Improved analgesia with clonidine when added to local anesthetic during combined spinal‐epidural anesthesia for hip arthroplasty: a double‐blind, randomized and placebo‐controlled study

Abstract

The perioperative effects of intrathecal and epidural clonidine combined with local anesthetic were evaluated in 60 patients undergoing hip arthroplasty. This was a double-blinded study and the patients were randomized into three groups, with 20 patients in each group. All patients received spinal anesthesia with 17.5 mg of plain bupivacaine with 15 microg of clonidine (Group BC-RC) or without clonidine (Groups B-R and B-RC). Postoperatively, epidural infusion was administered in the following way: Group B-R-ropivacaine 4 mg h(-1); Groups B-RC and BC-RC: ropivacaine 4 mg h(-1) and clonidine 40 microg h(-1). Sensory block was assessed with light touch, pinprick, transcutaneous electrical stimulation at T12 and L2 dermatomes, and perception of thermal stimuli. The maximal upper level of sensory block measured by pin-prick (T6-T7) did not differ between the groups while the partial sensory block for cold and warmth were increased two dermatomes above pin-prick level in the group with intrathecal clonidine compared to the other two groups (P < 0.05). Duration of anesthesia, analgesia and motor block were longer in Group BC-RC compared to Groups B-R and B-RC (P < 0.02). Postoperatively, both VAS score on movement and PCA-morphine consumption were higher in Group B-R than in Groups B-RC and BC-RC (P < 0.01). The arterial pressure and heart rate in Groups B-RC and BC-RC were significantly lower than in Group B-R at 10-24 and 15-24 h, respectively, after spinal injection. Low-dose intrathecal clonidine provided a better quality of anesthesia and longer-lasting analgesia. Epidural clonidine-ropivacaine infusion resulted in improved postoperative analgesia but was associated with a moderate decrease in blood pressure.