Depression of respiratory drive by diazepam as premedication

The respiratory effects of premedication with i.v. injection of diazepam have been assessed in 10 healthy patients awaiting minor operative procedures. Measurements were recorded before and 60 min after administration of diazepam 0.14 mg kg-1. Mouth occlusion pressure (P 0.1) was used as an index of neuromuscular inspiratory drive. Minute-ventilation (VE), respiratory frequency (f) and mean inspiratory flow rate (VT/TI) were significantly reduced after diazepam. During carbon dioxide rebreathing the slopes of VE, f, VT/TI and P 0.1 with PACO2, were significantly reduced. These results confirm that i.v. diazepam produces significant respiratory depression in healthy subjects. We conclude that diazepam used under clinical conditions depresses the respiratory centre.