High dose propofol enhances red cell antioxidant capacity during CPB in humans

Purpose: To compare low vs high dose propofol and isoflurane on red cell RB C antioxidant capacity in patients during aortocoronary bypass surgery (ACB P). Methods: Twenty-one patients, for ACBP were anesthetized with sufentanil 0. 5-10 mu g.kg(-1) and isoflurane 0-2%; ISO = control; n=7), or sufentanil 0. 3 mu g.kg(-1), propofol 1-2.5 mg.kg(-1) bolus then 100 mu g.kg(-1) min(-1) before, and 50 mu g.kg(-1).min(-1) during CPB (LO; n=7), or sufentanil 0.3 mu g.kg(-1), propofol 2-2.5 mg.kg(-1) bolus then 200 mu g.k(-1).min(-1) (HI ; n=7). Venous blood was drawn pre- and post-induction, after 30 min CPB, 5 , 10, and 30 min of reperfusion, and 120 min post-CPB to measure red cell a ntioxidant capacity (malondialdehyde (MDA) production in response to oxidat ive challenge with t-butyl hydrogen peroxide) and plasma propofol concentra tion. Preinduction blood samples were analyzed for antioxidant effects of n itrates on red cells. The tBHP concentration response-curves for RBC MDA in ISO, LO and HI were determined. Results: Preoperative nitrate therapy did not effect RBC MDA production. Pe rioperative RBC MDA production was similar in ISO and LO groups. Sustained intraoperative decrease in RBC MDA was seen with propofol 8.0 +/- 2.4 - 11. 8 +/- 4.5 mu g.ml(-1) in HI (P < 0.05-0.0001). MDA production vs log plasma propofol concentration was linear in HI dose. Conclusions: During CPB, RBC antioxidant capacity is enhanced and maintaine d with HI dose propofol. Propofol, at this dose, may prove useful in protec ting against cardiopulmonary ischemia-reperfusion injury associated with AC BP.