Atropine increases inspiratory flow during enflurane anaesthesia after pethidine premedication.

The effects of atropine i.v. on inspired volume and occlusion pressure were measured in three groups of patients. Group PE received premedication with pethidine 50 mg and promethazine 12.5 mg i.m., and anaesthesia was provided by 2% enflurane in 67% nitrous oxide. Group TE received temazepam 20 mg orally for premedication and similar anaesthesia. Group TH received temazepam premedication and 1% halothane in 67% nitrous oxide. Atropine 0.02 mg kg-1 i.v. increased significantly the inspiratory flow in the first 1 s of inspiration, and this effect was greater in the group that received pethidine (9% increase in flow). However, occlusion pressure did not change, and minute volume was not altered. The results suggest that atropine increases inspiratory flow after pethidine premedication without increasing the force developed during inspiration, possibly by bronchodilatation.