Short term right ventricular/respiratory support after LVAD placement
- Hybrid (VVA or VAV)
Indications
- Acute, severe respiratory or cardiac failure + REVERSIBLE cause + refractory to usual treatment + high risk of death
- Poor gas exchange
- Compliance < 0.5ml/cmH20/kg
- P:F Ratio <100
- Shunt fraction >30%
- Veno-venous (VV)
- Pneumonia, ARDS, acute GVHD, pulmonary contusion, smoke inhalation, status asthmaticus, airway obstruction, drowning, bridge to lung transplant
- Veno-arterial (VA)
- Massive PE, nonischemic cardiogenic shock, failure of transplanted heart or heart-lung, cardiac or great vessel trauma, massive pulmonary hemorrhage/trauma, sepsis, anaphylaxis, drug overdose, bridge to LVAD
Contraindications
- Absolute
- unwitnessed cardiac arrest
- non-reversible, progressive cardiac disease in a patient who is not a transplant candidate
- non-reversible, progressive respiratory disease
- severe, chronic pulmonary hypertension
- advanced cancer
- Relative
- older than 75 years
- multisystem trauma
- CNS injury
- multiple organ failure
- VV
- unsupported cardiac failure, cardiac arrest, severe pulmonary hypertension, significant immunosupression
- VA
- Aortic dissection or severe aortic regurgitation
Equipment Needed
Procedure
Complications
- Clot formation
- Bleeding
- Suck down and kicking (vessel collapse around access cannula)
- Circut rupture, deccannulation, oxygenator failure, pump failure
- VA can → left ventricle overdistension → cardiac damage, pulmonary bleed or infarction, aortic thrombosis, cardiac or cerebral hypoxia
- North-South syndrome (cephalad hypoxia/cyanosis) may occur in patients with femoral-femoral cannulation for VA support