A comparative study of duration of postoperative analgesia between epidural bupivacaine and epidural clonidine plus bupivacaine in lumbar laminectomy surgery under general anaesthesia.

A randomised prospective double-blind placebo controlled study was undertaken in 60 patients of ASA-I and II, scheduled for lumbar laminectomy under general anaesthesia using thiopentone, fentanyl, artracurium, N2O/O2 and isoflurane. After obtaining written Informed consent from all patients, they were randomly allocated to two equal groups ie, group A (n = 30) and group B (n = 30). Group A patients received clonidine 0.5 ml (75 microg) plus 5 ml 0.25% bupivacaine and group B patients received 5 ml 0.25% bupivacaine plus 0.5 ml of normal saline (NS) as a control through epidural route placed by the surgeon at the closure of the surgery. All the vital parameters were recorded at the time of epidural catheter placement and administering drugs and at 10 minutes interval thereafter till the patients were reversed with neostigmine and glycopyrrolate and then in the postanaesthetic care unit (PACU) at 15 minutes interval till the end of the study. All patients received injection diclofenac 75 mg IM as soon as they complained of pain or when the VAS score became > or = 4cm. The study ended when patients received injection diclofenac 75 mg IM as rescue analgesic. Any feature of motor block, sedation score and event of urinary retention were recorded in the PACU. Duration of postoperative analgesia was taken as the primary outcome and measured from the time of regaining full consciousness following surgery till receiving first injection of rescue analgesic in the PACU. Duration of postoperative analgesia was (546.36 +/- 11.55 minutes) in group A compared to (240.15 +/- 07.32 minutes) in group B. No clinically significant difference was found in heart rate, blood pressure, respiratory rate, oxygen saturation and motor blockade. Sedation score was slightly higher in group A, which was not significant. So small dose of clonidine (75 microg) as an adjuvant to 5 ml 0.25% bupivacaine in epidural route following lumbar laminectomy significantly prolonged postoperative analgesia and improved patient satisfaction without any clinically significant adverse reaction.