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Abstract

Introduction: The success and complications associated with interscalene brachial plexus block (IBPB) anesthesia for shoulder surgery have been reviewed in recent retrospective reports with wide variability in results and differing conclusions. Numerous prior case reports have documented significant complications related to IBPB anesthesia. Those same reports generally conclude that the success of IBPB is less than optimal. Further, those reports conclude that IBPB should not be performed on patients who are heavily sedated or under general anesthesia because of the risk of undetectable intraneural injection of local anesthetic. This prospective study was undertaken to study the safety and efficacy of IBPB performed on patients after induction of general anesthesia. Methods: Following IRB approval, 500 consecutive consenting patients undergoing a variety of open and arthroscopic shoulder surgeries were enrolled in this study. For inclusion, the IBPB had to be performed by an anesthesiologist skilled and experienced in IBPB after the patient had been administered general anesthesia. Blocks were performed with an insulated needle, and a nerve stimulator was utilized to determine appropriate needle placement. Stimulation of the biceps brachia muscle, without stimulation of the phrenic nerve, with the current produced by the nerve stimulator set below 0.5 milliamps was required. Bupivicaine 0.5% with epinephrine 1:200,000 (40 ml) was instilled. Aspiration was performed after every 5 ml of injected fluid to ensure the absence of blood in the aspirate. Corticosteroid (Kenalog 25 mg) was randomly added to the anesthetic injection in some patients, while others received anesthetic without steroid. Adverse events were noted and followed, and the success and duration of each block was documented. Results: Mean time required for the performance of the blocks (positioning and preparation of the head/neck, needle placement, and instillation of meds) was 5.5 minutes. Mean current for nerve stimulation was 0.30 milliamps. The block was successful in 490 (98%) of the 500 cases. Overall mean block duration for all patients was 26 hours. Mean duration of analgesia for blocks performed without steroid was 20 hours. Mean duration for blocks performed with steroid was 28 hours. Immediate post-operative adverse side effects occurred in 54 patients (11%), including: Horner’s syndrome in 37 patients, mild subjective dyspnea due to phrenic nerve dysfunction in 7, severe subjective dyspnea in 3, and hoarseness due to recurrent laryngeal nerve dysfunction in 7. No patient suffered a pneumothorax. No treatment was required for the side effects of the IBPB. One block was aborted after instillation of 20 ml of Bupivicaine (without steroid) due to aspiration of blood during the routine intrablock aspiration check. That patient experienced 19 hours of post-injection analgesia. Nine patients noted persistent hypesthesia and/or paresthesia in the distal portion of the upper extremity after resolution of the analgesic effect of the IBPB. These symptoms resolved in less than one week in 4 patients. The remaining 5 patients had hypesthesis/paresthesia lasting longer than 2 weeks, but all noted spontaneous resolution between 2 weeks and 3 months post-IBPB. No patient had lasting sensory symptoms and no patient experienced persistent motor deficits. Conclusion: IBPB performed on patients under general anesthesia was found to be safe (no serious or permanent complications) and effective (98% success). It provided a satisfactory duration of effective analgesia (26 hours). Minor short-lasting adverse side effects occurred in 11% of patients, and temporary minor neurologic adverse events occurred in 2%. If noted, the author indicates something of value received. The codes are identified as follows: a, research or institutional support; b, miscellaneous funding; c, royalties; d, stock options; e, consultant or employee. *The Food and Drug Administration has not cleared the drug and/or medical device for the use described in this presentation (ie, the drug or medical device is being discussed for an “off-label” use). If noted, the author indicates something of value received. The codes are identified as follows: a, research or institutional support; b, miscellaneous funding; c, royalties; d, stock options; e, consultant or employee. *The Food and Drug Administration has not cleared the drug and/or medical device for the use described in this presentation (ie, the drug or medical device is being discussed for an “off-label” use).