Despite common practice, epinephrine may speed up onset and prolong the effects of anesthesia
If you are like me you have been trained to not use epinephrine in digital nerve blocks. As a matter of fact I was taught NEVER to use epinephrine for regional nerve blocks involving the, “fingers, ears, toes, nose, and hose.” The fear is that the use of epinephrine will cause vasoconstriction and ultimately cause necrosis of tissue distally, due to the lack of collateral blood flow. This belief has been passed down from generation to generation of medical providers and quite honestly been accepted most likely because it makes physiological sense, but needs to be seriously challenged. Using epinephrine in digital nerve blocks may benefit patients by speeding up onset and helping prolong the effect of anesthesia.
What is the History of Epinephrine in Digital Nerve Blocks Causing Necrosis?
A review by Denkler K  in 2001 looked at all studies and major textbook chapters from the fields of anesthesia, orthopedics, and surgery from 1880 – 2000. It appears that cocaine was the first local anesthetic used documented in 1884 and the addition of epinephrine was not started until 1903. Upon review of the literature Denkler found that there were only 48 case reports of digital necrosis with the use of local anesthesia, but most were published before 1950. Also information about the concentration of epinephrine used, use of hot soaks (i.e burns), tourniquets, tight dressings, or preexisting medical conditions are not documented in most of these cases. Furthermore, upon review of the cases it looks like only 21 of the 48 cases used epinephrine with the local anesthesia and 17 of the 21 cases had unknown epinephrine concentrations. A review by Ilicki J et al in 2015  notes that since 1948 there have been no documented cases of digital necrosis directly attributable to epinephrine since the advent of commercial mixtures of lidocaine with epinephrine.
What do Tintinalli’s and Rosen’s say About the Safety of Epinephrine in Digital Nerve Blocks?
Tintinalli 7th ed Pg. 271: “The use of local anesthetic with epinephrine appears to be safe for use in end-arterial fields (fingers, toes, etc.) in selected healthy patients but probably should be avoided in suspected digital vascular injury; patients with vascular disease, such as Raynaud or Berger disease; or other conditions in which end-arterial vascular supply is problematic.” 
Rosen 8th ed Pg. 46: “Epinephrine-containing solutions have traditionally been avoided on digits, the penis, the ears, or the nose. It is suggested however, that dilute epinephrine can be used safely on digits and possibly these other areas as well. A comprehensive review of the use of epinephrine in digits concludes that it is safe when diluted to 1:200,000 or less but should not be used in patients with vascular disease.” 
What are the Benefits of Using Epinephrine in Digital Nerve Blocks?
There is evidence that the addition of epinephrine to digital nerve blocks does have benefit for patients. In 2003, Andrades et al randomized 43 patients into two groups 2% lidocaine vs 2% lidocaine with 1:100,000 epinephrine. At 10 minutes 84% vs 48% of patients could tolerate their procedure indicating quicker onset of anesthesia, total time of analgesia was 4.6 hrs vs 2.4 hrs, and there were zero cases of necrosis. Next, in 2012, Sonohata M et al studied 1.0% lidocaine vs 1.0% lidocaine with 1:100,000 dilution of epinephrine in 9 healthy volunteers for digital nerve blocks and found that no subjects showed any symptoms of ischemic injury, the mean time to anesthesia was approximately 2.8 minutes vs 4.0 minutes, and the mean duration of anesthesia was approximately 280 minutes vs 83 minutes. Finally, in 2013, Calder K et al anesthetized the ring fingers of 44 volunteers: One finger with bupivacaine alone and the other with bupivacaine with 1:200,000 epinephrine. The addition of epinephrine increased duration of anesthesia from 15 hours to 30 hours, but there was no mention of adverse events such as necrosis.
What’s The Most Recent Evidence About the Safety of Epinephrine in Digital Nerve Blocks?
On August 4, 2015, Ilicki et al published a large review in the Journal of Emergency Medicine including 39 studies looking at the safety of 1:100,000 – 1:200,000 epinephrine added to local anesthetics for digital nerve blocks. The results seem to refute the notion that epinephrine causes digital necrosis:
- There have been no cases of digit necrosis since 1948, attributable to epinephrine, since the advent of commercial mixtures of lidocaine and epinephrine have become available. Current epinephrine formulations available for local anesthesia use epinephrine in a 1:100,000 – 1:200,000 concentration.
- There were 2,797 digital nerve blocks reported in 23 studies with zero
complications due to the use of 1:100,000 –1:200,000 epinephrine.
