Critical Thinking Meets the Aspiration Debate

CDC permitting not aspirating prior to injecting vaccines should not be interpreted as applying to all intramuscular injections. Not aspirating does not pass the "risk vs benefit" or critical thinking sniff test. Nurses Safety Knowledge


Critical Thinking Meets the Aspiration Debate

I love evaluating things in life through the lens of "risk vs benefit". In health care, decision-making...comparing risk to benefit... takes on special meaning since there is no room for error in an environment where way too many errors are known to kill patients.

Surely, our first duty as nurses, as well as for other medical staff, is to "do no harm". On the whole I would like to believe that most of us live with enough fear of harming a patient that we take every measure possible to assure that no harm occurs as we go about administering what we have learned. What we learn and how safely we subsequently practice is dependent in large part on the level of expertise of those teaching us, both in school and then starting anew with our first job after graduation. Learning deeply in nursing school and through our practical training on the job following school is paramount regarding safety, and every effort should be made by those with more beside experience and by those who train nurses generally to provide the most reasonable information possible.

Teaching nurses requires non-biased, potent critical thinking skills and an ability to apply common sense in the application of new innovations and procedures as well as to the assessment of proposed changes to long-established techniques used during routine procedures. The ability to see the "big picture", and to calmly assess what us old nurses' experiences have to offer in assessing the benefit (or lack thereof) of change, is important if we are to make the best decisions possible. Change can be good as well as unbelievably harmful. With a patient-centered approach we can keep our patients safe and comfortable as we evaluate change and make sure it fits reasonably within the bigger picture, and especially does no harm.

Whether or not to aspirate before administering a medication by intramuscular injection, and the somewhat amazing debate surrounding that subject, comes to mind as an example of how we can sometimes fail to recognize that the first thing we should decide when considering a subject is whether a decision needs to be made. I posit that no decision needs to be made here because to not aspirate raises the risk of harm or death and provides no measurable benefit.

In my thirty years and one week of employment (I made the scheduler beg for that last week) in the E.R. of a regional medical center that covers a huge swath of the north Florida panhandle, I administered a lot of medications by intramuscular injection. At just three injections a day that would be over twenty-three thousand, and you can bet it was way over that. Keep in mind that there is just one of me, relative to millions of nurses out there, when I say that there were two instances when I aspirated blood into a syringe. Those were two instances when I could well have done harm, possibly great harm, to a patient. I, of course, started over in each case with fresh everything. There is no guarantee of vessel location. We are all different, and locations are determined early in our development by how tissues fold together. There may be a general road map, but street placement is not guaranteed.

In some literature it is said that no aspiration need occur because the CDC allows that for vaccination, but there is an exception, it is said, regarding the "dorsogluteal site". (No mention is made of the vastus lateralis site.) So we are to train millions of nurses that only in a given location aspiration should be employed? We have to think of a systems approach here if we are to assure safety on the whole. We must see the big picture. Aspiration must apply to all intramuscular injections, and I would include pediatric patients as well. Why would we place them at unnecessary risk?

The same literature mentioned above included a concern about pain as a result of aspiration, and the requirement that one aspirate for 5-10 seconds. Certainly, pain is just not an issue in the hands of someone with appropriate skill. Taking longer than one second to aspirate I believe to be wholly unnecessary. If the tip of the needle is in a vein, even a minuscule vein, blood will flow very quickly into the syringe as one aspirates. In obtaining a degree in biology I accessed tiny rabbit ear veins, and blood flowed instantly and freely into the syringe. Brief aspiration is plenty.

There is also mention of employing a very rapid injection to lessen the pain in pediatric patients. I don't know of anyone who enjoys pushing a needle into another person. (The first, and only time a fellow student nurse injected me in practice with 0.5cc normal saline intramuscular, she let go of the syringe, backed away a couple of feet, covered her face, and screamed long and loud. That was it for her nursing career.) My point is that any injection displaces, and to a greater or lesser extent, tears muscle, which hurts. The needle practically does not hurt. The thought of the needle hurts. If medicine is pushed slowly through the needle it has a bit of a chance to distribute, lessening the bolus effect and the tearing of muscle, and of pain. I witnessed that thousands of times, once cheering when an out-of-town physician who was with his friend in our E.R. asked me to administer an injection slowly as I described. He was the only person in all those years who actually understood the mechanics. We give shots fast because we don't want to see that needle in the patient any more than they do, but we can know and do better for our patients. The same applies to pediatric patients, too. If the shot doesn't hurt (if we don't tear the muscle) they won't be so afraid of the next shot.

Finally, I am aware of a patient who was administered epinephrine 1:1000 intravenously that was meant to be given intramuscularly. He was young and somehow managed to escape his ventricular tachycardia that that uneducated mistake triggered. Not aspirating, even when otherwise administering 1:1000 epinephrine intramuscularly per the standard into the vastus lateralis, can lead to inadvertent intravenous administration and death. There are plenty of other drugs out there that can lead to the same fate.

