Continuous parascalene block for shoulder surgery

OBJECTIVE: To evaluate the efficacy and incidence of side effects of parascalene brachial plexus block for shoulder surgery and for postoperative analgesia. PATIENTS AND METHODS: This prospective descriptive study enrolled 186 patients scheduled for conventional (open) and arthroscopic shoulder operations. The parascalene approach to the brachial plexus was used, with an 18-G x 4.5 cm cannula (30 degrees bevel), applying the technique of detecting perforation of the prevertebral fascia. Mepivacaine 1.5% was administered for anesthesia, beginning with a test dose of 5 ml followed by doses of 25 ml. Bupivacaine 0.125% with 1/400,000 adrenaline was given for postoperative analgesia. Two groups were established according to type of surgery. In group A were patients undergoing open surgery and those with articular stiffness undergoing arthroscopic surgery; analgesics were delivered in continuous perfusion of 5 to 8 ml/h. Group B patients, who underwent arthroscopic surgery, received the analgesic in boluses of 10 to 14 ml every 4 to 6 hours. We assessed perception of perforation of the fascia, provocation of paresthesia, number of puncture attempts, anesthetic efficacy, postsurgical analgesia (visual analogue scale from 0 to 10) and complications. RESULTS: Blockade was effective for 155 of the 186 patients (83.33%). In 118 (63.44%) the perception of perforation of the prevertebral fascia was ostensible, in 52 (27.95%) it was slight and in 16 (8.6%) it was undetectable. Paresthesia was triggered by the cannula in 18 cases (9.13%) and by the test dose in 181 cases (97.31%). The mean number of puncture attempts was 1.2 +/- 0.09 per patient. During the early postoperative period analgesia was adequate for 92 (84.40%) of the 109 patients in group A. In group B, 45 patients (97.82%) required 1 to 2 analgesic doses (mean 1.4 +/- 2 doses) and one patient (2.17%) needed 6 doses within the first 24 hours. Catheters remained inserted as long as 36 hours to 10 days (mean 3.5 days) in group A. In group B they had been removed by 24 hours. Complications were transitory and slight. No cases of pneumothorax, no intra- or epidural anesthesia was required and no instances of vascular puncture occurred. CONCLUSIONS: The parascalene approach is easy to use and entails few risks while providing excellent anesthetic conditions for open and arthroscopic shoulder operations. It is useful for ambulatory analgesia to facilitate early rehabilitation after surgery.