ABSTRACT
A study was carried out to see whether the administration of a small dose of midazolam determined a reduction of the dose of fentanyl necessary for induction of anaesthesia. Sixteen patients undergoing coronary artery bypass surgery were randomly allocated to either of two groups. Patients in group M received 0.075 mg.kg-1 midazolam intravenously 3 to 5 min prior to induction with fentanyl (5 micrograms.kg-1.min-1), whereas patients in group P only received placebo. The mean dose of fentanyl administered to obtain complete loss of reaction to a painful stimulus was 20 +/- 3 micrograms.kg-1 in group M and 21.5 +/- 2.5 micrograms.kg-1 in group P (NS). However the small dose of midazolam associated with fentanyl caused a significant drop in blood pressure by 20%. After the administration of pancuronium (0.15 mg.kg-1), the patients in group P showed a significant increase in heart rate (+ 14 b.min-1), accompanied by an increase in cardiac index (+0.45 l.min-1.m-2). Pretreatment with midazolam seemed to protect the patient from this undesirable reaction. It was concluded that induction with a combination of a small dose of midazolam and fentanyl did not lead to a reduction in the dose of fentanyl necessary to obtain profound analgesia. However, it gave rise to a haemodynamic pattern quite distinct from that seen during induction with fentanyl alone.
