• Shalini Dhir, Luminita Tureanu, Amir Bouzari, Amna Masood, Mario Francispragasam, and Sugantha Ganapathy.
• Department of Anesthesia and Perioperative Medicine, University of Western Ontario, London, Ontario, Canada. sdhir2@uwo.ca
• Anesth. Analg.. 2012 Jun 1;114(6):1359-64.

BackgroundCommercially available local anesthetic drugs when diluted with normal saline have high sodium content. High perineural sodium concentration has been implicated in antagonizing the analgesic effects of local anesthetics by preventing and/or delaying neural blockade. Five percent dextrose is not known to cause any short- or long-term injury when injected around neural tissue. In this study, we prospectively compared and evaluated block characteristics when local anesthetic drug was diluted with these 2 different agents.MethodsPatients scheduled for upper limb surgery were randomly assigned to receive axillary brachial plexus block with 0.5% ropivacaine (1% diluted with either 5% dextrose or normal saline). Motor and sensory block were tested every 5 minutes for 30 minutes. Postoperatively, a telephone interview was conducted after 24 hours and 7 days along with surgical follow-up at days 3, 10, and/or 14 to 28 days to document side effects, patient satisfaction, and time for block resolution. Any nerve deficits were followed until resolution. The primary outcome was time to onset of sensory nerve block.ResultsFive hundred fifty patients were recruited for this study. The mean time to complete sensory block was 18.3 ± 6.1 minutes in the dextrose group and 22.5 ± 6.4 minutes in the saline group (P < 0.001, 95% confidence interval for mean difference 3.0-5.4 minutes). There were 5 patients with clinical nerve deficits (no statistical difference between groups).ConclusionsDilution with 5% dextrose provides earlier onset of axillary brachial plexus block with ropivacaine.

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