A NOVEL TECHNIQUE FOR CARDIOPULMONARY BYPASS USING VACUUM-SYSTEM FOR VENOUS DRAINAGE WITH PRESSURE RELIEF VALVE - AN EXPERIMENTAL-STUDY

To decrease the circuit priming volume, develop safety, and simplify t he equipment, a cardiopulmonary bypass (CPB) circuit using a vacuum su ction venous drainage system with a pressure relief valve was develope d. The efficacy of this vacuum system was compared to that of a conven tional siphon system. The system contains a powerful vacuum generator and a pressure relief valve to keep the negative pressure constant whe n blood suction is used. Using 8 mongrel dogs, the feasibility and the efficacy of this CPB system was tested. The changes in the negative p ressure in the reservoir were within 5 mm Hg whether the suction lines were switched on or off. In all animals the amount of blood in the ve nous reservoir was stable throughout bypass. The decrease of priming v olume was from 725 ml (siphon system) to 250 ml (vacuum system). At th e end of CPB, the levels of hemoglobin in the vacuum system were signi ficantly higher than those in the siphon system. These results demonst rated that this vacuum drainage system can provide simplification and a miniaturization of the cardiopulmonary bypass circuit resulting in l ow hemodilution during CPB.