Extracorporeal membrane oxygenation

Overview

Veno-arterial (VA) ECMO for cardiac or respiratory failure.

Veno-venous (VV) ECMO for respiratory failure.

• 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

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

External Links

• Extracorporeal Life Support Organization (ELSO)
• ED ECMO Podcast