Effects of N-acetylcysteine on pulmonary function in patients undergoing coronary artery bypass surgery with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) has been implicated in causing poor pulmonary gas exchange postoperatively in patients undergoing coronary artery bypass grafting (CABG) procedures. In this prospective, randomized, double-blind, placebo-controlled study, we examined the pulmonary effects of N-acetylcysteine (NAC) in patients undergoing CABG. Twenty patients undergoing elective CABG and early tracheal extubation were randomized into two groups. Group I (ten patients) received a physiologic salt solution as a placebo in a continuous intravenous infusion for one hour before CPB and 24 hours after CPB; Group II (ten patients) received 100 mg/ kg NAC intravenously for one hour before CPB and 40 mg/kg/day at 24 hours after CPB. Perioperative hemodynamic and pulmonary data were recorded. Postoperative tracheal extubation was accomplished at the earliest appropriate time. The postoperative clinical course was similar in the two groups. Both groups exhibited significant postoperative increases in A-a oxygen gradient (p < 0.01), but patients in Group II exhibited significantly lower increases in postoperative A-a oxygen gradient (p < 0.006). Other hemodynamic and pulmonary data (pulmonary capillary wedge pressure, pulmonary vascular resistance (PVR), cardiac index (CI), shunt flow, dynamic lung compliance and static lung compliance) exhibited no differences between the groups. There was no significant difference in terms of intubation time. The malondialdehyde (MDA) increase in Group II following CPB was found to be significantly lower than in Group I (p = 0.043). This clinical study reveals that administration of NAC to patients undergoing elective CABG with CPB improves systemic oxygenation. There was no effect in other pulmonary parameters and in terms of intubation time.