Longer needles recommended for epinephrine autoinjectors

(HealthDay)—Given the increasing epidemic of obesity, epinephrine autoinjectors (EAIs) for anaphylaxis require longer needles to ensure intramuscular injection, according to a study published online Feb. 13 in Allergy.

Jamie Johnstone, from New Cross Hospital in Wolverhampton, U.K., and colleagues examined the depth of subcutaneous tissue in a population of patients with anaphylaxis. The authors performed ultrasound and measurements of skin-to-muscle depth (STMD) at anterolateral thigh and anterior thigh in 28 patients (23 female; age range, 18 to 75 years) already prescribed EAIs for anaphylaxis.

The researchers found that using the recommended administration site of the anterolateral thigh, for 68 percent of patients the STMD was greater than the EAI needle length (15.02 mm). Female gender and body mass index over 30 kg/m² were key predictors for increased STMD.

"EAIs require longer needles to ensure intramuscular administration and ultrasound at point of prescription would aid needle length selection," the authors write.