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?