Clonidine as an adjunct to intravenous regional anesthesia: A randomized, double-blind, placebo-controlled dose ranging study

Background: The addition of clonidine to lidocaine intravenous regional anesthesia (IVRA) has been previously reported toimprove postoperative analgesia in patients undergoing upper extremity surgery. Our objective was to perform a dose rangingstudy in order to determine the optimal dose of clonidine used with lidocaine in IVRA.Design & Setting: We performed a double-blinded randomized placebo-controlled study with 60 patients scheduled for electiveendoscopic carpal tunnel release under IVRA with 50 ml lidocaine 0.5%. University-affiliated outpatient surgery center. Datacollected in operating rooms, recovery room, and by telephone after discharge from surgery center.Materials & Methods: Sixty adult ASA I or II patients undergoing outpatient endoscopic carpal tunnel release under intravenousregional anesthesia.Patients were randomized into five study groups receiving different doses of clonidine in addition to 50ml 0.5% lidocaine in their IVRA. Group A received 0 mcg/kg, group B 0.25 mcg/kg, group C 0.5 mcg/kg, group D 1.0 mcg/kgand group E 1.5 mcg/kg of clonidine.Intraoperative fentanyl, recovery room pain scores, time to first postsurgical analgesic,total number of acetaminophen/codeine tablets consumed postsurgery, incidence of sedation, hypotension and bradycardia.Results & Conclusions: There was no benefit from any dose of clonidine compared to placebo. There were no clonidinerelatedside effects seen within the dose range studied. In short duration minor hand surgery, the addition of clonidine tolidocaine-based intravenous regional anesthesia provides no measurable benefit.