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Do epinephrine auto-injectors have an unsuitable needle length for young children?

Background

Epinephrine delivered by an auto-injector to the anterolateral aspect of the thigh is the standard of care for the emergency treatment of anaphylaxis. For most pediatric patients in Canada, the EpipenJr® is prescribed, which has a needle length of 12.7mm. The route of epinephrine administration affects its onset of action, and intramuscular delivery is recommended for rapid absorption. If epinephrine is injected subcutaneously, the absorption will be slower. Conversely, if it is injected into the bone, the absorption will be unpredictable. There are no published clinical studies assessing whether the needle length of the EpipenJr® is adequate to deliver epinephrine intramuscularly in pediatric patients at risk of anaphylaxis.

Methods

Consecutive pediatric patients under 15kg with confirmed food allergy who required prescriptions or refills of EpipenJr® at an allergist’s office were included in this study. An ultrasound of the anterolateral aspect of the mid thigh was performed under minimal (min) and maximal (max) pressure. Measurements of skin-to-muscle depth (STMD) and skin-to-bone depth (STBD) were completed. Baseline characteristics between two patient groups were compared: patients with STBDmax less than 12.7mm and patients with STBDmax greater than or equal to 12.7mm. Multivariable linear regression was performed including variables such as age, sex, BMI and race. The likelihood of the STBDmax of less than 12.7 mm was calculated for the weight groupings of <9kg,<11kg and <15kg.

Results

A total of 75 participants were included in this study. There were 21 patients (28%) that had STBDmax less than 12.7mm. Baseline characteristics differed significantly for height and weight of the participants between the two groups (p<0.05). Multivariable linear regression showed that age (p=0.0002) and BMI (p=0.00008) were significantly associated with STBDmax, following adjustment for sex and race. For patients under 9kg, 90% had STBDmax less than 12.7mm. For patients under 11kg, 53% had STBDmax less than 12.7mm.

Conclusions

Based on this study, there are a significant number of children under 15kg at risk of receiving an epinephrine auto-injector into the bone. Because of this risk, epinephrine auto-injectors should be prescribed with caution in this population.

Author information

Correspondence to Laura Kim.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Kim, L., Nevis, I.F., Tsai, G. et al. Do epinephrine auto-injectors have an unsuitable needle length for young children?. All Asth Clin Immun 10, A19 (2014) doi:10.1186/1710-1492-10-S1-A19

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Keywords

  • Public Health
  • Clinical Study
  • Young Child
  • Patient Group
  • Epinephrine