Premedication with intramuscular midazolam: effect on induction time with intravenous midazolam compared to intravenous thiopentone or ketamine

Our study sought to determine whether premedication with intramuscular midazolam would decrease the time to induction of anaesthesia with intravenous midazolam, and if so whether induction of anaesthesia would be as rapid as with thiopentone or ketamine, intravenously. Eight-nine patients, ASA physical status I or II, received midazolam 0.2 mg X kg-1, thiopentone 3.0 mg X kg-1, or ketamine 2.0 mg X kg-1 intravenously 60-90 min after intramuscular injection of either midazolam 0.07 mg X kg-1 or matching placebo. Time to induction of anaesthesia or the dose required to induce anaesthesia with intravenous midazolam was not decreased by midazolam premedication. Both with or without premedication, midazolam induction time was longer than with thiopentone or ketamine. Midazolam induction was associated with a lower incidence of blood pressure increase than with ketamine induction, and a lower incidence of apnea than that with either thiopentone or ketamine.