British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
End-tidal concentrations of halothane and isoflurane during induction of anaesthesia in young and elderly patients.
Twenty-two young (18-32 yr) and 22 healthy elderly (60-80 yr) patients received either halothane or isoflurane for maintenance of anaesthesia during controlled ventilation. End-tidal fractional concentrations (FE) of the agents were measured for 20 min after their introduction into inspired gas and the increase in end-tidal concentrations of the two agents was compared during induction of anaesthesia using the ratios of FE to the inspired fraction (FI). ⋯ This suggests slower induction of anaesthesia in the elderly if equipotent concentrations of isoflurane are used; the clinical significance of this difference is probably small. Mean FE:FI ratios for halothane in elderly patients were similar to those in the young throughout induction of anaesthesia.