Effect of intravenous midazolam premedication on postoperative nausea and vomiting after cholecystectomy

Several drugs and techniques have been used to reduce the incidence of postoperative nausea and vomiting (PONV). However PONV continues to be a common postoperative complication. Midazolam premedication in pediatric patients has been reported to reduce the incidence of PONV. In the present study the effect of intravenous midazolam premedication on the incidence and severity of PONV was investigated in a sample of adult patients undergoing anesthesia for cholecystectomy.

Eighty-two adult patients undergoing general anesthesia for cholecystectomy were randomly divided into two groups to receive either midazolam 75 microg/kg or a same volume of normal saline intravenously fifteen minutes prior to induction of anesthesia. Incidence and severity of PONV together with the total amount of administered metoclopramide during the first postoperative day were compared between two groups.

Severity of nausea was significantly lightened in midazolam group during the first six hours after recovery period compared with placebo group (3.7 +/- 1.6 of a ten point visual analog scale vs. 4.9 +/- 2.2 in placebo group; P < 0.05). Mean number of vomiting episodes was significantly lower in midazolam group (0.4 +/- 0.7 vs. 1.1 +/- 1.4 in placebo group; P < 0.05). Midazolam group received a significantly less amount of metoclopramide during the first postoperative day (2.1 +/- 3.7 mg vs. 5.3 +/- 6.8 mg in placebo group; P < 0.05).

The results of this study suggest the effectiveness of prophylactic intravenous midazolam premedication to reduce the incidence and severity of postoperative nausea and vomiting. Possible mechanisms for this effect of midazolam may be GABA receptor antagonism, inhibition of dopamine release, and anxiolytic effects.