When I first learned digital nerve blocks in the late 1990’s I was taught to mix Lidocaine and Bupivacaine 50/50 to provide faster onset (Lidocaine) and a longer duration of action (Bupivacaine). My use of two agents for digital nerve blocks was recently questioned by one of my colleagues.
Any time additional medications are drawn up into a syringe there is opportunity for error, and there is additional time added to the procedure. A review of the (limited) literature will try to answer the following questions:
- Does the addition of Lidocaine to Bupivacaine decrease the time to onset of anesthesia?
- Does the addition of Lidocaine to Bupivacaine decrease the pain of injection?
- Does the use of Lidocaine with Epinephrine prolong the duration of digital block long enough to obviate the need for Bupivacaine?
What evidence is available for Digital Nerve Blocks?
The available evidence to answer these questions is scant at best. A 2014 review  evaluated 6 articles that evaluated the use of Lidocaine, Lidocaine with Epinephrine, Lidocaine with Bupivacaine, Bupivacaine, and Ropivacaine. As Ropivacaine is not a commonly used emergency department drug this review will focus on the articles that assessed the pharmacodynamics of Lidocaine and Bupivacaine only.
Each study evaluated one or more of the following outcomes: Onset of anesthesia, duration of anesthesia, and pain of injection.
- Alhelali et al  compared 1% Lidocaine with epinephrine vs 0.5% Bupivacaine: 12 subjects, dorsal ‘ring’ approach, with bilateral middle finger blocks. Duration of analgesia was based on return of pain on pin prick.
- Thomson and Lalonde  compared 2% Lidocaine, 2% Lidocaine with Epinephrine, and Bupivacaine: 30 subjects, single volar injection, bilateral long fingers, and one small finger. Duration of anesthesia was based on return to normal sensation (this is typically longer than pin prick sensation.
- Valvalo and Leffler  compared 1% Lidocaine and 0.25% Bupivacaine vs 0.25% bupivacaine alone: 17 subjects, dorsal ‘ring’ approach, duration of anesthesia was based on return of pain on pin prick.
- Reichl and Quinton  compared 1% Lidocaine vs 0.5% bupivacaine: 24 (Lidocaine) and 29 (Bupivacaine) subjects, single volar injection. Duration of anesthesia was based on return of pain on pin prick.
Onset of Anesthesia
- Three studies assessed onset of anesthesia.
- Studies reported either mean, median, or both to describe onset of anesthesia. Ranges shown in parentheses.
Pain of Injection
- Two studies reported pain of injection.
- VAS scores are medians unless stated otherwise.
- There was a statistically and clinically significant (>13mm) difference in VAS pain scores when comparing Lidocaine with Epinephrine vs Bupivicaine containing injections.
Duration of Anesthesia
- Three studies assessed duration of anesthesia.
*There was heterogeneity in the way this was measured with Thomson and Lalonde using return to normal sensation, and the others using pain on pinprick as an end point. Pain on pin prick is considered a more objective, and comparable finding for studies to use.
The use of Bupivacaine with or without Lidocaine clearly provides a longer duration of anesthesia. The addition of Epinephrine to Lidocaine appears to significantly prolong the duration of anesthesia.
- The addition of Lidocaine to bupivacaine DOES NOT decrease the time to onset of anesthesia, and DOES NOT decrease the pain of injection. It adds some risk of medication error, and adds time to the procedure.
- Bupivicaine containing solutions, compared to Lidocaine with epinephrine INCREASE the pain of injection.
- Lidocaine with epinephrine provides a long enough duration of anesthesia to allow the completion of most emergency department procedures. Bupivacaine can be considered when post procedural analgesia is desired.
- In patient populations where pain of injection is a concern (pediatric, special needs adults) consider using Lidocaine with Epinephrine, rather than Bupavicaine.
- Alhelali M et al. Comparison of Bupivacaine and Lidocaine with Epinephrine for Digital Nerve Blocks. Emerg Med J 2009. PMID: 19386869
- Valvano MN et al. Comparison of Bupivacaine and Lidocaine/Bupivacaine for Local Anesthesia/Digital Nerve Block. Ann Emerg Med 1996. PMID: 8604868
- Reichl M et al. Comparison of 1% Lignocaine with 0.5% Bupivacaine in Digital Ring Blocks. J Hand Surg 1987. PMID: 3325593
- Thomson CJ et al. Randomized Double-Blind Comparison of Duration of Anesthesia Among Three Commonly used Agents in Digital Nerve block. Last Reconstr Surg 2006. PMID: 16874214
- Vinycomb TI et al. Comparison of Local Anesthetics for Digital Nerve Blocks: A Systematic Review. J Hand Surg am 2014. PMID: 24612831
- Michelle Lin at ALiEM: Sneak Peak “Trick of the Trade” – Digital Nerve Block
- Stella You at ALiEM: Trick of the Trade – Single Digital Block
Post Peer Reviewed By: Salim Rezaie, MD (Twitter: @srrezaie)
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