What are the guidelines for using interscalene blocks for postoperative pain management in shoulder procedures?

Guidelines for Interscalene Blocks in Shoulder Procedures

Continuous interscalene brachial plexus block is strongly recommended as the first-choice regional analgesic technique for postoperative pain management after shoulder procedures, as it provides superior pain control compared to single-shot blocks and systemic analgesia alone. 1

Regional Anesthetic Technique Recommendations

First-Line Approach

• Continuous interscalene block is preferred over single-shot interscalene block due to longer duration of analgesia and reduced rebound pain 1
• Continuous interscalene blocks provide lower pain scores and reduced opioid consumption on postoperative days 1,2, and 7 compared to single-shot blocks 1, 2
• Continuous interscalene blocks significantly reduce postoperative pain scores at 6h, 24h, and 72h as well as during physiotherapy compared to IV patient-controlled analgesia 1

Alternative Approaches

• If continuous interscalene block is not feasible, single-shot interscalene block should be used, but with awareness of its limited duration (6-8 hours) and potential for rebound pain at 24 hours 1
• If interscalene block is contraindicated, an axillary nerve block with or without suprascapular nerve block is recommended over no block or suprascapular nerve block alone 1, 2
• Supraclavicular block can be considered as an alternative to interscalene block as it provides non-inferior pain control while reducing respiratory complications 3

Optimizing Interscalene Block Efficacy

Adjuncts to Prolong Block Duration

• Intravenous dexamethasone is recommended to increase the analgesic duration of interscalene block and decrease supplemental analgesia requirements 1
• Perineural adjuncts such as buprenorphine, tramadol, or magnesium sulphate have limited procedure-specific evidence and are not routinely recommended 1
• Perineural glucocorticoids (betamethasone and dexamethasone) have limited evidence; intravenous dexamethasone is preferred over perineural administration 1

Multimodal Analgesia

• Regular administration of paracetamol and NSAIDs or COX-2 inhibitors is imperative to avoid significant pain after regional block resolution 1, 2
• Multimodal analgesia should be initiated pre-operatively or intra-operatively and continued into the postoperative period 1
• Arthroscopic approach is recommended over open procedures when possible as it reduces postoperative pain 1

Technical Considerations and Monitoring

Block Administration

• Ultrasound guidance is recommended for interscalene block placement to increase accuracy and reduce complications 2, 4
• For continuous interscalene block, ropivacaine 0.2-0.3% is effective, with higher concentrations (0.3%) potentially providing better opioid-sparing effects 1
• Continuous interscalene block with patient-controlled bolus capability may provide better analgesia than fixed-rate infusion alone 1

Potential Complications

• Monitor for temporary side effects including Horner's syndrome, phrenic nerve paralysis, and recurrent laryngeal nerve block 5
• Supraclavicular block has lower odds of respiratory dysfunction compared to interscalene block (OR = 0.08 for single-injection blocks; OR = 0.22 for continuous blocks) 3
• Interscalene block combined with general anesthesia reduces intraoperative opioid requirements and facilitates postoperative pain management 5, 6

Clinical Outcomes

Benefits Beyond Pain Control

• Effective interscalene blocks can reduce recovery room stay by approximately 25% compared to general anesthesia alone 5
• Interscalene blocks reduce postoperative opioid requirements, with up to 35% of patients requiring no additional analgesics in the first 24 hours 5, 6
• Combined approaches (interscalene block with continuous intralesional infusion) may provide extended pain relief up to 48 hours postoperatively 7

Patient Selection Considerations

• Calculate safe doses of local anesthetics to prevent systemic toxicity 2
• Consider patient comorbidities and anticoagulation status when selecting regional techniques 2
• Assess block success thoroughly before proceeding with surgery to minimize need for conversion to general anesthesia 2

By implementing these guidelines for interscalene blocks in shoulder procedures, clinicians can optimize postoperative pain management while minimizing opioid requirements and their associated side effects.