Seyed Hamid Reza Faiz, Seyed Alireza Seyed Siamdoust, Poupak Rahimzadeh, Leila Houshmand

Some studies have shown that deeper anesthesia is more effective on postoperative analgesia and reduces the need for sedative drugs. This study sought to investigate the effect of depth of anesthesia on postoperative pain in laparoscopic cholecystectomy. In this double-blind clinical trial, 60 patients undergoing laparoscopic cholecystectomy were randomly divided into two groups: low bispectral index (L-BIS=35-44) and high bispectral index (H-BIS=45-55). Anesthesia protocol was the same for both groups (propofol and remifentanil). The pain intensity (at rest and during cough) was evaluated based on the visual analog scale scores in recovery and at 8, 16 and 24 hours after surgery. The mean pain score was significantly lower in patients in the L-BIS group at all examined times at rest and during cough than that in the H-BIS group. The number of patients in need of additional sedative drug in the H-BIS group in recovery was significantly more than that in the L-BIS group (27 vs 18 patients, P=0.007). The incidence of nausea in the recovery room 8 hours after the surgery was significantly less in the L-BIS group than that in the H-BIS group, while at 16 and 24 hours, no case of nausea was reported in the two groups. Given the results of this study, it seems that general anesthesia with propofol and remifentanil with L-BIS causes less need for additional analgesic drug and less nausea and vomiting compared to anesthesia with H-BIS.