What it is

Prolonged form of bypass used to support patients w/ potentially reversible respiratory or cardiac failure unresponsive to maximal conventional therapy

Veno-venous (VV) ECMO

  • Used mostly for respiratory failure

Oxygenated blood returns to pt’s venous circulation

Veno-arterial (VA) ECMO

  • Used for cardiac and respiratory failure
  • Oxygenated blood returns to pt’s arterial circulation
  • Disadvantages include potential for systemic air/clot embolization and ligation of carotid artery

How it works

  • Tubing – carries blood
  • Collapsible reservoir/ bladder – captures air bubbles or clots, used for drug administration
  • Pump drives blood through circuit, oxygenator
    • Roller pump for neonates, centrifugal for all others 
  • Membrane oxygenator – artificial lung
    • CO2 removal requires 10% cardiac output as flow
    • CO2 removal function of sweep gas flow rate
    • O2 delivery dependent on blood flow rate, Hgb, Sats 
  • Heater – warms blood prior to return to pt’s body

VA Goal Flow Rates

  • Infants 100 cc/kg/min
  • Children 75 cc/kg/min
  • Adults 50 cc/kg/min

VV Goal Flow 120% VA

General eligibility guidelines for pediatric ECMO

  • Ventilator support of < 7 days duration
  • PIP > 35 cm H20, PEEP > 10 cm H20, MAP > 18 cm H20
  • Oxygenation index > 40
  • PaO2 / FiO2 < 150
  • Failure of other therapies
    • High frequency ventilation
    • Surfactant
    • Permissive hypercapnia
    • Inhaled nitric oxide 

Complications

  • Bleeding
    • Heparin inhibits clotting, Heparin does not cause bleeding
    • Cannulae site most common. Needs stitch, not sand bag
    • Platelet consumption not as common with modern oxygenators
    • Elevated plasma free hgb implies hemolysis
      • Hemolysis from cavitation in pump, at cannulae 
    • Follow ACT, plasma free Hgb, plt, fibrinogen, ATIII, TEG
    • Generally keep plt > 80,000 and Hct ~ 40 
  • Infection – Abx as indicated. No need for cannula directed abx
  • Air/ Clot embolism

Things to know and report

  • Blood Flow rate (Liters per min)
  • Sweep rate (Liters per min).
  • Negative Venous Drainage Pressures
  • Pre and Post Oxygenator Pressures
  • ACT
  • Heparin dose
  • Circuit condition – any clots / fibrin strands?