Effect of sevoflurane concentration on inhalation induction of anaesthesiain the elderly

We have conducted a randomized, double-blind comparison of 4% and 8% sevofl urane for induction of anaesthesia in unpremedicated patients aged more tha n 60 yr. Sevoflurane was inhaled in 50% nitrous oxide using a vital capacit y breath technique, and mean, systolic and diastolic arterial pressures and heart rate were monitored continuously using a Finapres cuff. In the 8% se voflurane group, time to successful laryngeal mask insertion was significan tly shorter (mean 168 (SD 34) s vs 226 (62) s; P < 0.01) and achieved more often at the first attempt than in the 4% sevoflurane group. Arterial press ures were lower in the 8% group, but this was not significant. No patient h ad apnoea lasting longer than I min. A total of 69% of patients described i nduction as pleasant and 85% would choose to have it again. We conclude tha t compared with 8% sevoflurane, the use of 4% sevoflurane in the elderly re sulted in greater cardiovascular stability but at the cost of prolonged and occasionally unsuccessful induction.