CYTOKINE RESPONSES TO CARDIOPULMONARY BYPASS WITH MEMBRANE AND BUBBLE OXYGENATION

The systemic inflammatory response to cardiopulmonary bypass was assessed in 20 patients who underwent elective coronary artery bypass grafting with flat-sheet membrane oxygenation (group I; n = 10; age, 59 +/- 5 years) or bubble oxygenation (group II; n = 10; age, 62 +/- 8 years). The duration of cardiopulmonary bypass was 46 +/- 12 minutes in group I and 47 +/- 15 minutes in group II. Plasma interleukin-6, plasma interleukin-1-beta, transpulmonary leukocyte counts, pulmonary hemodynamic variables, and respiratory index were determined in all patients perioperatively. The plasma interleukin-6 response (median [range]) was similar in both groups at the end of the operation, peaked 4 hours postoperatively (99 [30 to 3201 pg/mL in group 1; 123 [21 to 300] pg/mL in group II; p > 0.05), and remained elevated 48 hours postoperatively (76 [9 to 140] pg/mL in group I; 65 [25 to 159] pg/mL in group II; p > 0.05). No significiant interleukin-1-beta response was demonstrated. Pulmonary neutrophil and lymphocyte sequestration was observed on commencement of cardiopulmonary bypass in group II but did not occur in either group on discontinuation of cardiopulmonary bypass. Pulmonary vascular resistance at the end of the operation (82 [48 to 320] dynes . s . cm-5 in group I; 119 [54 to 385] dynes . s . cm-5 in group II; p > 0.05) was similar to preoperative values (151 [30 to 327] dynes . s . cm-5 in group 1; 185 [62 to 291] dynes . s . cm-5 in group II; p > 0.05). The respiratory index at the end of the operation was similarly and significantly increased in both groups (1.26 [0.92 to 4.17] in group 1; 1.44 [0.73 to 3.30] in group II). Cardiopulmonary bypass with both membrane and bubble oxygenation was followed by a significant interleukin-6 response; pulmonary neutrophil sequestration did not occur after cardiopulmonary by. pass, although significant impairment of oxygenation was still found after perfusion of short duration.