Accidental injection of epinephrine from an autoinjector: Invasive treatment not always required.

ABSTRACT

Background. Individual case reports of accidental injection with epinephrine appear in the literature and seem to represent the worst case scenarios. We present a case series of 28 exposures to epinephrine via autoinjector.

Method. All accidental parenteral injections of epinephrine by autoinjector reported to two regional poison information centers over a 2-year period were included.

Results. Injection sites included digits (23 cases), palm (4 cases), and thigh (1 case). Symptoms included swelling, pallor, pain, and erythema. Four patients reported no effect, and 9 required no treatment. Ten patients obtained relief with warm soaks, 1 patient had massage only, and 2 patients were lost to follow-up. Fourteen were examined in the emergency department, and 14 were treated at home.

Conclusion. Although some injection injuries must be treated in an emergency facility, many can be treated at home. Immediate referral to a health care facility is not needed in all cases and at times is unwarranted.

EPINEPHRINE AUTOINJECTOR DEVICES have been available since 1980. (1) This prescription spring-loaded device allows patients who have acute allergic reactions to self-inject epinephrine immediately Accidental injection, often involving a digit, may be associated with severe morbidity. Numerous case reports describing these injuries can be found in the medical literature.(1-3) These reports represent the worst scenarios and give the impression that all such exposures must be treated in an emergency medical facility, often using invasive procedures. Using data from two poison control centers, we retrospectively reviewed accidental parenteral injection of epinephrine by autoinjectors.

METHODS

All unintentional parenteral epinephrine autoinjector exposures reported to two American Association of Poison Control Centers (AAPCC) Regional Poison Information Centers (the Maryland Poison Center and the Pittsburgh Poison Center) over a 2-year period were included. The cases were identified utilizing Dotlab, an online data entry system that complies with all criteria required by the AAPCC Toxic Exposure Surveillance System. The databases were queried by product-specific codes as well as Poisindex numeric and generic codes, which identified the exposures. The cases were then reviewed, and the data were tabulated.

RESULTS

Twenty-eight unintentional parenteral exposures were identified. Four exposures resulted from injection with the Epipen Jr. device and 24 with the Epipen autoinjector. Twelve male and 16 female subjects ranged in age from 4 to 70 years (mean, 14 years [+ or -] SD 15.71 years). Twentytwo of the accidental injections occurred in the home, 4 in the workplace, and 2 in school.

Of the four Epipen Jr. exposures, the injection sites were digits in 3 cases and the palm in 1 case. Two of these patients had no symptoms. One 7-year-old boy with a digital injection had pallor in the finger and was treated with warm soaks at home. The patient was asymptomatic 3 hours after exposure. The 5-year-old child injected in the palm had erythema and swelling at the site. He was referred to an emergency department for observation and cardiac monitoring. This patient was asymptomatic 4 hours after exposure and was discharged. All 28 exposures were reported to the poison center within 10 minutes of the incident.

Of the 14 patients seen in an emergency department, 3 received transdermal nitroglycerin and had relief within 3 hours after exposure. A 27-year-old patient with a pale, cold digit had local infiltration with phentolamine and was asymptomatic 1 hour after the epinephrine injection. A 13-year-old patient with symptoms of swelling and pain had nitroglycerin applied, followed by local infiltration of terbutaline, and was asymptomatic 3 hours after exposure. It was unclear whether the terbutaline was used because the nitroglycerin application was unsuccessful. A 24-year-old patient with numbness and blanching at the site of digital in had nitroglycerin applied topically, followed by parenteral phentolamine. The patient reported no relief of symptoms with the nitroglycerin paste alone but was asymptomatic 3 hours after the epinephrine injection. Six patients had relief with warm compresses or warm water soaks. One of these six had palmar injection.

Home treatment included warm soaks, warm compresses, and massage. Eight patients had digital injections; two had palmar injections. Of those with palmar injection, one was treated with warm soaks and the other, an inebriated man, refused treatment despite complaining of tachycardia. All were asymptomatic within 3 hours of the exposure.

A 31-year-old pregnant woman at 20 weeks' gestation was injected accidentally in the thigh by her son. She had abdominal pain and nausea and was admitted to obstetrics for observation. At 3 hours after exposure, contractions decreased, and no labor progression was noted.

