Venoarterial extracorporeal membrane oxygenation, indicated for severe cardio-respiratory failure, may result in anatomic regional differences in oxygen saturation. This depends on cannulation, hemodynamic state, and severity of respiratory failure. Differential hypoxemia, often discrete, may cause clinical problems in peripheral femoro-femoral venoarterial extracorporeal membrane oxygenation, when the upper body is perfused with low saturated blood from the heart and the lower body with well-oxygenated extracorporeal membrane oxygenation blood. The key is to diagnose and manage fulminant differential hypoxemia, that is, a state that may develop where the upper body is deprived of oxygen. We summarize physiology, assessment of diagnosis, and management of fulminant differential hypoxemia during venoarterial extracorporeal membrane oxygenation. A possible solution is implantation of an additional jugular venous return cannula. In this article, we propose an even better solution, to drain the venous blood from the superior vena cava. Drainage from the superior vena cava provides superiority to venovenoarterial configuration in terms of physiological rationale, efficiency, safety, and simplicity in clinical circuit design.

Venoarterial extracorporeal membrane oxygenation (VA‐ECMO) is indicated in reversible life‐threatening circulatory failure with or without respiratory failure. Arterial desaturation in the upper body is frequently seen in patients with peripheral arterial cannulation and severe respiratory failure. The importance of venous cannula positioning was explored in a computer simulation model and a clinical case was described. A closed‐loop real‐time simulation model has been developed including vascular segments, the heart with valves and pericardium. ECMO was simulated with a fixed flow pump and a selection of clinically relevant venous cannulation sites. A clinical case with no tidal volumes due to pneumonia and an arterial saturation of below 60% in the right hand despite VA‐ECMO flow of 4 L/min was described. The case was compared with simulation data. Changing the venous cannulation site from the inferior to the superior caval vein increased arterial saturation in the right arm from below 60% to above 80% in the patient and from 64 to 81% in the simulation model without changing ECMO flow. The patient survived, was extubated and showed no signs of hypoxic damage. We conclude that venous drainage from the superior caval vein improves upper body arterial saturation during veno‐arterial ECMO as compared with drainage solely from the inferior caval vein in patients with respiratory failure. The results from the simulation model are in agreement with the clinical scenario.

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