The physiological basis of clinical decision-making in venoarterial extracorporeal life support.

Venoarterial (VA) extracorporeal life support (ECLS) or extracorporeal membrane oxygenation (ECMO) as it is commonly known is used in many clinical situations to support both the pumping action of the heart and the gas exchange function of the lungs. This review hopes to refresh, in the mind of the reader, aspects of basic physiological principles that have relevance in VA ECLS therapy. The dynamics of the interaction of the machine with the patient and vice versa plays an important role in clinical outcome. An understanding of the variation from normal physiology imposed both by the machine and the disease process will help make enlightened decisions in the use of this challenging therapy. The key physiological changes during initiation, maintenance, and weaning are discussed as well as certain specific clinical scenarios.