A model of venous return while utilizing vacuum assist during cardiopulmonary bypass.

In order for vacuum-assisted venous return (VAVR) to be used safely and efficiently during cardiopulmonary bypass (CPB), a full understanding of venous return is necessary. The focus of this work was to use the concepts of energy conservation and viscous energy dissipation in the development of a theoretical model of venous return utilizing vacuum assist. The effectiveness and accuracy of this model has been verified through in vitro laboratory investigations and statistical analysis. Although VAVR can provide higher flows through smaller venous cannula, vacuum assist may lead to increased levels of wall shear stress as shown in this work. The clinical implications of VAVR have yet to be investigated, but may lead to an exacerbation of the detrimental effects of CPB during cardiac surgery.