Letters

CJEM 2003;5(6):380-381

To the editor: While it is always reasonable to question dogma, I am not satisfied that local anesthetics with epinephrine are safe for use in fingers, toes, ears, the penis and the tip of the nose. I was not surprised when Dr. Katis stated¹ that he could not find any citations where digital blocks with epinephrine have caused a problem. In every modern textbook it is still considered a contraindicated application; therefore, it'd be a very brave physician who would report such a case.

Dr. Katis disregarded articles that reported complications from direct epinephrine injection into a digit. I suggest these articles would have been relevant because direct injection into other areas -- such as the arm or thigh -- generally does not cause complications. One such article,² published in CJEM, is of particular note: "Accidental injection of epinephrine by a child: a unique approach to treatment." Appended to this article was an Editor's Note (p. 36). It stated: "Although these authors specifically address the issue of epinephrine-injector injury, the therapy they describe is probably widely applicable to patients who undergo inadvertent digital injection of local anesthetic with epinephrine, which is a much more frequent ED occurrence."

We must decide in which situations the use of epinephrine would justify a potential increase in risk to the patient. In most cases involving digital repair in the ED it is completely unnecessary.

In the rare situation where epinephrine might be useful -- perhaps to prevent a trip to the operating room -- the patient must be informed of the risks because this treatment is outside the realm of standard care. The physician should be prepared to use rescue drugs such as phentolamine or terbutaline if the need arises.

Meite Moser, MD
Vancouver, BC

References

1. Katis PG. Epinephrine in digital blocks: refuting dogma. Can J Emerg Med 2003;5(4): 245-6.
2. Sellens C, Morrison L. Accidental injection of epinephrine by a child: a unique approach to treatment. Can J Emerg Med 1999;1(1):34-6.

[The author responds:]

Dr. Moser raises some important concerns. The studies to date suggest an absence of harm, and I agree that this does not equate with proof of safety. My contention is that the commonly espoused belief that epinephrine cannot be used with lidocaine in digital blocks is not supported by the medical literature and that, in fact, the weight of evidence argues in favour of its use.

Secondly, the article that Dr. Moser cites as evidence of complications from direct epinephrine injection into digits describes the accidental injection of an adult dose of epinephrine from an auto-injector syringe (used to treat allergic reactions) into the thumb of a child.² This scenario differs from the use of lidocaine-epinephrine formulations for local anesthesia. The typical adult epinephrine auto-injector device delivers 0.3 cc (0.3 mg) of 1:1000 epinephrine. In contrast, lidocaine and epinephrine formulations used for local anesthesia contain epinephrine in a concentration of 1:100000. If 1 cc of anesthetic is used in a digital block, the delivered epinephrine dose is 0.01 mg, and if 5 cc is used (as in the clinical trials), this is 0.05 mg of epinephrine. The epinephrine dose delivered by an auto-injector is, therefore 6-30 times higher. In fact, 30 cc of local anesthetic would need to be infiltrated into a finger to achieve the same dose as the adult auto-injector.

As to the contention that epinephrine is unnecessary in most cases involving digital repair in the ED, I would agree. The reason I use it in practice is because it makes my job easier. I rarely require a tourniquet, the blocks last longer, and I am always reassured by the preservation of capillary refill to the finger. In the unlikely event that ischemia occurs, Dr. Moser correctly mentions phentolamine or terbutaline as rescue drugs. To date, I have not had reason to use either.

Peter Katis, MD
University of Toronto
Toronto, Ont.

References

1. Katis PG. Epinephrine in digital blocks: refuting dogma. Can J Emerg Med 2003;5(4):245-6.
2. Sellens C, Morrison L. Accidental injection of epinephrine by a child: a unique approach to treatment. Can J Emerg Med 1999;1(1):34-6.