Comparison of the effect of propofol and N-acetyl cysteine in preventing ischaemia-reperfusion injury.

BACKGROUND AND OBJECTIVE: The aim of this study was to compare the effects of propofol and N-acetyl cysteine (NAC) on tourniquet-induced ischaemia-reperfusion injury by determining malonyldialdehyde, ischaemia-modified albumin, lactate, blood gas and haemodynamic levels in arthroscopic knee surgery. METHODS: Sixty ASA I or II patients were randomized into three groups. Intrathecal anaesthesia was administered using 0.5% heavy bupivacaine in all patients. In group P, propofol was administered in a 0.2 mg kg(-1) bolus, followed by infusion at a rate of 2 mg kg(-1) h(-1); in group NAC, NAC was administered as an infusion at a rate of 5 mg kg(-1) h(-1), and, in group C (the control group), an equal volume of isotonic saline was administered to patients until 30 min after reperfusion. Blood samplings were obtained immediately before intrathecal anaesthesia (t1), 1 min before tourniquet release (t2), 5 min after tourniquet release (t3) and 30 min after tourniquet release (t4). RESULTS: Plasma malonyldialdehyde, ischaemia-modified albumin and lactate levels increased significantly in group C at t3 and t4 compared with the baseline values. Plasma concentrations of malonyldialdehyde, ischaemia-modified albumin and lactate in groups P and NAC were significantly lower than those in group C at t3 and t4. In blood gas analyses, pH, HCO3 and base excess were found to be significantly lower at t3 and t4 compared with t1 and t2 in group C. Comparisons between groups P and NAC revealed no significant differences. CONCLUSION: Small-dose infusions of both propofol and NAC appear to provide similar protection against ischaemia-reperfusion injury in arthroscopic knee surgery.