How I manage differential gas exchange in peripheral venoarterial extracorporeal membrane oxygenation

Table 1 Summary of venoarterial ECMO scenarios with recommended management

	Scenario 1	Scenario 2	Scenario 3
Upper body Oxygenation	High	Low	Normal
Upper body PaCO₂	Normal¹	Normal/high³	Normal/high⁴
Upper body pH	Normal²	Normal/low³	High
Lower body Oxygenation	High	High	High
Lower body PaCO₂	Normal¹	Normal¹	High
Lower Body pH	Normal²	Normal¹	Low
Upper/lower body pH ratio	1	< 1	> 1
Management	Adjust sweep as needed to maintain adequate upper body pH and PaCO₂	ECMO circuit reconfiguration to VAV ECMO or upper body VA ECMO	Increase sweep, creating lower body alkalemia in order to prompt the kidneys to eliminate bicarbonate

ECMO extracorporeal membrane oxygenation, PaCO₂ partial pressure of carbon dioxide in arterial blood, VA venoarterial, VAV venoarterial venous
¹Assuming sweep is adjusted to a normal pH
²In the absence of an independent metabolic acidosis or alkalosis
³Depending on how well preserved or impaired native lung ventilation may be
⁴Upper body PaCO₂ may be high as a compensatory response to the metabolic alkalosis

ISSN: 1364-8535