Autoinjector needle length
The most effective autoinjector needle length to administer adrenaline
is unknown because the certainty of evidence is very low (supplement
S5i). Studies measured the distance between skin and muscle rather than
measuring the resulting serum plasma adrenaline concentration or speed
of delivery.
Two consecutive case series in adults found that needle length of 14.3mm
or 15.2mm may be too short to reach the muscle for one to two fifths of
women (very low certainty, confidence intervals not reported).11Song
TT, Nelson MR, Chang JH, Engler RJ, Chowdhury BA. Adequacy of the
epinephrine autoinjector needle length in delivering epinephrine to
the intramuscular tissues. Ann Allergy Asthma Immunol
2005;94(5):539-542.,22Tsai G, Kim L, Nevis
IF, Dominic A, Potts R, Chiu J, Kim HL. Auto-injector needle length
may be inadequate to deliver epinephrine intramuscularly in women with
confirmed food allergy. Allergy, Asthma & Clinical Immunology
2014;10(1):39.
Another consecutive case series found that 29% of children under 15kg
may be at risk of having an autoinjector injected into bone with a
needle length of 12.7mm (very low certainty, CI not reported).33Kim
L, Nevis IF, Tsai G, Dominic A, Potts R, Chiu J, Kim HL. Children
under 15 kg with food allergy may be at risk of having epinephrine
auto-injectors administered into bone. Allergy, Asthma & Clinical
Immunology 2014;10(1):40.