Vol. 7 Issue 18
Is aspiration necessary during intramuscular injection?
What is the proper administration technique for intramuscular injection (IM), and why do we use this technique? What is the reason for aspiration and is it required, especially since all vaccine administration instructions do not include it.
These are some of the recent questions about medication administration. It is important for all institutions to have policy and procedure manuals available that describe proper techniques. Staff should be able to refer to these manuals and to follow techniques as described.
When administering an IM injection, the nurse should know and use anatomical guidelines to locate the proper site:
• Don gloves;
• Cleanse the chosen site with alcohol;
• Spread the skin and subcutaneous tissue;
• Insert proper gauge and length needle quickly at a 90-degree angle;
• Slowly inject medication if aspiration results in no appearance of blood; and
• Withdraw needle, discarding used needle in a sharps container.
There can be variations with needle size and spreading of tissue because of the age and/or size of the patient. But we also may ask, can there be variations with aspiration?
The recommended technique by most nursing authorities and literature includes aspiration before injection of the medication.1 Since muscle tissue is very vascular, aspiration before injection of medication will verify the needle tip is in the muscle and not a vein or artery. This will prevent inadvertently injecting the medication directly into the bloodstream.
While there is no research into how frequently blood aspiration during IM injections occurs, our experience and anecdotal responses from other nurses show it rarely occurs but it does occur.
The standard IM injection technique was designed to use normal anatomical landmarks to locate muscle structures for delivery of medication into the muscle for absorption into the bloodstream over a 3-6 hour time period. However, since slight variations exist in vascular aspects of the muscle for some individuals, aspiration prior to injection safeguards against inadvertently injecting the medication directly into the bloodstream or the intravenous route.
Questions About Aspiration
Recently the CDC, the Advisory Committee on Immunization Practices and the American Academy of Family Physicians published immunization recommendations that question the technique of aspiration during IM injections of vaccines such as hepatitis B and rabies for all age groups.
While the CDC notes their prior recommendation was to aspirate before injection, the new recommendation states "although certain vaccination specialists advocate aspiration, no data exist to document the necessity for this procedure. If aspiration results in blood in the needle hub, the needle should be withdrawn and a new site should be selected."
This statement questions the level of evidence for use of aspiration but does not account for the theory that supports aspiration to prevent the medication from being introduced directly into the bloodstream. While reports discuss impaired vaccine effectiveness if the vaccine is injected into subcutaneous fat tissue, and the need to avoid the dorsal gluteal muscle due to potential damage to the sciatic nerve, they do not say if dangers are associated with inadvertent injection into the bloodstream.
However, reports note "variation from the recommended route and site can result in inadequate vaccination protection." Also, if aspiration occurs and results in blood in the needle, the vaccine should not be administered and another site should be selected, presumably to avoid IV injection of the vaccine. If blood draws back into the needle, a new vial of vaccine needs to be used.
Why the Concern?
The rationale for aspiration during IM injection is to prevent inadvertent IV administration of medication, which could increase the risk of severe adverse reactions. In the acute care setting, IV doses of most medications are less than IM doses. This is due to the adverse effects of most medications in high serum doses.
IM injections allow for a gradual absorption of the medication into the bloodstream and maintenance of serum levels over a period of time (3-6 hours). For example, IV doses of morphine are much lower than IM doses. The typical IV dose for a narcotic-na•ve patient is 1-3 mg injected slowly over 5 minutes. Typical IM injection of morphine for these patients is 1-7 mg.
If the IM dose is administered IV, significant cardiac and respiratory depression will result. The use of aspiration in this instance would safeguard against the large dose administered IV and against cardiopulmonary adverse effects. In the instance of IV administration of vaccines the dangers of severe reactions and anaphylaxis are rare. However, if the person reacts to the administration of the vaccine, the IV route will result in more severe effects.
Research on Aspiration
Aspiration during IM injection is still recommended by nurse educators and nursing literature because of the dangers of inadvertent administration of IM doses of medications, as well as IV vaccines.1-2
No recent experimental data exists regarding the incidence of inadvertent administration of medications or vaccines comparing the IM technique of aspiration versus non aspiration. However, this lack of data does not indicate there is no strong clinical rationale for the continued use of aspiration during IM injection.
Recently, the collective healthcare system has embraced the evidenced-based practice (EBP) movement.
Currently, meta-analysis of randomized clinical trials is placed at the top of the EBP model, nonexperimental studies (correlational, descriptive and qualitative) in the middle, and other types of non-research evidence (opinions of respected authorities based on clinical experience and theory) at the base.
Many nursing clinical practice questions lack the research studies to provide empirical data. In these situations, EBP must draw on other nonempirical sources. Therefore, while EBP promotes research utilization in practice, both research data and non-research sources of information play a role in EBP. The hierarchy of EBP helps clinicians evaluate and integrate the best evidence to support the most effective and safe interventions.
The issue of aspiration during IM injection is a situation where the level of evidence at this point does not provide empirical data. However, non-research evidence supports the continued use of aspiration for the majority of IM injectable medications. So until healthcare professionals conduct empirical data to contradict the use of aspiration, the safety benefits outweigh the drawbacks.
Based on available information on variation of individual anatomy and the dangers of inadvertent IV administration of many IM dosages, the practice of aspiration is still recommended.
1. Kozier, B., et al. (2004). Fundamentals of nursing (7th ed.). Upper Saddle River, NJ: Pearson Education Inc.
2. Potter, R. & Perry, A. (2005). Fundamentals of nursing (5th ed.). St. Louis, MO: Mosby Inc.
Darlene M. Barr is the nursing skills lab coordinator at West Chester (PA) University Department of Nursing. She also works clinically per diem for a nursing agency. Christine M. Thomas is a faculty member at West Chester University.