Intramuscular gluteal injections in the increasingly obese population: retrospective study
BMJ 2006; 332 doi: https://doi.org/10.1136/bmj.38706.742731.47 (Published 16 March 2006) Cite this as: BMJ 2006;332:637
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With the risk of stating the obvious the population selected for this
study is inherently biased. Findings clearly can not be generalized.
Overweight or obese patients are more prone to clinical problems compared
to their normal-weight counterparts and therefore more likely to get
pelvic imaging. One is even prone to suspect that an imaging study is more
likely to be ordered for patients that are harder to examine, perhaps
because of their body habitus as well.
Competing interests:
None declared
Competing interests: No competing interests
Intramuscular injections into the buttocks: are they truly
intramuscular?
Sir:
We read with great interest the excellent and informative article by
Nisbet AC [1] regarding intramuscular injections in the increasingly obese
population. We found their contribution to be well written, interesting
and of important clinical significance. In the paper the author
retrospectively reviews the pelvic computerised tomography CT) scans of
100 patients and measured the distance from the skin to ventrogluteal and
dorsogluteal injection sites. The author concluded that the gluteal
muscles are beyond the reach of the standard needles used for
intramuscular injection.
This study is supported by our findings from a recent prospective
study of 50 patients (25 males, 25 females, mean age 53 years, body mass
index ranging from 17.7-42.3 kg/m2) undergoing CT scanning of their pelvis
and receiving intramuscular buttock injections [2]. In our study, each
patient received an IM injection of their prescribed medication along with
1 mL of air into the upper outer quadrant of the buttocks prior to their
CT. CT images were subsequently analyzed by two radiologists to determine
the position of the injected air bubble. Body mass index (BMI), distance
to injection site, subcutaneous fat and muscle thickness were measured in
each patient.
In our study, only 32% of patients had successful intramuscular
injections, with the majority of injections being subcutaneous. 56% of
males had intramuscular injections while in females, the efficacy rate was
significantly lower at 8%. The rate of successful intramuscular injection
was compared with gender and also body mass index. It was found that the
probability of unsuccessful intramuscular injection correlated with
increased body mass index but also that in patients with normal body mass
indices (especially females) there was a significant rate of unsuccessful
intramuscular injection.
In, conclusion, these two studies raise the clinically important
issue of effectiveness of intramuscular injections in the increasingly
obese population. As many drugs are administered via the intramuscular
injection in to the buttock consideration must be given to the efficacy of
drug delivery and hence drug distribution even in patients with body mass
indices within the normal limits.
References
1. Nisbet [AC]. Intramuscular gluteal injections in the increasingly
obese population: retrospective study. BMJ 2006: 332: 637-638
2. Chan VO, Colville J, Persaud T, Buckley O, Hamilton S, Torreggiani
WC. Intramuscular injections into the buttocks: are they truly
intramuscular? Eur J Radiol 2006 Feb 20 (Epub ahead of print)
Competing interests:
None declared
Competing interests: No competing interests
Sir - I accept the author's general concern about increasing obesity
and the implications with regard to needle-depth reaching gluteal muscle,
however, adipose tissue is compressible.I believe that pressure on the
syringe and needle-flange will compress the buttock muscle sufficient to
facilitate deeper needle penetration than would be possible with a firmer
tissue.
This observation should be borne in mind when making calculations of
penetration depth.
Competing interests:
None declared
Competing interests: No competing interests
Dear Editor,
We agree that standard available needles may be inappropriate for gluteal
intramuscular injections especially when the incidence of obesity is
increasing. However, this article probably exaggerates the problem for the
following reasons.
Firstly, there are other preferred sites for
intramuscular injections e.g. mid-deltoid, rectus femoris and vastus
lateralis ( Reference 1- Workman B,Safe injection techniques. Nurs Stand,
1999; 13(39):47-52).It has been highlighted that simpler clinical
parameters like the weight of the patient, muscle mass of the injection
site and the amount of subcutaneous fat should be assessed for choosing
the correct needle length ( reference 2- Lenz CL, Make your needle
selection right to the point. Nursing (US), 1983; 13(2), 50-51). In this
study the sole criteria for the assessment of subcutaneous fat at gluteal
region was the need to undergo the CT scans of the pelvis without
mentioning the indication for which this was performed. Without knowing
the underlying indication it is hard to estimate how many of these
patients would have required gluteal intramuscular injections.
Secondly,
antiemetics and analgesics are the common medications given through
intramuscular route. However gluteal region is not the most practical
intramuscular injection site in 25 yrs- 65 yrs age group.These patients do
not lie still in the bed.They either sit, stand, walk around or for social
reasons prefer the other sites.
Thirdly, the gluteal region is more often
used site for intramuscular injections in children who are held by their
parents and that age group was excluded from this study.
Fourthly, the non-ambulant and elderly patients often have atrophy of gluteal muscles and
they represent the age-group of the patients who are more often given
intramuscular injections at gluteal region. In this study even this age
group was excluded. Surprisingly, the age was not correlated with
dorsogluteal depth for the reasons not mentioned in this study.
Therefore we think though the study tries to address an important issue,
it fails to portray the true picture.
Competing interests:
None declared
Competing interests: No competing interests
Dear Editor,
What is a longer needle? In the Royal Marsden Hospital Manual of
Clinical Nursing Procedures (5th edition), the authors suggest the
following needle lengths, based on patient weight, for gluteal
intramuscular injections:
31.5 - 40.00 kg: 2.5 cm needle.
