Clonidine as an adjuvant for lidocaine in axillary brachial plexus block in patients with chronic renal failure

Clonidine is often used as an adjuvant for local anaesthetics in regional anaesthesia; however, its effects on axillary block in chronic renal failure patients have not been investigated. These effects were the focus of this study. Twenty-eight adult chronic renal failure patients (ASA physical status III) scheduled for arteriovenous fistula construction were studied in a prospective, randomized, double-blind, controlled design. All axillary block procedures were performed by the same anaesthesiologist using the nerve stimulator technique. The control group received 40 ml of lidocaine (10 mg ml(-1)) combined with 1 ml of saline, and the clonidine group received 40 ml of lidocaine (10 mg ml(-1)) mixed with 150 mu g of clonidine. Characteristics of the patients and the blocks were recorded, in addition to data on the nerves stimulated, intraoperative haemodynamic parameters, and sedative and analgesic requirements. The onset time for sensory blockade was longer in the clonidine group than in the controls (P = 0.013), and both motor and sensory blocks lasted longer in the clonidine group (P = 0.004, P < 0.001, respectively). In addition, the clonidine group had lower mean arterial pressures, heart rates and higher sedation scores compared to the controls (P < 0.05 for all). Use of clonidine (150 mu g) as adjuvant for lidocaine in axillary blocks for arteriovenous fistula construction in chronic renal failure patients prolongs blockade, decreases both heart rates and blood pressures and provides sedative effects.