The effects of propofol or sevoflurane on free radical production after tourniquet induced ischaemia-reperfusion injury during knee arthroplasty.

Background: We studied the effects of anesthesia with propofol or sevoflurane on the production of free oxygen radicals during total knee arthroplasty performed with the use of an ischemic tourniquet by measuring the levels of malondialdehyde (MDA).

Methods: We studied two groups of patients (20 patients in each group) who underwent total knee arthroplasty. To maintain anesthesia we delivered 66% nitrous oxide plus sevoflurane or propofol. Blood samples for the determination of the MDA levels were drawn before the application of the ischemic tourniquet and 5 and 30 minutes after its release.

Results: There were no differences between groups in regard to age, weight and duration of the tourniquet application. MDA levels decreased significantly in the propofol group 30 minutes after the release of the tourniquet (1.7 micromol litre(-1) vs 1.57 micromol litre(-1), Friedman's ANOVA, P = 0.007). In contrast, there was a small rise of the MDA levels in the sevoflurane group (1.82 micromol litre(-1) vs 1.96 micromol litre(-1), Friedman's ANOVA, P = 0.007).

Conclusion: Propofol may have anti-oxidant properties in orthopaedic surgery requiring tourniquet application, but sevoflurane needs further study.