Abstract
The effects of small doses of midazolam (0.08mg/kg) used as a rapid sequence induction agent combined with thiamylal (4mg/kg: Group M) were compared with 4μg/kg of fentanyl combined with thiamylal 4mg/kg(Group F) or 6mg/kg of thiamylal alone(Group C). Under monitoring of the electrocardiogram and direct arterial pressure from radial artery, measurement of plasma catecholamine (epinephrine and norepinephrine) concentration as sympatho-adrenal response and blood gas analysis were done during induction of anesthesia, laryngoscopy and tracheal intubation.
In group M, increases in systolic blood pressure and heart rate following intubation were inhibited when compared with group C, Whereas significant increase in heart rate probably due to baro-reflex was observed comparing with group F. The significant elevation of plasma norepinephrine level after intubation was only observed in group C. The changes in PaO2 and PaCO2showed no differences among the groups during study period.
In this study, we demonstrated that supplementary doses of midazolam are able to reduce the dose requirement of thiamylal and to blunt circulatory responses to induction of anesthesia and tracheal intubation. Although these data confirmed the safety and efficacy of midazolam as a rapid sequence anesthetic induction agent, a careful observation should be done when used in patients with heart diseases, because of the small dose of midazolam resulting tachycardia.
