Effect of epidural morphine on sedation requirements during regional anesthesia.

STUDY

OBJECTIVE

To examine the effect of using analgesic doses of epidural morphine on midazolam requirements for conscious sedation during regional anesthesia.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Operating rooms at a university hospital.

PATIENTS: 20 ASA physical status II and III patients aged 50 to 70 years undergoing elective peripheral vascular reconstruction with epidural anesthesia.

INTERVENTIONS: At the beginning of surgery, 10 patients received 3 mg of epidural morphine, and the other 10 patients received normal saline epidurally. All patients received midazolam intravenously in bolus doses and as a continuous infusion to maintain a steady state of sedation throughout surgery.

MEASUREMENTS AND MAIN

RESULTS

There was no difference between the dose of midazolam required to maintain sedation in the two groups during the first 3 hours of the study. Beyond the third hour, the midazolam dose required to maintain the same level of sedation was significantly higher in the placebo group than in the epidural morphine group (p = 0.05).

CONCLUSION

An analgesic dose of epidural morphine, after a latent period of 3 hours, may decrease the dose of midazolam required for sedation using regional anesthesia.