EDECMO Podcast 67: Da DO2: Fundamental ECMO Physiology with Sage Whitmore
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Oct 14, 2020 
Sage Whitmore, an ED intensivist trained in ECMO and extracorporeal life support educator. He walks through DO2 vs VO2 basics and how VA ECMO substitutes native oxygen delivery. Short segments cover manipulating ECMO flow and hemoglobin, differential hypoxia, loss of pulsatility effects, avoiding cerebral hyperoxia, circuit pressures, LV afterload and venting, and practical monitoring strategies.
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DO2-VO2 Relationship Is Central To ECMO Physiology
- Oxygen delivery (DO2) must match consumption (VO2) at roughly a 5:1 ratio for normal physiology.
- Sage Whitmore explains stress increases VO2 and cardiac output rises to maintain DO2-VO2, but failing hearts can't compensate and lactate rises when ratio falls toward 2:1.
Use ECMO Flow To Replace Native Oxygen Delivery
- In ECPR you effectively replace native DO2 by pumping, oxygenating, and returning blood under pressure into the arterial tree.
- Sage Whitmore advises focusing on pump flow and membrane oxygenation to restore organ perfusion when native output is absent.
Peripheral ECMO Can Cause North South Syndrome
- Peripheral VA ECMO usually provides a mix of ECMO and native cardiopulmonary flow, not total bypass once the heart recovers.
- Sage Whitmore warns of differential hypoxia (north-south syndrome) when native lungs fail and LV ejects poorly oxygenated blood to coronaries and brain.
