Hayashi and colleagues have studied the value of a vacuum-assisted cardiopulmonary bypass system in simplifying bypass while reducing the volume of fluid needed for pump priming. They were successful in reducing priming volume by approximately 400 mL in this small study. I am somewhat concerned with this study for several reasons. The authors claim that bypass-induced hemodilution is one of the main reasons for transfusion in cardiac surgery, but they don’t support this with reliable data. In fact, one of their references deals only with infants. Moreover, they don’t show any reduction in transfusion. By their own admission, the “simpification” gained with this system has a very dangerous tradeoff in the form of the need to monitor the suction carefully to prevent pumping air into the patient. This lethal complication disappeared from the scene many years ago with modifications of bypass equipment. I hope this novel approach doesn’t bring it back again.

– R. K. Spence.