Effect of intraoperative depth of anesthesia on postoperative pain and analgesic requirement: A randomized...

Intraoperative depth of anesthesia may affect postoperative pain relief. This prospective, randomized, and observer-blinded study assessed the effect of intraoperative depth of anesthesia on the postoperative pain and analgesic requirements in patients undergoing laparoscopic cholecystectomy.

A total of 80 patients were randomly divided into two groups of 40 each. A standard technique for anesthesia was followed in all patients. Depth of anesthesia was monitored by bispectral index (BIS) and adjusted with 0.5 to 1.5% isoflurane in group S by addition of propofol in group B, if required, to maintain a BIS value of 45 to 40. Postoperative analgesia was provided by tramadol 1 mg/kg every 6 hours and rescue analgesia by morphine boluses. Postoperative pain was assessed by Visual analogue scale score at 0, 8, 16, and 24 hours.

The demographic characteristics were comparable in both groups. The mean BIS value in Group S was 63.32 ± 11.43 and 45.06 ± 15.31 in Group B, well in the range of 40 to 60, reflecting adequate hypnotic effect for general anesthesia. The mean arterial pressure was low in group B throughout the surgery (P<0.05-0.001). The pain score were lower in group B at 0 and 8 hours postoperatively when compared with group S (P<0.05). The rescue analgesic requirement was less in group B, compared with group S (P<0.05).

Maintaining BIS to a value of 45 to 40 throughout the surgery results in better postoperative pain relief and decreased requirement of rescue analgesic without any untoward effect.