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

Abstract

BackgroundEpinephrine 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.MethodsOne 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.ResultsThe 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 < 0.001).ConclusionsThe needle length of the epinephrine auto-injectors may not be adequate for intramuscular delivery of epinephrine in a large proportion of women with food allergy; this may impact morbidity and mortality from anaphylaxis in this patient population.

Epinephrine in anaphylaxis

“…In addition, needle lengths vary from 1.17 to 2.5 cm on the basis of different manufacturers (Table 1) [ [16][17][18]. There is no explanation on how the needle length of approximately 1.43 cm was chosen.…”

Needle length for epinephrine prefilled syringes in children and adolescents: Is it one inch?

“…[11][12][13][14][15][16][17][18] Studies in adult have shown the inadequacy of the epinephrine auto-injector needle length especially in women.…”

À qui prescrire un dispositif auto-injectable d’adrénaline ? Position des groupes de travail « Anaphylaxie », « Allergie alimentaire », « Insectes piqueurs » sous l’égide de la Société française d’allergologie

“…Les longueurs des aiguilles varient selon le dispositif : 7,5 mm pour Anapen ® 0,15 et 0,30 mg, 13 mm pour Jext ® 0,15 mg, 15 mm pour Jext ® 0,30 mg, 12,5 mm pour EpiPen ® 0,15 mg et 15,5 mm pour EpiPen ® 0,3 mg (informations fournies par le fabricant). Cependant, les longueurs des aiguilles précisées dans les études sont différentes [43][44][45][46][47]. Plusieurs études montrent que l'injection pourrait ne pas être efficace en raison d'une longueur d'aiguille insuffisante pour une injection intramusculaire du fait de l'épaisseur du pannicule adipeux, notamment chez les femmes obèses, même en respectant les posologies [43][44][45][46].…”