DISCUSSION

Epinephrine autoinjector pens are available in two strengths, 0.5 mg/mL (1:2000 of epinephrine that delivers 0.15 mg) and 1 mg/mL (1:1000 of epinephrine that delivers 0.3 mg).1 Indications for use include immediate self- administration for anaphylactic shock in allergic emergencies.

Epinephrine is a direct-acting sympathomimetic agent with effects on both [alpha]-adrenergic and [beta]-adrenergic receptors. Stimulation of [alpha]-receptors after parenteral administration results in peripheral cutaneous vasoconstriction, increased cardiac output, and increased systolic blood pressure. [beta]-Adrenergic effects include increased heart rate and skeletal muscle blood How, with a resultant drop in diastolic blood pressure. Epinephrine also causes bronchodilation, which in combination with its other effects makes it extremely beneficial in the management of an allergic response. (2) The onset of action when administered subcutaneously is slowed by local vasoconstriction but is more rapid when injected intramuscularly. (5) The adverse effects of unintentional injection with epinephrine are due to the [alpha]-adrenergic effects, especially when the injection site is localized, such as in a digit. This can produce severe local vasospasm, resulting in tissue necrosis. (2) Symptoms may include pain, blanching, decreased surface temperature, pallor, and edema. (3)

The main goal of treatment is to decrease the vasospasm of the affected area, allowing adequate blood flow to alleviate the patient's discomfort and avoid progressive necrotic damage. Current treatment recommendations include digital blocks with 1 % lidocaine, local injections of phentolamine, or a combination of phentolamine and lidocaine. (26]

A review of the medical literature revealed numerous individual case reports describing symptomatic accidental digital injections usually treated with local phentolamine infiltration. (1-3) While effective, this procedure is not without risk. When a digit is involved as the injection site, limited space is available for additional fluid volume. (3) A compartment syndrome is possible, resulting in pressure-induced exacerbation of ischemia. (2) Phentolamine can also cause hypotension and tachycardia when administered parenterally. (1)

In this case series of 28 patients, only 2 required phentolamine injections. One patient was treated with terbutaline. In 2 patients, treatment was unknown. The majority of exposures (86%) necessitated minimal, if any therapy. Vasodilation was accomplished by application of heat, physical stimulation, and application of transdermal nitroglycerin. Both groups of patients, those treated in an emergency facility and those treated at home, are comparable with regard to time between exposure and treatment, injection site, and time to relief.

CONCLUSION

Despite published reports of cases treated with invasive procedures (ie, phentolamine injections), not all injection injuries need emergency department treatment. Initial therapy consisting of warm compresses or submerging the affected part in warm water may be initiated immediately after the exposure. Appropriate follow-up should be conducted to determine the extent of relief and whether an emergency referral is justified. A trial of topical nitroglycerin may be considered, though its efficacy is controversial.

References

(1.) McGovern SJ: Treatment of accidental digital injection of adrenaline from an auto-injector device. J Accid Emerg Med 1997; 14:379-380

(2.) McCauley WA, Gerace RV, Scilley C: Treatment of accidental digital injection of epinephrine. Ann Emerg Med 1991; 20:665-668

(3.) Maguire W, Reisdorff EJ, Smith D, et al: Epinephrine-induced vasospasm reversed by phentolamine digital block. Am J Emerg Med 1990; 8:46-47

(4.) Billups NE, Billups SM: American Drug Index Facts and Comparisons. St. Louis, Wolters Kluwer, 1999

(5.) Hardman JG, Limbird LE: Catecholamines, sympathomimetic drugs, and adrenergic receptor antagonists. Goodman and Gilman 's The Pharmacological Basis of Therapeutics. NewYork, McGraw-Hill Ca, 1996, pp 199-248

(6.) Ellenhorn MJ, Schonwald 5, Ordog G, et al: The home. Ellenhorn's Medical Toxicology. Philadelphia, Williams & Wilkins Co, 1997, pp 974-976

RELATED ARTICLE: KEY POINTS

* Accidental injections with epinephrine autoinjectors occur frequently.

* The most severe cases are reported in the medical literature implying severe morbidity.

* Often these injuries can be treated onsite in a nonhealth care facility with excellent results.

From the Pittsburgh Poison Center, Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pa; and the Maryland Poison Center, University of Maryland at Baltimore.

Reprint requests to Rita Mrvos, BSN, Pittsburgh Poison Center, Children's Hospital of Pittsburgh, 3705 Fifth Ave. Pittsburgh, PA 15213.