Albumin in the cardiopulmonary bypass prime: how little is enough?
Previous studies have demonstrated high transoxygenator pressures with noncoated hollow-fiber membrane oxygenators. These reports have been associated with dramatic platelet count drops during cardiopulmonary bypass (CPB). It has also been shown that adding human albumin to the prime of the bypass circuit reduces, if not eliminates, these problems. This study was conducted to determine what is the smallest amount of albumin added to the prime that will still display its protective effects. Eighty patients undergoing nonemergency open-heart surgery were randomly divided into four groups. Groups I and II received the Sarns Turbo 440 oxygenator with 0.0375 g of albumin/100 ml of prime and 0.125 g of albumin/100 ml of prime, respectively, added to the pump prime. Groups III and IV received the Medtronic Maxima-PRF oxygenator with 0.0375 g of albumin/100 ml of prime and 0.125 g of albumin/100 ml of prime, respectively, added to the pump prime. Pre-CPB, on CPB (15-20 min after the initiation of bypass) and warming hemoglobin, hematocrit and platelet counts were drawn on all patients. Net platelet count drop, which accounted for hemodilutional effects, was calculated for all specimens and compared to previous results obtained from the test oxygenators without albumin in the prime. The net platelet count drops for the study groups were as follows: Sarns oxygenator with no albumin in the prime = 11.8+/-12.5%; Sarns oxygenator with 0.0375 g of albumin/100 ml prime = -3.7+/-10.8%; Sarns oxygenator with 0.125 g of albumin/100 ml prime = -2.0+/-12.6%; Medtronic oxygenator with no albumin in the prime = 20.1+/-14.5%; Medtronic oxygenator with 0.0375 g albumin/100 ml prime = -6.9+/-8.7%; and Medtronic oxygenator with 0.125 g albumin/100 ml prime = -14.0+/-12.4%. Our results illustrate that adding as little as 0.0375 g albumin/100 ml prime (3 ml of 25% solution/2000 ml of prime) to the pump prime illicits the beneficial effects of surface coating on platelet loss during CPB.