Meptazinol--a cause of respiratory depression in general anaesthesia

The respiratory effects of meptazinol 1 mg kg-1 have been compared with those of pethidine 0.5 mg kg-1 and 1 mg kg-1 in a double-blind trial in 30 patients undergoing arthroscopic meniscectomy under general anaesthesia. Respiratory depression was seen in all treatment groups. Pethidine 1 mg kg-1 produced respiratory depression which was greater than that produced by meptazinol 1 mg kg-1. The least depressant respiratory effects were seen in the group receiving pethidine 0.5 mg kg-1. We submit that the measurement of tidal volume enhances the assessment of the respiratory effects of analgesic drugs during anaesthesia.