Midazolam as an intravenous induction agent for general anaesthesia: a clinical trial

The peripheral and central nervous, cardiovascular and respiratory effects of midazolam 0.15 mg/kg, administered intravenously, were studied in 57 patients. Midazolam induced anaesthesia satisfactorily in 78% of the patients, the remainder required either further doses of midazolam, or alternative induction agents. There was no pain on injection. No evidence of thrombophlebitis was apparent up to 72 hours after injection. Mean systolic arterial pressure decreased from 128 mm Hg to 114 mm Hg and mean diastolic pressure decreased from 75 mm Hg to 67 mm Hg (P less than 0.005) four minutes after injection. Mean Apnoea occurred in 14 patients, with a mean onset time of 82 sec and a mean duration of 30 sec. Patients showed a decrease in mean respiratory rate from 13.7 breaths/min to 12.8 breaths/min two minutes after injection of midazolam. A larger dose than used in this study would be necessary for satisfactory use of midazolam as an induction agent for general anaesthesia.