RESPIRATORY AND SLEEP INDUCING EFFECTS OF MIDAZOLAM AS PREMEDICANT FOR REGIONAL ANESTHESIA - COMPARISON WITH DIAZEPAM, PROMETHAZINE PETHIDINE AND PLACEBO

Abstract

The effects of respiratory depression and sleep induction produced by 0.1 mg/kg and 0.15 mg/kg of midazolam i.m. were examined in patients in whom urological interventions had to be performed under spinal anesthesia. The same parameters were evaluated for 0.2 mg/kg of diazepam i.m. as well as 50 mg/50 mg of pethidine/promethazine i.m. and placebo i.m. The major difference between 0.1 mg and 0.15 mg/kg body wt of midazolam was a more pronounced PCO2[CO2 partial pressure]-increase in the group with the higher dosage. Both dosages led to anterograde amnesia in 8 or 9 of 10 patients, respectively. No amnesia developed in the control groups. Respiratory depression and sleep induction occurred later with promethazine/pethidine (at 60 min) or diazepam (at 120 min) than with midazolam. In the diazepam and placebo group hyperventilation occurred lasting 60 and 120 min, respectively. The arterial PO2 [O2 partial pressure] decreased in all groups during the intervention. Under midazolam, the decrease was significantly higher statistically than in the control groups during the first 60 min at both dosages. Premedication with 0.1 mg/kg i.m. of midazolam was sufficient in all patients. The rapid onset of action, the sleep during the intervention and the amnesia associated with it suggest that this form of premedication is more favorable than the other procedures examined. The 0.15 mg/kg dosage of midazolam was too high: in addition to producing a stronger respiratory depression, it had the effect of rendering cooperation with some patients more difficult.