The effects of
naloxone were studied in 82 patients undergoing intracranial surgery under general anaesthesia with
fentanyl or
phenoperidine. After the operation was finished the patients' alertness, sensitivity to
pain, blood pressure, pulse rate, respiratory rate, tidal and minute volume were recorded parallel with arterial blood gas analyses prior to and immediately after the administration of varying amounts of
naloxone i.v. in a single dose. These parameters were also repeatedly controlled for several hours in the postoperative period. The results show that a single i.v.
naloxone dose of 1 mug/kg b.w. is effective in the rapid and definite reversal of the
respiratory depression caused by the
analgesics. This dose was neither correlated to the total amount of
analgesics given, nor to the time period which elapsed between the last dose of the
analgesic drug and the administration of
naloxone. No side effects or complications were encountered when the indicated doses of
naloxone were given. It is concluded that, even in a small single dose,
naloxone effectively antagonises the
respiratory depression caused by
fentanyl and
phenoperidine without totally eliminating the immediate postoperative
analgesic effects of these agents.