Similarity of clinical and laboratory results obtained with microporous teflon membrane oxygenator and bubble-film hybrid oxygenator

Two membrane oxygenators and a bubbler: a clinical comparison

We compared the hemocompatibility of the Polystan bubble oxygenator and the Travenol TMO and SciMed spiral-coil membrane oxygenators in 43 patients undergoing aortic valve replacement. In a subgroup of 27 patients, we collected hematological data and correlated platelet behavior with hemostasis. We found no differences in blood loss or blood (product) requirements among the groups. Platelet and erythrocyte damage was less in the membrane oxygenator groups than in the bubble oxygenator group. Differences in adenosine diphosphate-induced platelet aggregation were equivalent. Drops in this function concurred with intensified cardiotomy suction and administration of protamine. Leukocytosis after bypass was most marked in the SciMed group. Duration of bypass correlated with blood loss and blood requirements in the operating theater. Platelet counts shortly after bypass correlated negatively with duration of bypass and blood loss in the intensive care unit. Platelet function correlated with none of the factors just mentioned. We conclude that platelets and erythrocytes are preserved better by the membrane oxygenator than by the bubbler. The TMO system causes more erythrocyte damage than the SciMed oxygenator, probably due to TMO's dual-pump system. Clinical evidence for these improvements was not found, and this will be possible only when the other factors responsible for blood damage can be controlled.

A prospective randomized study of membrane versus bubble oxygenators in children

We studied 60 children, 2 weeks to 10 years old, prospectively by randomly assigning them to a SciMed membrane oxygenator or Harvey bubble oxygenator. Variables of cardiopulmonary bypass (CPB) were closely controlled: prime, circuit configuration, flow rate, and blood gases. Blood variables measured at eight intervals before, during, and after operation were as follows: seven plasma proteins, free hemoglobin, formed elements, and clotting functions. Preoperatively and postoperatively, we evaluated brain function (psychological testing), renal function (creatinine clearance), and pulmonary function (compliance changes and postoperative shunt function). Postoperative blood loss, fever, and length of hospitalization were also evaluated. We compared 302 variables by computer program. No difference (p greater than 0.05) between the two groups was found in any variable related to CPB or organ function (pulmonary, renal, or cerebral) or in hematological variables except free hemoglobin. After 5 and 60 minutes of CPB and the next day, it was significantly lower (p less than 0.05) in the group with a membrane oxygenator. Safety, cost, and convenience, not physiology, should be the major factors in considering membrane versus bubble oxygenators for cardiac operations in children.