Postoperative analgesic effect of intravenous (i.v.) clonidine compared with clonidine administration in wound infiltration for open cholecystectomy

Objectives. This randomized double-blind study was designed to compare the postoperative analgesic effect of clonidine administered intravenously or in wound infiltration with bupivacaine. Methods. Sixty adults of ASA grade I-II undergoing open cholecystectomy were randomly allocated into three groups. Group 1 (control group) patients received wound infiltration with 30 ml of 0.25% bupivacaine at the end of surgery. Group 2 patients received 3 [mu g kg(-1) clonidine intravenously after resection of gall bladder plus wound infiltration with 30 ml of 0.25% bupivacaine. Group 3 patients received wound infiltration with 3 mu g kg(-1) clonidine with 30 ml of 0.25% bupivacaine. A standard general anaesthesia technique was used. Postoperative analgesia was provided with i.v. diclofenac and morphine on demand. Postoperative pain, number of patients requiring rescue analgesia and total morphine consumption during 24 h after operation was recorded. Results. Postoperative morphine consumption was significantly less in patients receiving clonidine by either route when compared with the control group (P<0.0001). All patients in the control group required supplemental morphine, with nine patients in the i.v. clonidine group and 11 patients in the wound infiltration group (P<0.002). Pain scores were lower at rest for 12 h and on cough for 6 h in both clonidine groups when compared with the control group (P<0.01). Patients receiving i.v. clonidine had more hypotension (P<0.01) and sedation (P<0.001) compared with other groups. Conclusions. Clonidine 3 mu g kg(-1) provided effective postoperative analgesia and reduced morphine requirement when administered intravenously or in wound infiltration with bupivacaine. However, the incidence of complications was less with wound infiltration.