Prophylactic N-acetylcysteine decreases serum CRP but not PCT levels and microalbuminuria following major abdominal surgery. A prospective, randomised, double-blinded, placebo-controlled clinical trial

Objective: Our objective was to investigate whether short-term infusion of the oxygen free radical scavenger N-acetylcysteine (NAC) administered before and during extensive abdominal surgery could ameliorate the progression of early systemic inflammatory response. Design: Prospective, randomised, double-blinded, placebo-controlled clinical trial. Setting: Twenty-bed intensive care unit in a university hospital. Patients: Following written informed consent, 100 patients were randomised into NAC and placebo groups. Three patients from the NAC group and four from the placebo group withdrew before the final analysis. Intervention: The treatment group (n=47) received NAC (150 mg/kg(-1) bolus followed by a continuous infusion of 12 mg/kg(-1)/h(-1)) and the placebo group (n=46) received the same volume of 5% dextrose during surgery. Measurements and results: Serum procalcitonin (PCT), C-reactive protein (CRP) and microalbuminuria was monitored preoperatively, on admission to ICU, then daily during the first 3, postoperative days. For statistical analysis Mann Whitney and Chi-squared tests were used. Patients' clinical course was similar in each group as monitored by the Multiple Organ Dysfunction Scores. There was no significant difference between the two groups regarding PCT and microalbuminuria at any assessment point. Significantly lower CRP levels were found in the NAC group on days 1 and 2 (t(24): median: 84.5 interquartile range: [62-120] vs. 118 [86-137] mg/l; p=0.020; t(48): 136 [103-232] vs. 195 [154-252] mg/l; p=0.013, NAC vs. placebo respectively). Conclusion: In this study, short-term NAC treatment decreased CRP levels, but failed to attenuate any other inflammatory response, as monitored by serum PCT and microalbuminuria. Overall, our results do not support the routine prophylactic use of NAC as a free radical scavenger in abdominal surgery.