Clonidine Administered as an Axillary Block Does Not Affect Postoperative Pain When Given as the Sole Analgesic

Used as the sole analgesic, clonidine produces analgesia after epidural, intrathecal, and intraarticular administration.We conducted this double-blinded study to determine whether clonidine has analgesic effects when administered into the brachial plexus sheath. At the conclusion of hand or forearm surgery, performed under axillary brachial plexus block, 45 patients were randomly divided into three groups of 15 each to receive, through an axillary catheter, 15 mL of saline (Group Saline), clonidine 150 [micro sign]g in 15 mL of saline (Group Clonidine), or bupivacaine 15 mL (Group Bupivacaine). The analgesic effects of the three solutions were evaluated for 6 h. Times to onset of pain and to first analgesic request were longer, and the total dose of pain medication was smaller in Group Bupivacaine compared with the other groups. Visual analog scores were significantly lower in Group Bupivacaine. There was no significant difference in time to onset of pain, time to first analgesic request, total dose of pain medication, and visual analog scores between Group Saline and Group Clonidine at any time. We conclude that the administration of clonidine 150 [micro sign]g into the brachial plexus sheath does not prolong the onset of postoperative pain. Implications: Used as the sole analgesic, clonidine produces analgesia after epidural, intrathecal, and intraarticular administration. It also prolongs the analgesic effect of brachial plexus block when mixed with local anesthetics. In this study, the administration of clonidine 150 [micro sign]g alone into the brachial plexus sheath did not produce postoperative analgesia. (Anesth Analg 1999;88:1109-12)