Experts now recommend that severe life-threatening allergic reactions - known as anaphylaxis - be treated with injections of epinephrine - also known as adrenaline - into the muscles instead of just under the skin. But according to a new study in the journal Pediatrics, needles on currently available epinephrine auto-injectors are too short to reach the muscles of many children.

The study “shows that the epinephrine auto-injectors that physicians are prescribing may not be delivering the life-saving medication (into the muscles) in many children, especially those in the growing overweight population,” one of the study’s authors, Dr. Dawn Stecher, of Phoenix Children’s Hospital, Arizona, told Reuters Health.

Stecher and colleagues used ultrasound to determine the depth from the skin to the muscles of the thigh in children ages 1 to 12 years old. In the 256 children studied, 48 had skin to muscle surface distances that were greater than the length of the needles recommended for their weights.

The higher the ratio of height to weight - known as the BMI - the less likely it was that needles would reach go deep enough to deliver the epinephrine to their muscles.

“Increasing the needle length on the currently available auto-injectors would ensure that children are receiving epinephrine by the recommended route,” the authors conclude.

SOURCE: Pediatrics, July 2009.