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

Background: The perioperative effects of intrathecal and epidural clonidine combined with local anesthetic were evaluated in 60 patients undergoing hip arthroplasty. Methods: 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 µg 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 µg h−1. Sensory block was assessed with light touch, pinprick, transcutaneous electrical stimulation at T12 and L2 dermatomes, and perception of thermal stimuli. Results: 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