Effect of Pre-Treatment with a Combination of Fentanyl and Midazolam for Prevention of Etomidate-Induced Myoclonus.

OBJECTIVE

Pre-treatment with either fentanyl or midazolam has previously been used to prevent etomidate-induced myoclonus (EIM). The aim of the present study was to determine the effect of pre-treatment with a combination of midazolam and fentanyl in reducing the incidence and severity of EIM.

METHODS

This prospective, randomised, double-blind study was conducted on 210 surgical patients allocated to three study groups. Group F patients received fentanyl 2 μg kg and 5 mL saline. Group M patients received midazolam 0.03 mg kg and 5 mL saline. Group FM patients received fentanyl 2 μg kg plus midazolam 0.03 mg kg. The study drugs were administered intravenously over 30 s. Five minutes after study drug administration, etomidate 0.3 mg kg was administered over 60 s. Patients were observed for 1 min for occurrence and severity of EIM.

RESULTS

The incidence of EIM was 34/70 (48.6%), 55/70 (78.6%) and 11/70 (15.7%) in groups F, M and FM, respectively (p=0.001). Myoclonus of moderate or severe grade occurred in 23/70 (32.9%), 45/70 (64.3%) and 6/70 (8.6%) in groups F, M and FM, respectively (p=0.001). Patients who experienced myoclonus exhibited a significantly higher percentage change in post-induction heart rate (p=0.02), systolic blood pressure (p=0.001) and mean blood pressure (p=0.001) from pre-induction values than those who did not.

CONCLUSION

Pre-treatment with a combination of fentanyl and midazolam is more effective than that with fentanyl or midazolam alone in reducing the incidence and severity of EIM. Myoclonus is associated with a higher post-induction haemodynamic variation.