LOS ANGELES — Infants weighing between 7.5 kg-15 kg were at increased risk of overpenetration from needles in commercially available pediatric epinephrine autoinjectors, according to study findings presented at the American Academy of Allergy, Asthma & Immunology Annual Meeting.
“Epinephrine autoinjectors are the first line of treatment for anaphylaxis. It’s most effective when delivered intramuscularly but too much force or imprecise needle length can cause intraosseous injection, causing the needle to come into the bone marrow,” researcher Harold L. Kim, MD, of the Western University Schulich School of Medicine and Dentistry in London, Ontario, said in a press release. “The standard needle length for pediatric patients is 12.7 mm, however, the ideal needle length for infants and toddlers weighing 7.5 to 15 kg is unknown.”
Harold L. Kim
To determine the optimal needle length for this population, Kim and colleagues enrolled infants and toddlers (n=53) from two North American ambulatory allergy clinics who underwent baseline and compression ultrasound of the anterolateral thigh.
Researchers used an ultrasound modified transducer that simulated the impression and maximum activation force an epinephrine autoinjector. These ultrasound images were then examined offline – blinded to clinical data – for skin-to-bone and skin-to-muscle distance in short axis approach.
According to results of the ultrasound study of patients weighing 7.5-15 kg, the average skin-to-bone distance was 22.8 mm, while the skin-to-muscle distance was only 8.2 mm.
“With ten pounds of compression, the average skin-to-bone distance in the transverse plain was 13.3 mm,” Kim told Healio.com/Allergy. “With a standard autoinjector needle length of 12.7 mm, this means that 43% of the children in our study were at risk of having the needle actually strike the bone, which is significant.”
During a press conference, Kim cautioned that if the needle struck the periosteum and the epinephrine entered the intraosseous space, the effect would be similar to giving epinephrine intravenously; this represents a paramount concern as the epinephrine in autoinjectors is more concentrated than would be given in an intravenous dose, and is delivered much more rapidly.
“Epinephrine autoinjectors are still the mainstay of treatment and they should be prescribed when indicated,” Kim told Healio.com/Allergy. “However, with studies like ours coming out, I think we have to be aware that these autoinjectors are not designed for everyone and some modifications may have to be made in the way they are given or in the directions we give to patients due to these potential issues.”– by Bob Stott
Kim H, et al. Abstract 918. Presented at: the American Academy of Allergy, Asthma & Immunology Annual Meeting; March 4-7, 2016; Los Angeles.
Disclosure: Dr. Kim reported funding from Sanofi.