Postoperative ventilatory response to carbon dioxide following neurolept anaesthesia.

In order to investigate the duration of respiratory depression following neurolept anaesthesia, 21 patients who had hemilaminectomia performed were subjected to ventilation-carbon dioxide response tests by a rebreathing method in the post-operative period. Up to 3 1/2 h after start of anaesthesia all patients had a decreased ventilatory response to carbon dioxide. After this period some patients showed a normal respiratory response, while others remained depressed for up to 6 h, the period for which the investigation lasted. Most patients in the depressed group were premedicated with pethidine. We conclude that additional narcotics are contraindicated for a period of 3 1/2 h following the start of neurolept anaesthesia for surgical procedures lasting 1-2 h, while clinical control is still necessary before administration of additional narcotics within 6 h, especially if narcotics have been used as premedication.