Author: Jessica Bode, MD (EM Resident Physician, PGY-1, NUEM) // Edited by: Logan Weygandt, (EM Resident Physician, PGY-3, NUEM) // Expert Commentary: Patrick Lank, MD
Citation: [Peer-Reviewed, Web Publication] Bode J, Weygandt L (2016, May 31). The Best Agent For Digital Nerve Blocks [NUEM Blog. Expert Commentary by Lank P]. Retrieved from http://www.nuemblog.com/blog/digital-nerve-block/
Lidocaine vs Bupivacaine vs Both
A decade ago it was believed that the optimal anesthetic for digital blocks involved a mixture of one part lidocaine with one part bupivacaine, under the theory that by combining the two you could take advantage of the former’s quickness of onset and the latter’s duration of action. Still, this method has some very real disadvantages, namely that it is disruptive and takes time for a busy clinician to prepare, and it also introduces user error and uncertainty in terms of exactly which amounts of which anesthetic the patient is receiving. In light of the risks, do the theoretical advantages hold water?
One 1996 study compared this lidocaine/bupivacaine cocktail to bupivacaine alone and found that the median time to onset for both groups was almost identical - about 4 minutes, suggesting no advantage of the cocktail. Furthermore, when it comes to duration, bupivacaine again has the clear upper hand. A 2006 study from Thompson and Lalonde showed bupivacaine’s mean duration of action, defined as time from injection to time at which the patient could feel discernible pinpricks, was 24.9 hours compared 4.9 hours for lidocaine alone.
Based on these findings, the theoretical faster onset advantage of lidocaine is unrealized while the duration of action of bupivacaine is clearly superior. However, bupivacaine is not without drawbacks, and at least one study found that patients reported statistically significant increased pain levels with bupivacaine vs. other agents. If only there were a third option...
I can’t use epi...can I?
For years the mnemonic “fingers, nose, penis, toes” has helpfully summarized the areas thought to be particularly susceptible to ischemic injury, thus many clinicians have avoided using lidocaine with epinephrine when performing digital blocks. The addition of epinephrine to anesthetic solutions has two main hypothesized advantages - it causes local vasoconstriction that helps maintain a more bloodless field, and by the same mechanism it may also allow the anesthetic to concentrate in the desired areas for a longer period of time. Indeed, one recent study suggested that duration of action is twice as long when epinephrine is added to a lidocaine infiltration solution. Yet, what is the evidence for the ill-effects of epinephrine infiltration?
In 1949 a review of 50 case reports dating from 1889-1948 described examples of finger ischemia associated with procaine and cocaine injection with epinephrine. For over 50 years we have accepted this as dogma, despite several important flaws in the methods and conclusions of the study. Importantly, of the 50 cases included in the review, only 21 cases used epinephrine as an adjunct. Of those 21, 17 had unknown concentrations of epinephrine and all cases predated commercially available standardized preparations. These complications of epinephrine may be simply dose-dependent. In fact, it’s not clear that there is any demonstrable adverse effect at all.
Since then, large systematic literature reviews including studies of both low (1:100,00) and high (1:1,000) concentrations of epinephrine in lidocaine, have failed to find a single report of major ischemic complications attributable to the addition of epinephrine in digital blocks. In one recent multi-center prospective study, low-dose epinephrine was used for digital blocks with no evidence for necrosis or need for rescue agents. Furthermore, a 2004 study using Doppler flow studies on patients with digital blocks found that the vasoconstrictive effects of the injection resolve within 90 minutes, a duration unlikely to result in tissue ischemia or necrosis. Of note, these studies looked at patients with normal peripheral circulation and these results may not be generalizable to patients with peripheral arterial disease or other special populations with circulatory compromise such as Raynaud’s or scleroderma patients.
A caveat: while these data suggest that lidocaine with epinephrine for digital nerve blocks is low risk, you should practice within the guidelines of your institution. Local practice patterns often dictate what is considered “standard of care,” so any new practices should be discussed with hospital administration prior to implementation.
