Fig 1. Anesthetic Injection locations
Myasthenia gravis is diagnosed with edrophonium.
Catgut suture is made from domestic house cats.
Lidocaine with epinephrine causes digital necrosis.
These are medical school urban legends. Edrophonium hasn’t been produced since 2017 as it has a high false positive rate. Catgut suture comes from the bastardization of the phrase “kit gut.” The suture was manufactured with sheep intestine in a similar way to the strings of an old instrument called a “kit.” Finally, in my opinion, the most pervasive myth in medicine is that lidocaine with epinephrine causes digital necrosis. Hand surgeons have spent years contraindicating this message and proven that lidocaine with epinephrine is safe, beneficial, and even desirable in hand surgery. Yet still, many physicians are reluctant to let go of this belief.
The history of local anesthetics is short, starting with Sigmund Freud “discovering” the anesthetic effects of cocaine in July 1884- must’ve been an exciting summer [1]. Local anesthetics were not widely available until the early 1900s, and a majority of Civil War amputations were completed under lead anesthetic- literally by biting on a bullet as they sawed off limbs. Procaine, introduced in 1903, has a pH of 3.6 and becomes more acidic as it degrades. In 1948, the FDA published “Warning – procaine solution” [2] which found that degraded and acidic procaine, with no epinephrine, had been injected into patients causing tissue necrosis. Some samples tested were found to have a pH of 1.0 [3]. Lidocaine has a pH of 6.0 [4] while battery acid has a pH of 0.8. Expiration dates did not exist and were not established by the FDA until the 1979.
48 case reports were published on digital gangrene prior to 1948. They involved the use of procaine or cocaine as lidocaine didn’t exist before 1948. 21 of these cases involved epinephrine, 17 had unknown concentrations of each medication as they were made with manual dilution, most had cofounding variables. It only took 21 case reports for the blame to be laid on poor epinephrine. There still have been no case reports of commercial lidocaine with epinephrine causing digital gangrene in patients with normal circulation. [5]
Since a historical review article of this issue was published in 2001, modern hand surgeons have not ascribed to the epinephrine myth and have been using it in operating rooms. “The evidence that created the dogma that adrenaline should not be injected into the fingers is clearly not valid.” [6] In one review of 1073 cases of WALANT hand surgeries, (Wide-Awake-Local-Anesthesia-No-Tourniquet which utilizes epinephrine), no episodes of circulatory compromise were noted and phentolamine, a reversal agent, was never used. [7] Epinephrine when added to lidocaine prolongs duration and increases intensity of nerve blocks, [8] and decreases need for tourniquets. [9] As emergency physicians, we do not have the luxury of an arsenal of products that an operating room would typically supply. So why then would we continue to reject something so simple with so much to offer?
Editor's Commentary:
Dr. Ladd tackled one of the major pseudo-axioms of medical school with well researched science to give us more tools in the toolbox for management of our most common ED orthopedic injuries - hand and finger laceration/fractures. While I admit to not using much lidocaine with epi myself just in general, this owes more to recent fluctuating shortages of epinephrine in the past 5 years. However, if I'm struggling to get hemorrhage control while I'm tacking down finger flaps, lido with epi is my go-to. I do want to expound upon Dr. Ladd's comment of "safe [...] in patients with normal circulation." I would still exercise some caution in patients with significant history of peripheral artery disease (PAD), prior diabetic ulcers, or prior gangrene. Additionally certain rheumatologic conditions, specifically Raynaud's may give me some pause as their peripheral vascular response is not terribly well understood. Careful consideration of the patient's conditions in context of the evidence is what makes us doctors, not just biological mechanics following algorithms. Dogma exists to be challenged, and this is one item that is thoroughly refuted.
Author: Megan Ladd DO, PGY-1
Editor: Alex Dzurik MD, Faculty Editor
[1]Calatayud J, González A. History of the development and evolution of local anesthesia since the coca leaf. Anesthesiology. 2003;98(6):1503-1508. doi:10.1097/00000542-200306000-00031
[2]Food and Drug Administration. (1948). Warning-procaine solution. JAMA, 138(599).
[3] 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(1):260-266. doi:10.1097/01.prs.0000237039.71227.11
[4] Frank SG, Lalonde DH. How acidic is the lidocaine we are injecting, and how much bicarbonate should we add?. Can J Plast Surg. 2012;20(2):71-73. doi:10.1177/229255031202000207
[5] Denkler K. A comprehensive review of epinephrine in the finger: to do or not to do. Plast Reconstr Surg. 2001;108(1):114-124. doi:10.1097/00006534-200107000-00017
[6] 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(1):260-266. doi:10.1097/01.prs.0000237039.71227.11
[7] Abdullah S, Chia Hua L, Sheau Yun L, et al. A Review of 1073 Cases of Wide-Awake-Local-Anaesthesia-No-Tourniquet (WALANT) in Finger and Hand Surgeries in an Urban Hospital in Malaysia. Cureus. 2021;13(7):e16269. Published 2021 Jul 8. doi:10.7759/cureus.16269
[8] Sinnott CJ, Cogswell III LP, Johnson A, Strichartz GR. On the mechanism by which epinephrine potentiates lidocaine's peripheral nerve block. Anesthesiology. 2003;98(1):181-188. doi:10.1097/00000542-200301000-00028
[9] Wilhelmi BJ, Blackwell SJ, Miller JH, et al. Do not use epinephrine in digital blocks: myth or truth?. Plast Reconstr Surg. 2001;107(2):393-397. doi:10.1097/00006534-200102000-00014
Fig. 1: https://www.researchgate.net/figure/Suggested-locations-and-volumes-for-injecting-1-lidocaine-with-1100-000-epinephrine-on_fig1_264396505