Epinephrine in Digital Nerve Blocks: Medical Mistake or Evidence Based Practice?

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Joseph Anthony Andrews


Epinephrine, Ring Block, Digit, Necrosis, Ischemia, Local Anesthesia, Lidocaine


Ring blocks are an important asset for pain management during digit repair after injury. However, avoidance of epinephrine in digital ring blocks is a dogma perpetuated throughout medical school and post-graduate education. For most parts this dogma is rooted in historical inaccuracies obtained during the initial development of local anaesthetics in the late 19th and early 20th centuries. Analysis of 50 case reports of digital necrosis after ring blocks from the early 20th century reveals confounding factors such as procaine acidity, use of tourniquets, infection, and overuse of anesthesia as the likely cause of necrosis. Furthermore, analysis of over 200,000 cases of epinephrine ring blocks from the late 20th and early 21st centuries failed to identify a single case of digital necrosis. At the physiological level epinephrine causes vasoconstriction in the digits by binding to adrenergic receptors. However, necrosis does not occur due to the resilience of digits to short term ischemia. Consequently, use of epinephrine in ring blocks represents best practice because it decreases the time for anesthetic to work, prolongs the anesthetic effect, and produces hemostasis.