Sister chromatid exchanges in cigarette smokers: effects of halothane, isoflurane or subarachnoid blockade.

In a previous study of the potential mutagenic action of isoflurane using the sister chromatid exchange (SCE) test in lymphocytes of surgical patients, it appeared that SCE increased in a group of 11 cigarette smokers, there being no effect in patients who were non-smokers. In the present study, 63 cigarette smokers were examined by the SCE test before and after minor orthopaedic operations undertaken under halothane or isoflurane anaesthesia, or subarachnoid analgesia. No significant changes of SCE were observed, and the risk of having missed a "true" increase of more than 0.6 SCE per cell was less than 1%. It was concluded that, in cigarette smokers, SCE in lymphocytes were unchanged after both general anaesthesia and subarachnoid analgesia, and that there was no indication from the SCE test of a mutagenic action of halothane, or isofurane, in nitrous oxide.