40.5 - 90.00 kg: 5 - 7.5 cm needle.
90+ kg: 10 - 15 cm needle.
They cite Lenz (1983).
REFERENCES
Lenz CL. (1983). Make your needle selection right to the point.
Nursing83, 13(2): 50-51.
Mallett J, Dougherty L (2000), Royal Marsden Hospital Manual of
Clinical Nursing Procedures (5th edition), Oxford: Blackwell Science.
Competing interests:
None declared
Competing interests: No competing interests
Editor – Nisbit suggests that in certain patients longer needles may
be required for intramuscular injection in the gluteal region. He also
suggests this route should be avoided for most drugs [1]. I would argue
that this route should always be avoided. Positioning for an injection at
this site can be humiliating for the patient, and difficult if patient
mobility is in any way limited. Also, longer needles readily available in
general practice tend to have a larger diameter. This increases pain at
the injection site.
(1) Andrew Charles Nisbet
Intramuscular gluteal injections in the increasingly obese population:
retrospective study
BMJ 2006; 332: 637-638
Competing interests:
None declared
Competing interests: No competing interests
Dr Nisbet's study of intramuscular injection in the increasingly
obese clearly neglects one of medicine's perennial truisms: namely "There
is nothing that can't be done with a strong arm and a green needle". I
would suggest a bit more effort rather than a longer needle!
Competing interests:
Dinosaur status
Competing interests: No competing interests
EDITOR-
Nisbet describes interesting findings relating to the gluteal fat
thickness at intramuscular (I.M.) injection sites (Nisbet, 2006). His
study findings parallel those of a contemporary prospective study
concluding that a majority of assumed intramuscular injections are
actually subcutaneous (Chan et al, 2006).
With regards to Nisbet’s study, it would be useful to know the mean
and the range for the Body Mass Indices (B.M.I.) of the study sample to
help with the generalisability of the data presented. The study sample was
one that had Computerised Tomography of the pelvis requested presumably
for a variety of indications- it would be useful to know if their B.M.I.
was significantly different to the general population to begin with.
For future work in this area, it may be useful to study the gluteal
fat thickness at I.M. injection sites in patient groups who have had
repeated I.M. injections for many years say for example fortnightly
antipsychotic depot injections. These are also the groups most likely to
continue needing I.M. injections on a regular basis. This study would be
helpful as repeated gluteal I.M. injections cause local changes including
fibrosis of the muscle and presumably also affect the subcutaneous fat
pad.
Regarding the recommendation for use of longer needles, their
potential to cause more tissue trauma and subsequent fibrosis may need to
be taken into consideration, especially in the latter patient group who
need regular injections. Fibrosed muscle probably has worse blood supply
than subcutaneous tissue, and with limited injection sites, this may be
something that we need to keep in mind when informing the debate on
recommended needle size.
References:
Nisbet AC. Intramuscular gluteal injections in the increasingly obese
population: retrospective study. BMJ 2006; 332:637-638
Chan VO, Colville J, Persaud T, Buckley O, Hamilton S, Torreggiani
WC. Intramuscular injections into the buttocks: Are they truly
intramuscular?
Eur J Radiol. 2006 Feb 20; [Epub ahead of print]: PMID: 16495027
Competing interests:
None declared
Competing interests: No competing interests
Dear Editor,
Not only the bioavailability of the drug is reduced in obese
patients, when IM-injections are given in gluteal region, the risk of local
complications such as granuloma formation, erythema, pains, and reduced
movement are also high. This is again due to local accumulation of drug, the
reason is that the needle used has been too short.
Competing interests:
None declared
Competing interests: No competing interests
"Intramuscular" Gluteal Injections
I would like to comment on the interesting study by Nisbet (1)in the light of direct measurements of gluteal adipose tissue which we made on 40 autopsied patients in a Canadian hospital some 36 years ago(2). We found that most females showed a depth of adipose tissue at the dorsogluteal site greater than 43 mm, similar to Nisbet's of one greater than 35 mm in most females, males having a considerably thinner adipose layer. At the ventrogluteal site the results in Nisbet's and in our Canadian autopsy study are signicantly smaller. Our recommendation at that time was for the ventrogluteal site to be used for intramuscular injections using a suitably long needle; to ensure a truly intramuscular injection the iliac bone could be first touched with the needle point and the needle then withdrawn slightly. In our study we could not relate the thickness of gluteal adipose tissue to the type of terminal illness of the patient and the similarity between our 1970 autopsy measurements and the 2006 CT measurements of Nesbit do not seem to substantiate his emphasis on the current "increasingly obese population" used in his Title.
The main purpose of our 1970 publication (2) was to describe four cases of injection granuloma of the buttock that presented within the previous year at our hospital. In each of these patients a large gluteal mass was removed with a clinical suspicion of a possible sarcoma. Histologically the lesion in each case proved to be one of a granulomatous reaction in the adipose tissue to fat necrosis. The fat necrosis had been induced by the misplaced "intramuscular" injection of antibiotic substances.
1. Nisbet AC. Intramuscular gluteal injections in the increasingly obese population: retrospective study
BMJ 2006; 332: 637-638
2. Michaels L, Poole RW. Injection granuloma of the buttock. Canadian Medical Association J 1970;102:626-628
Competing interests:
None declared
Competing interests: No competing interests