Semiquantification of Systemic Venous Admixture During Venovenous Extracorporeal Oxygenation Via Bicaval Double-Lumen Cannula in Critically Ill Patients.

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is increasingly utilized in acute reversible cases of severe respiratory failure and as a bridge to lung transplantation. Venovenous extracorporeal membrane oxygenation using a bicaval double-lumen cannula (BCDLC) has several advantages over the traditional ECMO configuration; however, it also presents with several unique challenges. The assessment and quantification of venous admixture is difficult due to the specific position of BCDLC within the circulatory system. We describe the nature of the double-lumen bicaval venovenous ECMO cannula and relevant specific issues associated with monitoring complex details of oxygenation within different parts of circulation, including existing barriers for quantification of recirculation and venous admix. New conceptual approach to the quantification of venous admix is described. Right side echocardiographic contrast, when sequentially injected in separate superior vena cava (SVC) and inferior vena cava (IVC) venous basins, bypasses drainage ports of the catheter in double-lumen bicaval VV-ECMO configuration together with deoxygenated returning from the periphery venous blood. It was easily detectable entering right heart chambers by two- and three-dimensional echocardiography. Amount of bubbles from the agitated fluid contrast within right atrium indicates relative amount of venous admixture in relation to the returning from the oxygenator blood which is bubble free.