Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate, Inc. and/or its affiliates. All Rights Reserved.

Medline ® Abstracts for References 41,42

of 'Anaphylaxis: Emergency treatment'

Adequacy of the epinephrine autoinjector needle length in delivering epinephrine to the intramuscular tissues.
Song TT, Nelson MR, Chang JH, Engler RJ, Chowdhury BA
Ann Allergy Asthma Immunol. 2005;94(5):539.
BACKGROUND: Epinephrine injected by an autoinjector in the anterolateral aspect of the thigh is the standard of care in the emergency self-treatment of anaphylaxis. In the United States, the autoinjector EpiPen is widely used for the self-treatment of anaphylaxis.
OBJECTIVE: To investigate whether EpiPen autoinjector, with a needle length of 1.43 cm, is sufficient for intramuscular delivery of epinephrine in men and women.
METHODS: The distance from skin to muscle in the anterolateral aspect of the thigh was measured in 50 men and 50 women who had undergone computed tomography of the thighs for other medical reasons. For each individual, body mass index (BMI; a measure of weight in kilograms divided by the square of height in meters) was also calculated, and the individuals were classified as underweight (BMI,<18.5), normal (BMI, 18.5-24.9), overweight (BMI, 25.0-29.9), and obese (BMI,>or = 30.0) using standard definition.
RESULTS: In the study participants the mean +/- SD distance from skin to muscle was 0.66 +/- 0.47 cm for men and 1.48 +/- 0.72 cm for women (P<.001). One man (obese at a BMI of 42.2) and 21 women (11 obese with a mean BMI of 35.2, 6 overweight with a mean BMI of 30.1, and 4 normal with a mean BMI of 24.5) had a greater distance from skin to muscle than the EpiPen needle length of 1.43 cm.
CONCLUSION: The distance from skin to muscle for the anterolateral aspect of the thigh is higher in women compared with men. This difference suggests that EpiPen may not deliver epinephrine to the intramuscular tissue in many women.
Department of Allergy and Immunology, Walter Reed Army Medical Center, Washington, DC 20307-5001, USA.
Epinephrine auto-injectors: is needle length adequate for delivery of epinephrine intramuscularly?
Stecher D, Bulloch B, Sales J, Schaefer C, Keahey L
Pediatrics. 2009;124(1):65.
OBJECTIVE: Studies show that intramuscular epinephrine results in peak plasma concentrations of epinephrine faster than the subcutaneous route, and therefore, epinephrine is recommended to be administered intramuscularly. The objective of this study was to determine if the needle length on epinephrine auto-injectors is adequate to deliver epinephrine intramuscularly in children.
METHODS: Patients between the ages of 1 and 12 years who presented to a children's hospital were enrolled in the study. Ultrasound was used to determine the depth from the skin to the vastus lateralis muscle. The patient's body mass index was recorded. The data were analyzed using simple descriptive statistics, and logistic regression was used to identify variables that might predict whether or not the needle length was exceeded.
RESULTS: A total of 256 children were enrolled. Of these, 158 children weighed less than 30 kilograms and would be prescribed the 0.15 mg epinephrine auto-injector. Nineteen of these children (12%) had a skin to muscle surface distance of>(1/2)'' and would not receive epinephrine intramuscularly from current auto-injectors. There were 98 children weighing>or=30 kilograms who would receive the 0.3 mg epinephrine auto-injector. Of these 98 children, a total of 29 (30%) had a skin to muscle surface distance of>(5/8)'' and would not receive epinephrine intramuscularly.
CONCLUSION: The needle on epinephrine auto-injectors is not long enough to reach the muscle in a significant number of children. Increasing the needle length on the auto-injectors would increase the likelihood that more children receive epinephrine by the recommended intramuscular route.
Department of Emergency Medicine, Phoenix Children's Hospital, Phoenix, Arizona 85016, USA. dstecher@phoenixchildrens.com