What are the considerations and potential risks for using a supraclavicular brachial plexus block in patients undergoing humerus surgery?

Supraclavicular Brachial Plexus Block for Humerus Surgery: Evidence and Considerations

Primary Safety Concern

Supraclavicular brachial plexus blocks carry a higher frequency of serious adverse reactions regardless of the local anesthetic used, and should be approached with heightened caution for humerus surgery. 1

Key Risk Stratification

Hemorrhagic Complications

• Supraclavicular blocks are classified as deep/non-compressible blocks with elevated bleeding risk 2
• Only 26 published reports of significant hemorrhagic complications exist for all peripheral nerve blocks, with half occurring in anticoagulated patients and half in those with normal coagulation 2
• Patient harm from supraclavicular blocks specifically includes:
  • Airway obstruction from hematoma compression 2
  • Occlusion of major blood vessels 2
  • Tissue ischemia 2

Absolute Contraindications for Supraclavicular Blocks

• Active P2Y12 inhibitor therapy (clopidogrel, prasugrel, ticagrelor) without 5-7 day discontinuation 3
• Therapeutic anticoagulation unless appropriately reversed 3
• Uncorrectable coagulopathy or bleeding disorders 3
• Patient refusal 3
• Active infection at injection site 3

Relative Contraindications Requiring Risk-Benefit Analysis

• Aspirin monotherapy may proceed only if benefit/risk ratio is favorable 3
• Dual antiplatelet therapy requires careful assessment 3

Local Anesthetic Toxicity Risk

Ropivacaine plasma concentrations may approach the threshold for CNS toxicity after 300 mg administration for brachial plexus block 1

• The dose must be adjusted according to administration site and patient status 1
• Major nerve blocks involve large volumes in highly vascularized areas with increased risk of intravascular injection 1
• Recommended dosing for brachial plexus block: 175-250 mg (35-50 mL of 0.5%) or 75-300 mg (10-40 mL of 0.75%) 1

Mandatory Safety Requirements

• Ultrasound guidance is mandatory for all nerve blocks to reduce local anesthetic systemic toxicity risk 3
• Experienced operator performing the technique is required 3
• Calculated safe dose based on patient weight is necessary 3
• Immediate resuscitation equipment availability is required 3
• For supraclavicular blocks specifically, nerve stimulation with minimal threshold of 0.9 mA is recommended 4

Efficacy Considerations for Humerus Surgery

Anatomical Coverage

• Supraclavicular blocks provide more complete anesthesia of the brachial plexus compared to other approaches 4
• For proximal humeral surgery, interscalene approaches are traditionally preferred, though supraclavicular blocks can provide adequate coverage 4
• Supraclavicular blocks with multiinjection intracluster technique exhibit significantly reduced total anesthesia-related time and higher success rates (compared to axillary approaches) 5

Performance Characteristics

• Success rate with 20 mL ropivacaine 0.75% using ultrasound-guided multiinjection technique is significantly higher than axillary approach 5
• Performance time is similar across supraclavicular, infraclavicular, and axillary approaches when using low-volume (20 mL) techniques 5
• No early adverse effects occurred in comparative studies using ultrasound guidance with restricted volumes 5

Ultrasound Guidance Impact on Safety

Ultrasound-guided regional anesthesia, when employed by experienced clinicians, may decrease the incidence of vascular puncture and make supraclavicular blocks safer in the presence of altered coagulation 2

Positioning-Related Nerve Injury Prevention

• Limit arm abduction to ≤90° in supine patients to prevent brachial plexus injury 2, 6
• Use padded armboards to decrease upper extremity neuropathy risk 2
• Periodically assess upper extremity position during procedures 2
• Avoid shoulder braces in steep head-down positioning 2

Preoperative Risk Assessment

Screen for high-risk features that increase perioperative neuropathy risk 2, 6:

• Body habitus
• Preexisting neurologic symptoms
• Diabetes mellitus
• Peripheral vascular disease
• Alcohol dependency
• Arthritis

Alternative Approaches for Humerus Surgery

For ambulatory surgical procedures, axillary or mid-humeral blocks remain the most logical approaches for surgery at and below the elbow, while reserving supraclavicular approaches for surgery from the proximal humerus to above the elbow 7

• Infraclavicular blocks may result in decreased performance time and block-related pain with similar efficacy 4
• Humeral canal blocks at the junction of proximal and middle third of the arm provide efficient and safe anesthesia with 82.1% success rate for forearm and hand surgery 8

Postoperative Monitoring

• Examine the patient in PACU for early recognition of peripheral neuropathy 2
• Document specific positioning actions during patient care 2
• Maintain high index of suspicion for delayed complications including pneumothorax in ambulatory settings 7