Isoflurane and enflurane in long anaesthesias for plastic microsurgery

Isoflurane and enflurane as main anaesthetics at 0.5-0.7% end-tidal concentrations in 70% N2O/30% O2 supplemented with fentanyl maintained smooth basal anaesthesia in ASA I-II patients during long (6-11 h) plastic surgery (n = 7 + 6) as well as during shorter (2-4 h) operations (n = 5 + 5). There were no statistically significant differences in haemodynamic parameters between isoflurane and enflurane patients, although mean arterial pressure was somewhat lower and heart rate higher in the isoflurane patients during the course of long anaesthesias. Both isoflurane and enflurane patients had to be given extra colloids and occasionally vasodilators to maintain peripheral temperature during the long anaesthesias. No clinically adverse renal or hepatic effects were seen, but the liver enzyme activities of four isoflurane and enflurane patients increased after the long anaesthesias. The highest serum inorganic fluoride concentration was 44 mumol/l in the enflurane patients and 5.6 mumol/l in the isoflurane patients.