Perfluorocarbon Oxygen Transport

Abstract

Improvements made in current generation perfluorocarbon emulsions (PFCEs) warrant renewed interest in PFCEs as an oxygen (O2) carrying substance during cardiopulmonary bypass (CPB). Before embarking on in vivo studies of PFCEs during CPB, an in vitro study was designed to: 1) demonstrate increased O2 content attributable to PFCEs, and 2) compare O2 transfer to a PFCE crystalloid mixture by four oxygenator designs (one bubble oxygenator, two hollow fiber membrane oxygenators, and one silastic membrane oxygenator). A circuit was designed to circulate fluid between a deoxygenating device and a test oxygenator. In protocol I, either a crystalloid solution or a crystalloid PFCE mixture was circulated through bubble oxygenators at flows ranging from 0.5 to 3 l/min, and at temperatures of 4, 20, 30, or 40 degrees C. In protocol II, a crystalloid PFCE mixture was circulated at flows ranging from 0.5 to 6 l/min at temperatures of 4, 20, 30, or 40 degrees C. Four different oxygenator designs were compared using the in vitro test circuit. The comparison variables for protocols I and II were arterovenous oxygen (AVO2) difference and O2 transfer rate measured at each flow for each temperature. Protocol I showed that the AVO2 differences and O2 transfer rates were higher in the crystalloid PFCE mixture than in the crystalloid solution, although statistical comparison was precluded by the small sample size. In protocol II, the hollow fiber and silastic membrane oxygenators had higher (P < 0.05) AVO2 differences and oxygen transfer rates than the bubble oxygenators at all flows and temperatures tested. Future trials to evaluate PFCEs during cardiopulmonary bypass should use hollow fiber or silastic membrane oxygenators, rather than bubble oxygenators, to maximize transfer of O2 to the PFCE.