Respiratory effects of etomidate.

The respiratory effects of etomidate 0.3 mg/kg were studied in patients premedicated with either diazepam and atropine or papaveretum and hyoscine. The incidence of apnoea was 40% in those who received the non-narcotic premedication, compared with 27% in those who received the opiate. Those premedicated with diazepam and atropine showed a significant increase in respiratory frequency which was associated with a significant increase in minute volume 4 min after induction of anaesthesia. No such increase occurred in those premedicated with papaveretum and hyoscine. It would appear that the effects of etomidate on respiration are less than those of other i.v. induction agents, but involuntary muscle movement during induction remains a problem.