What is the duration of a supraclavicular block with bupivacaine?

Duration of Supraclavicular Block with Bupivacaine

A supraclavicular brachial plexus block with plain 0.5% bupivacaine typically provides 3-4 hours of analgesia, though this can be extended to 6-7 hours with clonidine or dexmedetomidine as adjuvants.

Plain Bupivacaine Duration

The baseline duration of analgesia with bupivacaine alone in supraclavicular blocks is relatively limited:

• Plain 0.5% bupivacaine provides approximately 194 minutes (3.2 hours) of analgesia when used for supraclavicular brachial plexus block 1
• A similar study using 0.25% bupivacaine demonstrated approximately 728 minutes (12 hours) of analgesia, though this longer duration reflects the larger volume (40-50 ml) used 2
• The concentration and volume both influence duration, with 0.325% bupivacaine (30 ml) providing intermediate duration 3

Extended Duration with Adjuvants

Adding alpha-2 agonists dramatically prolongs the analgesic duration:

Clonidine as Adjuvant

• Adding 30 mcg of clonidine to 0.5% bupivacaine extends analgesia duration to 415 minutes (6.9 hours), more than doubling the plain bupivacaine duration 1
• Higher doses of clonidine (150 mcg) with 0.25% bupivacaine can provide up to 994 minutes (16.6 hours) of analgesia 2
• The main side effect is increased sedation, though this is generally well-tolerated without clinically significant hemodynamic changes at lower doses 1

Dexmedetomidine as Adjuvant

• Dexmedetomidine 100 mcg (1 mcg/kg) added to bupivacaine significantly prolongs both sensory and motor block duration 3
• This adjuvant also shortens the onset time of the block 3
• Dexmedetomidine may cause bradycardia and hypotension, requiring closer hemodynamic monitoring 3
• When dexmedetomidine is used, the bupivacaine dose can potentially be reduced by 50% while maintaining similar block characteristics 4

Clinical Considerations

Important factors affecting block duration:

• Concentration matters: Higher concentrations (0.5% vs 0.25%) provide more dense blocks but not necessarily longer duration when volume is adjusted 5
• Volume is critical: Larger volumes (40-50 ml) provide longer duration than smaller volumes (20-30 ml), even at lower concentrations 2
• Mixing with lidocaine does not affect duration: Combining 2% lidocaine with 0.5% bupivacaine (either sequentially or mixed) does not change the onset or duration compared to using them separately 5

Practical Recommendations

For routine supraclavicular blocks:

• Expect 3-4 hours of analgesia with plain 0.5% bupivacaine (20-30 ml volume) 1
• Plan for supplemental analgesia starting around 3 hours postoperatively 1

For extended postoperative analgesia:

• Add clonidine 30-150 mcg to extend duration to 7-16 hours, accepting mild sedation as a trade-off 1, 2
• Consider dexmedetomidine 1 mcg/kg as an alternative, but monitor for bradycardia and hypotension 3

Common pitfall: Do not rely on mixing bupivacaine with lidocaine to extend duration—this combination does not prolong the block beyond what bupivacaine alone provides 5