NEW YORK NURSE: May 2008
by Antonie Hiemer, MS, RN, SUNY Institute of Technology, for the Foundation Center for Nursing Research Planning Committee
For many years, nurses have routinely given intramuscular (IM) injections. Historically, physicians decided which site would be used for the injection, but increasingly, physicians give nurses the autonomy to decide on the best site. Injecting IM medications outside of the muscle could possibly result in a poor response to the medication or adverse effects. Nurses need to find a site with adequate muscle mass for the amount of medication to be injected.
According to Potter & Perry (1999), the gluteal muscles are the most frequently used muscle for IM injections in healthy adults. There has been limited research on IM injections, with only one previously known publication in 1982 by Cockhott, Thompson, Howlett & Sealey. This study concluded that, using a 35 mm needle, fewer than 15% of men and 5% of females would receive IM injections. According to the researchers, using the standard technique for IM injections in the gluteal area would result in depositing the medication in the subcutaneous area.
Recently, Burbridge (2007) conducted a follow-up study to assess the success of IM injections. It validated the previous research study’s conclusion, with only a slight variation possibly due to the use of longer needles. Using CT scans, the researchers assessed the thickness of the subcutaneous fat (between skin and muscle) in the gluteal region on the subjects. An analysis of 298 CT scans (150 males and 148 females) revealed a significant difference in fat thickness. Male subjects had an average of 23.1 mm of gluteal fat compared to female subjects with an average of 33.2 mm of gluteal fat. The study concluded that a 37 mm needle would not have reached the gluteal muscle as it should have in 21 of 150 male subjects (14%) and 81 of 148 female subjects (54.7%).
According to this study, 34.2 % of IM injections would be given into subcutaneous tissue, instead of muscle.
Medications given into the subcutaneous tissue could result in an alteration of the anticipated action of the medication administered. RNs need to be aware not only of the importance of where the medication should be delivered, but also how that delivery can be accomplished. The Burbridge study focused only on the gluteal muscle; however, to ensure complete and accurate delivery of medication, the nurse needs to consider using alternative sites.
Alternative sites include the vastus lateris (thigh muscle) or the deltoid (the arm muscle). The RN must select a site and carefully identify landmarks to prevent damage to nerves or surrounding structures, based on the patient’s medical status as well as on the amount and type of medication to be administered.
As a nurse, you should feel confident that your patient is receiving his or her medication via the right route by ensuring proper delivery of IM medication. The Burbridge study reveals a failure rate of 34.2%, which is not acceptable. Other sites can guarantee delivery into the muscle without the risk of injection into subcutaneous tissue.
Nurses need to be aware of the relationship of muscle mass, subcutaneous tissue, and needle length used during an IM injection. In addition, it is important to continually assess your knowledge and techniques by reading articles, attending workshops, and thinking about your practice. This will ensure that your patients are receiving their medication properly. To learn more, you are strongly encouraged to read the complete article by Burbridge, referenced below.
Burbridge, B. E. (2007). Computed tomographic measurement of gluteal subcutaneous fat thickness in reference to failure of gluteal intramuscular injections. Canadian Association of Radiologists Journal, 58(2), 72-75.
Cockhott, P. W., Thompson, G.T., Howlett, L. J., & Sealey, E. T. (1982). Intramuscular or intralipomatous injections? New England Journal of Medicine, 307, 356-358.
Potter, P. A., & Perry, A. G. (1999). Basic nursing a critical thinking approach (4th ed.). St. Louis: Mosby.