- There were 186 cases of accidental injections of 1:1000 concentration epinephrine into digits reviewed. In one study 32 out of the 59 cases did not require any treatment and had zero cases of necrosis. In the other 77% of 127 patients did not require any treatment with 4 cases of ischemia requiring vasodilatory treatment with zero cases of necrosis.
- Most prospective studies have excluded high-risk populations; therefore use of epinephrine in digital nerve blocks is not well studied in patients with uncontrolled hypertension, pheochromocytoma, hyperthyroid states, poor digital circulation, peripheral vascular disease, smokers, and diabetes mellitus.
How Can you Reverse Digital Ischemia Once Epinephrine is Injected?
As an initial step you can try conservative management with warm water soaks and/or nitroglycerin paste. There are case reports supporting this treatment strategy, but there are also several reports of topical nitroglycerin not having any effect. There are also some older case reports from the 1960s that recommend Phentolamine for the reversal of 1:1000 epinephrine induced digital ischemia. Phentolamine is a reversible, non-selective alpha-adrenergic antagonist that causes vasodilation, which is why it is the best agent of choice in these cases. Nodwell et al  conducted a randomized trial of 22 subjects who all received 1.8mL of 2% lidocaine with 1:1000,000 epinephrine at three different sites of both hands. An hour later participants received 1mg of Phentolamine in one hand and 1mL of saline in the other and used color change in the hand as the time to effect. They found that in the Phentolamine injected hands average time for return of color was 85 minutes vs 319 minutes in the saline injected hands, an absolute difference of 234 minutes. In Aug 2014 McNeil C et al wrote up a case report and literature review finding that Phentolamine can be used at the puncture site or intra-arterially, but the key is small volumes to prevent worsening ischemia, and due to the short half-life, more than one injection may be necessary. Most importantly they state that there have been no adverse events reported from locally used Phentolamine. Phentolamine comes standard as 5mg in a 1mL vial. You can dilute this with 9mL of normal saline and using 1 – 2mg locally at the site of ischemia.
What is the Clinical Bottom Line?
- Use of 1:100,000 – 1:200,000 epinephrine in digital nerve blocks is safe in patients who have no evidence of digital vascular disease.
- Use of 1:100,000 – 1:200,000 epinephrine in digital nerve blocks is less well studied and probably safe in patients with poor peripheral circulation, but consider holding the epinephrine in these cases.
- If you need to reverse ischemia after the use of epinephrine start with warm water soaks and/or topical nitroglycerin paste, but if this does not work, consider using 1– 2 mg of Phentolamine at the site of injection.
- Andrades PR et al. Digital Blocks with or without Epinephrine. Plast Reconstr Surg 2003; 111: 1769 – 70.
- Calder K et al. Bupivacaine Digital Blocks: How Long is the Pain Relief and Temperature Elevation? Plast Reconstr Surg 2013; 131 (5): 1098 – 1104. PMID: 23629091
- Denkler K. A Comprehensive Review of Epinephrine in the Finger: to Do or Not to Do. Plast Reconstr Surg 2001; 108 (1): 114 – 24. PMID: 11420511
- Ilicki J. Safety of Epinephrine in Digital Nerve Blocks: A Literature Review. J Emerg Med 2015 [Epub ahead of print]. PMID: 26254284
- Marx JA. Rosen’s Emergency Medicine Concepts and Clinical Practice 8th ed. Elsevier Saunders 2014. Pg 46.
- McNeil C et al. Accidental Digital Epinephrine Injection: To Treat or Not to Treat? Can Fam Physician. 2014; 60(3): 726 – 728. PMCID: PMC4131962
- Newman DH. Truth, and Epinephrine, at Our Fingertips: Unveiling the Pseudoaxioms. Ann Emerg Med 2007; 50(4): 476 – 77. PMID: 17719691
- Nodwell T et al. How Long Does it Take Phentolamine to Reverse Adrenaline-Induced Vasoconstriction in the Finger and Hand? A Prospective, Randomized, Blinded Study: The Dalhousie Project Experimental Phase. Can J Plast Surg 2003; 11: 187 – 90. PMCID: PMC3760747
- Sonohata M et al. Subcutaneous Single Injection Digital Block with Epinephrine. Anesthesiol Res Pract. 2012; 2012. PCMID: PMC3137965
- Tintinalli JE. Tintinalli’s Emergency Medicine A comprehensive Study Guide 7th ed. McGraw-Hill Companies 2011. Pg 271.
- Nodwell et al. How long does it take Phentolamine to reverse adrenaline-induced vasoconstriction in the finger and hand? A prospective, randomized, blinded study: The Dalhousie project experimental phase. Can J Plast Surg 2003; 11 (4): 187 – 190. PMCID: PMC3760747