Objective: To observe the effects of high-dose aprotinin and low-dose aprotinin on the inflammatory response induced by cardiopulmonary bypass (CPB). Methods: Thirty-two patients who underwent heart valve replacement were randomized in double-blind fashion into three groups: control group (n=6), low-dose group (n=13) and high-dose group (n=13). Blood samples were taken from radial artery at three times intervals: before CPB, at the end of CPB and 2 hours after termination of CPB. Neutrophil CD11b integrin expression, plasma level of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were measured. Results: The high-dose group demonstrated no significant change in neutrophil CD11b expression and in plasma level of TNF-α, but a significant decrease in plasma level of IL-6. However, the low-dose group only demonstrated a lower CD11b expression and a lower TNF-α level at 2 h after CPB termination. Conclusion: Aprotinin has a dose-reponse effect. High-dose aprotinin is more effective in the reduction of inflammatory response induced by cardiopulmonary bypass.

0. 05), which were markedly lower in high-dose group than in low-dose group at the end of CPB and 2h after weaning from CPB (P 0. 05 ). Conclusions The high-dose aprotinin is more effective to reduce the inflammatory response to CPB than low-dose aprotinin is.