Anaesthesia was induced by sevoflurane in oxygen. Cisatracurium 0.15 mg kg-1 was administered after loss of the lash reﬂex, then ventilated manually until the amplitude of T1 decreased to 0. Intubation was performed and switched to mechanical ventilation with a fresh gas flow of 2 L min-1. Anesthesia was maintained by sevoflurane or sevoflurane+60% nitrous oxide respectively. The surgical incision was performed at least 30 min after tracheal intubation, provided that the predetermined end-tidal sevoflurane concentration had been constant for at least 30 min and that the difference between inspired and end-tidal concentrations was less than 10%.