WESTPORT, CT (Reuters Health) Nov 17 - Selecting the correct needle length
and gauge is important to achieve intramuscular administration of vaccines,
according to an editorial in the November 18th issue of the British Medical
Journal.
Dr. Jane N. Zuckerman, a senior lecturer from the Academic Centre for Travel
Medicine and Vaccines, Royal Free and University College Medical School in
London, stresses that vaccines need to be given intramuscularly to generate
an immune response and decrease the risk of adverse effects. To this end,
needle selection is very important.
In one study, with over 10,000 patients receiving intramuscular injections,
only 0.4% had a local adverse effect. Subcutaneous injections, however, can
result in abscesses and granulomas. Dr. Zuckerman suggests that the abundant
blood supply and drainage channels in muscle versus adipose tissue may
explain this finding.
"To make sure the needle reaches the muscle and that vaccine does not seep
into subcutaneous tissue the decision on the size of the needle and
injection site should be made individually for each person," Dr. Zuckerman
states. The volume of vaccine, patient age, and muscle size are also
important determinants.
Another study found significant variability in the thickness of the deltoid
fat pad. In the group studied, a standard 5/8 inch (16 mm) needle would not
have reached muscle in 17% of men and almost 50% of women. Men weighing 59
kg to 118 kg and women weighing 60 kg to 90 kg may require a 1-inch (25 mm)
needle. Women over 90 kg may require a 1.5 inch (38 mm) needle.
Dr. Zuckerman suggests that wider bore needles may allow greater dispersion
of vaccine and thereby decrease local adverse effects.
When vaccines are to be given, healthcare providers should have access to a
range of needles to achieve intramuscular injection, Dr. Zuckerman
concludes.
BMJ 2000;321:1237-1238