Clonidine combined with small-dose bupivacaine during spinal anesthesia for inguinal herniorrhaphy: a randomized double-blinded study

Abstract

The aim of this randomized double-blinded study was to see whether the addition of small-dose clonidine to small-dose bupivacaine for spinal anesthesia prolonged the duration of postoperative analgesia and also provided a sufficient block duration that would be adequate for inguinal herniorrhaphy. We randomized 45 patients to 3 groups receiving intrathecal hyperbaric bupivacaine 6 mg combined with saline (Group B), clonidine 15 micro g (Group BC15), or clonidine 30 micro g (Group BC30); all solutions were diluted with saline to 3 mL. The sensory block level was insufficient for surgery in five patients in Group B, and these patients were given general anesthesia. Patients in Groups BC15 and BC30 had a significantly higher spread of analgesia (two to four dermatomes) than those in Group B. Two-segment regression, return of S1 sensation, and regression of motor block were significantly longer in Group BC30 than in Group B. The addition of clonidine 15 and 30 micro g to bupivacaine prolonged time to first analgesic request and decreased postoperative pain with minimal risk of hypotension. We conclude that clonidine 15 micro g with bupivacaine 6 mg produced an effective spinal anesthesia and recommend this dose for inguinal herniorrhaphy, because it did not prolong the motor block.

Implications: The addition of clonidine 15 micro g to 6 mg of hyperbaric bupivacaine increases the spread of analgesia, prolongs the time to first analgesic request, and decreases postoperative pain, compared with bupivacaine alone, during inguinal herniorrhaphy under spinal anesthesia.