Elimination of drugs and toxins during cardiopulmonary bypass

Cardiopulmonary bypass (CPB) creates a myriad of pharmacological and physiological changes. Some of these changes have been studied in isolated in vitro studies. Integrating an in vitro system into an in vivo process is so complicated that many pharmacological studies simply avoid the bypass period. For the most part, the studies that do examine the bypass period deal with a single drug, reporting how it does or does not produce a predicted concentration on initiation, maintenance and termination of CPB. Based on the isolated results of these studies, this review hypothesizes a model that explains how different substances interact with the CPB system. A summary of the review's findings include the following: 1) drugs with a smaller volume of distribution are more likely to be effected; 2) the pharmacokinetic effects of lipophilic drugs undergo more alterations than hydrophilic drugs; and 3) protein binding minimizes alterations of lipophilic drugs and increase alterations of hydrophilic drugs.