Anaesthesiologie und Reanimation
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In the present study the disposition of alfentanil after cessation of a constant rate infusion was compared with intravenous bolus injections. In 11 patients undergoing intervertebral disk surgery general anaesthesia was induced with midazolam, alfentanil and vecuronium; anaesthesia was maintained with a constant rate infusion (1.5 to 2 micrograms/kg/min, 1.0 micrograms/kg/min at the end of the infusion period) of alfentanil. The parameters of bolus injections were obtained from 5 patients undergoing lithotripter therapy; an intravenous bolus of 15 micrograms/kg was given. ⋯ There were no significant correlations between the total clearance of alfentanil and the total dose and between the duration of infusion and total clearance. The clinical implications of our study: After prolonged continuous infusions of alfentanil a significant reduction of the elimination rate has to be considered. The patients must be observed very carefully in the recovery room in order to prevent a possible respiratory depression.