Comparative evaluation between ascorbic acid and N-acetyl cysteine for preventing tourniquet induced ischaemic reperfusion injury during lower limb surgery, a randomized controlled trial

Background
During tourniquet induced ischemic reperfusion, reactive oxygen species and cytokines appear and cause cellular damage and remote tissue injury.
Aim
To compare the effects of preoperative intravenous infusion of N-acetyl cysteine or ascorbic acid on the production of malonyldialdehyde as a marker of oxidative stress and IL-6 and IL-8 as markers of systemic inflammation after ischemic reperfusion as primary outcomes. Also both agents were compared regarding post-deflation hemodynamic effects and post-deflation changes in arterial pH and lactic acid as secondary outcomes.
Patient and methods
60 patients, scheduled for unilateral lower extremity surgery with a pneumatic tourniquet, were included. The study was designed as a randomized controlled parallel arms superiority trial. Baseline collection of blood samples was done and then patients were randomly classified into three groups: Group A; received 1 g Ascorbic acid, group N; received 10 mg/kg NAC and group C (control group): received 100 ml saline infusion. Epidural anesthesia was administrated. Two blood samples were drawn at each assessment time. One sample for arterial blood pH and lactic acid measurement and the other blood sample was centrifuged and stored at −20 °C for subsequent analysis of MDA, IL-6 and IL-8.
Results
Levels of MDA, IL-6, and IL-8 were significantly increased in group C after tourniquet release compared with the baseline. In groups A and N, MDA did not increase over baseline values, but IL-6 and IL-8 levels were increased and their levels were significantly less than in the control group. Changes in hemodynamics, pH and serum lactate were more evident in group C than groups A and N.
Conclusion
Both N-acetyl cysteine and ascorbic acid reduce post-deflation increase in blood levels of markers of oxidative stress and markers of systemic inflammation and thus both are beneficial in preventing post-tourniquet deflation ischemic reperfusion injury in lower limb surgery.