Does epidural clonidine improve postoperative analgesia in major vascular surgery?

To determine the quality and duration of the analgesic and haemodynamic effects of clonidine when used as an additional analgesic for postoperative epidural analgesia in major vascular surgery.

The prospective, single-blinded study involved 60 patients randomised into three groups (20 patients each): Group BM- bupivacaine 0.125% and morphine 0.1 mg/ml; Group BC-bupivacaine 0.125% and clonidine 5 μg/ml; Group MC-morphine 0.1 mg/ml and clonidine 5 μg/ml continuously infused at 5 ml/h. The quality and duration of the analgesia measured by the Visual Analogue Scale (VAS) at rest and on movement, additional analgesia requirements, sedation scores, haemodynamic parameters and side effects (respiratory depression, motor block, toxic effects, nausea and pruritus) were recorded.

The average VAS scores at rest and on movement were significantly lower in Group MC at two, six and 24 hours following the start of epidural infusion (P<0.05). The duration of the analgesic effect after finishing the epidural infusion was significantly longer in Group MC (P<0.05). Patients from Group MC were intubated longer. Additional analgesia consumption, sedation scores and haemodynamic profiles were similar in all three groups. Pruritus was more frequent in morphine groups (P<0.05), but other side effects were similar in all three groups.

Under study conditions, clonidine added to morphine, not 0.125% bupivacaine, provided significantly better pain scores at two, six and 24 hours following the start of epidural infusion and the longest-lasting analgesia following the discontinuation of epidural infusion. However, patients from the Group MC were mechanically ventilated longer than patients from other two groups. Continuous monitoring of the patient is necessary after the administration of clonidine for epidural analgesia.