The antagonist effect of naloxone hydrochloride after neuroleptanaesthesia during neurosurgery.

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.