Why is epinephrine (adrenaline) avoided in digital ring blocks for procedures like partial nail avulsion?

Epinephrine IS Safe for Digital Ring Blocks

The historical teaching to avoid epinephrine in digital blocks is an outdated myth that has been definitively refuted by modern evidence—epinephrine with lidocaine is safe and recommended for digital procedures including partial nail avulsion. 1, 2

Why the Old Teaching Exists

The prohibition against epinephrine in digits stems from historical case reports from the early 1900s, but careful analysis reveals these cases involved:

• Older anesthetic compounds (cocaine, procaine, eukaine) rather than modern lidocaine 3, 4
• Manually diluted epinephrine with unknown and likely excessive concentrations (17 of 21 cases) 3
• Confounding factors including tight tourniquets, hot soaks, infection, and excessive injection volumes 3, 4
• No cases with commercial lidocaine-epinephrine preparations introduced in 1948 3

Current Evidence Supporting Epinephrine Use

The American Academy of Dermatology gives a Level A (strongest) recommendation for adding epinephrine to local anesthesia on digits, based on Level I and II evidence. 1

Safety Data

• Multiple systematic reviews and randomized controlled trials found no cases of digital necrosis with epinephrine use 1, 2
• At least 2,797 digital nerve blocks with epinephrine performed without complications 5
• Over 250,000 operations on hands, feet, fingers, and toes using lidocaine with epinephrine without necrosis 6
• No reported cases of gangrene attributable to commercial lidocaine-epinephrine mixtures 4

Clinical Benefits

Adding epinephrine to digital blocks provides significant advantages:

• Prolongs anesthesia duration by approximately 200% at concentrations of 1:50,000 to 1:200,000 1, 2
• Reduces need for tourniquet use which itself carries risk of ischemic injury 1, 2
• Provides hemostasis for improved surgical field visualization 2
• Faster onset of anesthesia 1
• Reduces peak blood levels of local anesthetic, decreasing systemic toxicity risk 1, 2

Recommended Technique

• Use commercial preparations of lidocaine with epinephrine at 1:100,000 or 1:200,000 concentration 1, 2
• Avoid manual dilution which led to historical complications 3, 4
• Buffer with sodium bicarbonate to reduce injection pain 1, 2
• Use lowest effective concentration for adequate anesthesia and vasoconstriction 1

When to Exercise Caution

While epinephrine is safe in healthy digits, consider avoiding it in:

• Active digital infection where tissue perfusion is already compromised 6
• Known severe peripheral vascular disease with poor digital circulation 6
• Raynaud's syndrome (one case report of fingertip gangrene exists) 6

However, even in patients with vascular comorbidities, two studies showed no complications with epinephrine use 5.

Bottom Line

For routine partial nail avulsion procedures, use lidocaine WITH epinephrine for digital ring blocks. 1, 2 The outdated prohibition causes unnecessary use of tourniquets (which carry their own ischemic risks), shorter anesthesia duration, and increased bleeding—all without any evidence-based safety benefit. 1, 3, 4