To extrapolate from CDC guidance (which permits not aspirating while administering vaccines) in order to justify the practice of not aspirating in general during intramuscular injections...with the exception of the dorsogluteal dangerously irresponsible, since not aspirating risks serious harm to the patient and offers no meaningful benefit.

When we are dealing with millions of trainees (optimistically) we must use a systems approach and not expect every nurse to remember exceptions to the rules of aspiration. Let's analyze by comparing risk to benefit... Aspiration hurts nothing...Not aspirating risks killing your patient.

Let's demonstrate our critical thinking skills here, and apply reason.


Aspirating during the intramuscular injection procedure: a systematic literature review -  Sisson – 2015 – Journal of Clinical Nursing – Wiley Online Library.

Jon E. “Rick” Soskis has 47 years experience and specializes in Emergency R.N. / Snakebite expert / Author.

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Specializes in Putting out fires.

I was never taught aspiration, I was taught z-track.

Specializes in Emergency R.N. / Snakebite expert / Author.

Hi...I was taught aspiration, and Z-track but only as it pertains to IM Vistaril. What we are taught surely does matter, doesn't it? Jon Soskis

Specializes in Retired from Ambulatory Surgery.

I was taught aspiration (50+ years ago) and practiced it faithfully throughout my 40 year career.  I probably aspirated blood maybe twice but why tempt fate?  I was very good at giving IM's and aspiration was simply a part of the routine moves.  If it becomes a habit, it's never missed.

Specializes in Emergency R.N. / Snakebite expert / Author.

Thanks for that. I actually aspirated blood twice. It's just not that difficult to provide the patient our best.    :)

Specializes in Community and Public Health, Addictions Nursing.
7 hours ago, Jon E Soskis said:

So we are to train millions of nurses that only in a given location aspiration should be employed?

Good question! According to the ACIP, "Aspiration before injection of vaccines or toxoids (I.e., pulling back on the syringe plunger after needle insertion but before injection) is not necessary because no large blood vessels are present at the recommended injection sites". Full text here:

7 hours ago, Jon E Soskis said:

Finally, I am aware of a patient who was administered epinephrine 1:1000 intravenously that was meant to be given intramuscularly.

I wonder how this can be avoided in the community setting when virtually all Epipens are auto-inject models. Again, I'm interested to know about the safety of the vastus lateralis site compared to other injection sites. 

Specializes in Emergency R.N. / Snakebite expert / Author.

That's a really good question. Outside of the hospital I guess that risk will remain. Inside the hospital I could be wrong but I would guess that the difference between the cost of the Epipen and a 1 ml ampoule of 1:1000 epi would rule out Epipens. A 1 ml ampoule a few years back was a dollar an ampoule...and allows for aspiration. Too, how many lay people who would administer epi in the field would know to, or actually aspirate in the heat of the moment?

Specializes in oncology.
7 hours ago, GGLynnRN said:

I was never taught aspiration, I was taught z-track.

Z-track is displacing tissue so that, when the needle is removed, the drug does not have a path out. Aspiration when it is necessary for an IM is checking if the needle is in a blood vessel.

Specializes in Emergency R.N. / Snakebite expert / Author.

Hello...Thank you for clarifying that these two subjects are not related.   :)

Specializes in Putting out fires. this explains my previous post. I was taught vastus lateralis or deltoid using z-track and never taught aspiration. 

Specializes in Peds/outpatient FP,derm,allergy/private duty.

Speaking as a nurse of similar vintage, and who worked in the clinic "shot room" where I gave every type of injection imaginable ordered by physicians from multiple specialties, gave travel shots to many people at a different employer, I can say with confidence that we have an attachment to aspirating that goes beyond evidence-based practice.

I'm not aware of a single death caused by a med given IM that inadvertently entered the circulatory system and harmed or killed a patient.  The patient who had a brush with death, I interpret as caused by a nurse violating the "right route" rule.

Therefore, stating that not aspirating risks harming the patient based on the stated rationale for including that step isn't supported by the evidence.

I think I had maybe two incidents of a blood return, and both of them were likely capillary return from allergy shots.  But the idea of just... not... aspirating ever still bothers me, regardless.

Your article reminds me (because for some reason I retain stuff like this) of a spirited to and fro we had back in 2009 if anyone is interested.

To aspirate or not to aspirate?!

Specializes in oncology.
21 hours ago, GGLynnRN said: this explains my previous post. I was taught vastus lateralis or deltoid using z-track and never taught aspiration

Great article! It talked about a couple of things. One was whether to aspirate for vaccinations:


Aspiration before injection and slow injection of the medication are not supported by research for vaccine administration.1 For all other medications, there is no evidence to support abandoning the practice of aspiration before administration. More research is needed to investigate the practice of aspiration before administering an IM injection with medications other than vaccines.9,10 The vastus lateralis and deltoid muscles are the only two sites recommended for vaccine administration because these sites do not contain large vessels that are within reach of the needle.

The conclusion was to aspirate with medications (until the evidence is in) and another conclusion was to NOT aspirate for vaccines since aspiration for vaccinations is not supported by research.

The article also describes the ventrogluteal and vastus lateralis for Z-tracking. TBH I have never attempted using the deltoid for Z-tracking.