Minimal flow sevoflurane and isoflurane anaesthesia and impact on renal function

Background and aim Compound A generation and accumulation in sevoflurane an aesthesia is dependent on fresh gas flow. We investigated the extent of gen eration of compound A. Methods After Institutional Review Board approval and informed consent, pat ients with normal renal function were randomized to receive either sevoflur ane (n=33) or isoflurane (n=43) minimal flow anaesthesia (0.5 L min(-1)) fo r at least 2 h under standardized conditions. Compound A concentrations wer e quantified and blood and urine samples were taken to assess renal involve ment. Both groups were comparable. Results No significant differences concerning blood chemistry and urine mea surements were found. The maximum mean compound A concentration was observe d 90 min after flow reduction being 40 +/- 9 p.p.m. at a corresponding mean sevoflurane concentration of 2.1 +/- 0.5 vol%. Mean inspiratory compound A exposure was 102 +/- 33 p.p.m h(-1). Conclusion Compound A concentrations using 0.5 L min(-1) fresh gas flow and a heated absorber were higher than previously published values using an in flow of 1 L min(-1). Compound A exposure was similar to other clinical stud ies which did not show changes in renal and hepatic function.