Sister chromatid exchanges in lymphocytes of humans anaesthetized with isoflurane

The potential mutagenicity of isoflurane was investigated by the sister chromatid exchange (SCE) test using peripheral blood lymphocytes from patients before and after anaesthesia. Thirty patients, aged 18-59 yr (median 29.5 yr), were anaesthetized for minor orthopaedic operations with isoflurane and nitrous oxide in oxygen for 37-90 min (median 64 min). Venous blood samples were drawn before the induction of anaesthesia, immediately after completion of anaesthesia and on the following day. SCE was examined in 30 cells from each specimen. In the 30 patients, the SCE values observed immediately after completion of anaesthesia and the day after were not different statistically from the SCE values observed before the induction of anaesthesia. Separate statistical evaluation of SCE observed among the 19 non-smoking patients also revealed unchanged SCE values. In 11 cigarette-smoking patients (average 10 cigarettes per day), SCE was increased the day after operation when compared with SCE before the induction of anaesthesia (P less than 0.02). This might reflect differences in SCE formation attributable to the patients' smoking habits, but further studies of SCE in cigarette smokers are required to elucidate this. It was concluded that there was no indication, from the SCE test, of a mutagenic effect of short-term exposure to anaesthetic concentrations of isoflurane and nitrous oxide in oxygen.