Auto-injector needle length may be inadequate to deliver epinephrine intramuscularly in women with confirmed food allergy

• Published in: Allergy, asthma, and clinical immunology asthma, and clinical immunology, 2014-07, Vol.10 (1), p.39-39, Article 39
• Main Authors: Tsai, Gina, Kim, Laura, Nevis, Immaculate Fp, Dominic, Arunmozhi, Potts, Ryan, Chiu, Jack, Kim, Harold L
• Format: Article
• Language: English
• Subjects: Analysis; Care and treatment; Dosage and administration; Epinephrine; First aid in illness and injury; Food allergy
• ISSN: 1710-1484; 1710-1492; 1710-1492
• DOI: 10.1186/1710-1492-10-39

Epinephrine auto-injectors are the standard first aid treatment for anaphylaxis. Intramuscular delivery into the anterolateral aspect of the thigh is recommended for optimal onset of action of epinephrine. The most frequently prescribed auto-injector in North America and Canada is the EpiPen(®), which has a needle length of 15.2 mm. Currently, it is unknown whether this needle length is adequate for intramuscular delivery of epinephrine in adult patients at risk of anaphylaxis. One hundred consecutive adult patients with confirmed food allergy requiring an epinephrine auto-injector were recruited. Skin to muscle depth (STMD) at the right mid-anterolateral thigh was measured using ultrasound under minimal (min) and maximum (max) pressure. The EpiPen(®) needle length was considered adequate if STMDmax was ≤15.2 mm. Baseline characteristics including age, gender, ethnicity, and body mass index (BMI) were compared in patients with STMDmax ≤15.2 mm vs. >15.2 mm. The EpiPen(®) needle length of 15.2 mm was inadequate for intramuscular delivery in 19 of the 100 enrolled patients (19%), all of whom were female; 28% of women had a STMDmax >15.2 mm. The mean STMDmax in the ≤15.2-mm and >15.2-mm groups were 9 ± 4 mm and 20 ± 4 mm, respectively (p = 0.0001). Linear regression analysis found BMI to be significantly associated with STMDmax after adjusting for age (p