What is ECMO:

Extracorporeal Membrane Oxygenation (ECMO) is form of prolonged cardiorespiratory bypass that is used to support patients with potentially reversible respiratory and/or cardiac failure that is unresponsive to maximal conventional therapy.

Types of ECMO:

Veno-Venous (VV) ECMO

• Veno-Venous ECMO removes deoxygenated blood from the venous circulation, adds oxygen and removes carbon dioxide, then pumps the freshly oxygenated blood back into the venous system where it is then pumped through the respiratory circulation by the right heart and out to the body by the left heart.
• Since the blood is both removed and reinserted into the venous system, the body relies on the heart to continue to provide adequate cardiac output. VV ECMO is therefore used mostly for respiratory failure but not for cardiac failure.

Veno-Arterial (VA) ECMO:

• Veno-Arterial ECMO removes deoxygenated blood from the venous circulation, adds oxygen and removes carbon dioxide, then pumps the freshly oxygenated blood back into the arterial system.
• Since the blood is removed from the venous system but pumped back to the arterial system, both the pulmonary circulation and both cardiac ventricles are bypassed and the heart is not needed to provide adequate cardiac output. VA ECMO can therefore be used for respiratory failure, cardiac failure, or for combined failure of both organs.
• 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?