Ultrasound-guided Axillary Brachial Plexus Block with 20 Milliliters Local Anesthetic Mixture Versus General Anesthesia for Upper Limb Trauma Surgery: an Observer-blinded, Prospective, Randomized, Controlled Trial

Objective: We performed a randomized, controlled trial comparing low-dose ultrasound-guided axillary block with general anesthesia evaluating anesthetic and perioperative analgesic outcomes.

Methods: Patients were randomized to either ultrasound-guided axillary block or general anesthesia. Ultrasound-guided axillary block was performed using a needle-out-of-plane approach. Up to 5 mL of local anesthetic injectate (equal parts 2% lidocaine with 1:200,000 epinephrine and 0.5% bupivacaine with 7.5 mg/mL clonidine) was injected after identifying the median, ulnar, radial, and musculocutaneous nerves. A maximum of 20 mL local anesthetic injectate was used. General anesthesia was standardized to include induction with fentanyl and propofol, maintenance with sevoflurane in an oxygen/nitrous oxide mixture. Pain scores were measured in the recovery room and at 2, 6, 24, 48 h, and 7 days. Ability to bypass the recovery room and time to achieve hospital discharge criteria were also assessed.

Results: All ultrasound-guided axillary block patients achieved satisfactory anesthesia. The ultrasound-guided axillary block group had lower visual analog scale pain scores in the recovery room (0.3 [1.3] vs 55.8 [36.5], P < 0.001), and visual rating scale pain scores at 2 h (0.3 [1.3] vs 45 [29.6], P < 0.001), and at 6 h (1.1 [2.7] vs 4 [2.8], P < 0.01). All ultrasound-guided axillary block patients bypassed the recovery room and attained earlier hospital discharge criteria (30 min vs 120 min 30/240 P < 0.0001 median [range]).

Conclusions: Ultrasound-guided axillary brachial plexus block with 20 mL local anesthetic mixture provided satisfactory anesthesia and superior analgesia after upper limb trauma surgery when compared with general anesthesia.