Isoflurane as a routine anaesthetic in general surgical practice

One hundred and thirty-five consecutive patients (aged 2 months to 95 yr) were anaesthetized with isoflurane for routine surgery in a District General Hospital. No major problem was encountered. One patient in the series developed ventricular extrasystoles (1 min-1), although 22 patients received a mean dose of adrenaline 3.35 micrograms kg-1. Seventeen patients had pre-existing myocardial ischaemia or angina, but there was no electrocardiographic evidence of ischaemia developing during anaesthesia. There was a mean increase in heart rate of 5 beat min-1 during anaesthesia although the maximum values reached 200 beat min-1 in children, and 150 beat min-1 in adults who received fazadinium and 140 beat min-1 in adults who did not. Supplementary doses of neuromuscular blocking drugs were seldom needed, and never for closure of peritoneum. There was a very low incidence of untoward events during recovery, although two patients early in the series showed delirium, probably as a result of sudden perception of pain following the rapid recovery. The mean half-time of wash-out of alveolar isoflurane (two patients) was 27 s. The mean volume of isoflurane administered per patient was 22 ml of liquid using fresh gas flow rates in the range 6-9 litre min-1.