What is the recommended preparation for a supraclavicular block injection?

Preparation of Injections for Supraclavicular Block

For supraclavicular brachial plexus block, prepare ropivacaine 0.5% (5 mg/mL) at a volume of 30 mL (150 mg total dose) for single-injection technique, or use a 1:1 mixture of lidocaine 2% and bupivacaine 0.5% with epinephrine 1:200,000 at the same volume. 1, 2

Local Anesthetic Selection and Concentration

Primary Recommendation: Ropivacaine 0.5%

• Ropivacaine 5 mg/mL (0.5%) is the FDA-approved concentration for supraclavicular blocks, with doses up to 275 mg demonstrating safety and efficacy 1
• The 0.5% concentration provides success rates of 92% for supraclavicular blocks, superior to the 56-86% success rates seen with axillary approaches 1
• Median duration of sensory blockade ranges from 3.7 to 8.7 hours depending on nerve territory 1

Alternative: Mixed Local Anesthetic Solution

• A 1:1 mixture of bupivacaine 0.5% and lidocaine 2% with epinephrine 1:200,000 provides both rapid onset (from lidocaine) and prolonged duration (from bupivacaine) 2, 3
• This combination achieved 95% success rates for surgical anesthesia in ultrasound-guided supraclavicular blocks 2

Volume Calculation and Dosing

Standard Volume Approach

• Use 30 mL as the standard volume for single-injection supraclavicular block 2, 3, 4
• This volume provides effective anesthesia in 95% of patients when using ultrasound guidance 2
• The minimum effective volume in 50% of patients is 23 mL, with the ED95 calculated at 42 mL 3

Precision Dosing Based on Cross-Sectional Area

• For more precise dosing, calculate 0.189 mL/mm² of cross-sectional nerve area when using 0.5% ropivacaine 5
• This approach reduces the risk of local anesthetic systemic toxicity while maintaining efficacy 5
• Measure the brachial plexus cross-sectional area on ultrasound and multiply by 0.189 to determine the exact volume needed 5

Preparation Technique

Equipment Setup

• Use a 22-25 gauge needle for injection to balance adequate flow with minimal tissue trauma 6
• Prepare ultrasound equipment for real-time visualization of needle placement 2, 7
• Have neurostimulator available for confirmation of correct needle position 2

Injection Protocol

• Always use fractional (incremental) dosing rather than rapid bolus injection 1
• Aspirate before injection to avoid intravascular administration 8
• The smallest dose and concentration required to produce the desired result should be administered 1

Safety Considerations and Maximum Dosing

Dose Limits

• Maximum safe dose of ropivacaine for peripheral nerve blocks is 275 mg for single injection 1
• When using the mixed solution (lidocaine 2% + bupivacaine 0.5%), the 30 mL volume provides 300 mg lidocaine and 75 mg bupivacaine, both within safe limits 2

Monitoring for Toxicity

• Monitor for signs of local anesthetic systemic toxicity: circumoral numbness, facial tingling, slurred speech, metallic taste 8
• Watch for tinnitus or tongue numbness as early warning signs of intravascular injection 8
• Have lipid emulsion immediately available for treatment of systemic toxicity 1

Common Pitfalls to Avoid

• Do not use volumes less than 23 mL, as this increases the risk of incomplete block requiring supplementation or conversion to general anesthesia 3
• Avoid rapid injection of large volumes; always use incremental dosing to detect early signs of toxicity 1
• Do not proceed without ultrasound guidance, as this significantly reduces execution time (from 9.8 to 5.0 minutes) and improves block quality 2
• Never skip aspiration before injection, as accidental vascular puncture can occur despite ultrasound guidance 8, 7

Special Populations

• In debilitated patients or those with hepatic/renal dysfunction, reduce the dose and use the lower end of the volume range (23-30 mL) 1
• For patients with respiratory compromise, supraclavicular block is preferable to interscalene block as it avoids phrenic nerve involvement 9