Low dose intravenous midazolam for prevention of PONV, in lower abdominal surgery--preoperative vs intraoperative administration.

BACKGROUND The aim of the present study was to compare anti-emetic efficacy of low dose midazolam premedication (35 microg/kg) 15 minutes before induction of anesthesia with midazolam (35 microg/kg) administered intravenously 30 min before conclusion of surgery, in patients undergoing lower abdominal surgery under general anesthesia. METHODS Sixty patients were assigned to one of three equal groups: Group MP (n = 20), which received intravenous midazolam 35 microg/kg in a volume of 3 ml 15 minutes before induction of anesthesia and 3 ml normal saline 30 minutes before extubation. Group MI (n = 20), which received 3 ml normal saline 15 minutes before induction of anesthesia and intravenous midazolam 35 microg/kg in a volume of 3 ml 30 minutes before extubation. Group NS (n = 20), which received 3 ml normal saline 15 minutes before induction of anesthesia plus 3 ml normal saline 30 minutes before extubation. Assessments of the occurrence of postoperative nausea and vomiting (PONV) were made at regular intervals for the first 24 h. RESULTS Incidence of PONV was significantly lower in Group MI compared with Group NS and Group MP at 6, 12, 18, and 24 hours after operation (P < 0.05). The time for the first episode of PONV was significantly higher in Group MI compared with Group NS and Group MP (P < 0.05). CONCLUSION Our results indicated that midazolam 35 microg/kg (2 mg) given intravenously 30 minutes before the end of surgery was more effective in decreasing the incidence of PONV than midazolam premedication 35 microg/kg.