Take home points
- There are no data supporting the use of a lidocaine/bupivacaine cocktail as compared to lidocaine with epinephrine or bupivacaine alone
- Bupivacaine is a good choice, but limited data suggests that this agent causes more pain with administration than does lidocaine with epinephrine
- The dogma against epinephrine use in digital blocks is largely unfounded and outdated
- Use commercially available preparations with standardized concentrations
- Be wary of epinephrine in patients with peripheral artery disease or other causes of poor peripheral perfusion, and work within your hospital guidelines and local practice patterns
Dear Dr. Bode (aka, JBo),
It fills my heart with pride to see a first year resident take an interest in the evidence behind advantages and disadvantages of commonly used medications in the emergency department. For some uncertain reason, I too have thought about this issue quite a bit, and below are some of my reactions to both your post as well as to the question “with or without epi?” in general.
As I was reading your post, I was reminded of something one of the best emergency physicians I know, Dr. Steve Aks (@ERtox), says frequently. Paraphrased it is, “Never be the first to adopt a novel therapy… but definitely never be the last.” When all the textbooks said not to inject epinephrine into a digit, I clearly did not want to be the first one to say, “Ah, screw it! I do what I want. Give me ALL the epi!” But do I use it now that we have 10-15 years of published literature saying it is quite safe to use commercially prepared epinephrine in lidocaine for a digital block? Sure. Sometimes. And it can sort of help a little.
What I really like about your post is also your mature acknowledgment that there are other factors to using medication in the emergency department than just pathophysiology and pharmacology. You mention specifically “hospital guidelines” and “local practice patterns.” When you have a question like this one, there are other sources I encourage you to go to. Despite all the nonsense on them, I actually like to use package inserts to familiarize myself with the manufacturer’s reported side effects. As an example, for lidocaine with epinephrine, we are advised by the pharmaceutical company Hospira that we should use it “cautiously and in carefully circumscribed quantities in areas of the body supplied by end arteries…” This is only a precaution and not a contraindication or warning – essentially telling us if we are careful, using it in the right patients will probably be fine.
Finally, when I am wondering about issues related to medication use, I will frequently ask for assistance from our wonderfully amazing ED pharmacists. Something as simple as whether or not to use a medication may have many layers – is that medication restricted to a certain service or area of the hospital? Does the exact formulation you are requesting cost 10 times the alternative for little benefit? Is there a national shortage of the formulation you are requesting?
Thank you, Dr. Bode, for your excellent mini summary on medication decisions in digital blocks. I look forward to reading about what classic teaching you are going to battle against next.
Patrick M. Lank, MD, MS
Assistant Residency Program Director; Assistant Professor of Emergency Medicine; Attending Medical Toxicologist, Toxikon Consortium; Department of Emergency Medicine Northwestern University, Feinberg School of Medicine [Pubmed]
- Valvano MN, Leffler S. Comparison of bupivacaine and lidocaine/bupivacaine for local anesthesia/digital nerve block. Ann Emerg Med 1996; 27:490.
- Thomson CJ, Lalonde DH. Randomized double-blind comparison of duration of anesthesia among three commonly used agents in digital nerve block. Plast Reconstr Surg 2006; 118:429.
- Alhelail M, Al-Salamah M, Al-Mulhim M, Al-Hamid S. Comparison of bupivacaine and lidocaine with epinephrine for digital nerve blocks. Emerg Med J 2009; 26:347.
- Wilhelmi BJ, Blackwell SJ, Miller J, et al. Epinephrine in digital blocks: revisited. Ann Plast Surg 1998; 41:410.
- Thomson CJ, Lalonde DH, Denkler KA, Feicht AJ. A critical look at the evidence for and against elective epinephrine use in the finger. Plast Reconstr Surg 2007; 119:260.
- licki, Jonathan. 2015. Safety of Epinephrine in Digital Nerve Blocks: A Literature Review. The Journal of Emergency Medicine, no. 5.
- Lalonde et al. A Multicenter Prospective Study of 3,110 Consecutive Cases of Elective Epinephrine Use in the Fingers and Hand: The Dalhousie Project Clinical Phase
- Altinyazar HC, Ozdemir H, Koca R, et al. Epinephrine in digital block: color Doppler flow imaging. Dermatol Surg 2004; 30:508.