Case Study: Can You Prevent This Medical Error?

What caused the seizures?

This article presents a case study published in the Annals of Internal Medicine in 2002. An older patient was much improved after a difficult postoperative course. On the morning of her planned transfer out of the ICU, she had a grand mal seizure and died as a result of medical error. I will lead you through the case step-by-step. See if you can prevent this error from happening again.

Updated:   Published

What caused the seizures?


Ms. Grant (not her real name), a 68-year-old woman, recent cardiac bypass

Postoperative for elective cardiac bypass with significant complications: ventilator acquired pneumonia, right-hemispheric stroke, clinically significant GI bleeding, acute tubular necrosis requiring hemodialysis

Stated on the morning of the event: "I feel good for the first time in a long time."

Morning of a planned transfer to step-down patient was observed coughing and moving head and extremities in an uncontrolled manner. BP 220/95 mmHg.

No history of seizure or seizure medications

Blood was drawn, the patient was taken for a CT to rule out a stroke or cerebral hemorrhage

Serum glucose came back 0 during transport to CT lab

The patient died after being in a coma on life support for 7 weeks.

What happened here? A woman well on her way to recovery from a difficult postoperative course was about to be transferred from the ICU to a step-down unit. What caused the seizures? Keep reading to find out (Link to full article is at the end of this blog post)1.


The Institute of Medicine published a report in 2000 called "To Err is Human"2. This report is based on thousands of chart reviews from various hospitals in the late 80"s and 90's. Americans were shocked to find out that medical error kills the same number of people as if a jumbo jet full of passengers crashed every week, with no survivors - approximately 44,000-98,000 deaths per year. These numbers are likely a gross underestimate, with the true number being closer to 400,000 deaths per year.3Recent research suggests medical error is the third leading cause of death in the US. In a report from the British Journal of Medicine in 2016, the authors analyze how medical error fits in with the leading causes of death (heart disease and cancer are still 1 & 2) with lower respiratory disease being 3rd and accident 4th.4

I think it's safe to say that almost no one in healthcare wants to make an error. Despite our best efforts, we continue to harm patients (I talk about this in another blog post. This list shows the most common medical errors.


  • Adverse Drug Events6
  • Catheter-Associated Urinary Tract Infection
  • Central Line-Associated Blood Stream Infection
  • Injury from falls and immobility
  • Obstetrics
  • Pressure ulcers
  • Surgical site infections
  • Venous thrombosis
  • Ventilator-Associated Pneumonia

The National Patient Safety Foundation has a Vision Statement: Creating a world where patients and those who care for them are free from harm.5 We can also most likely agree that our goal is for patients to be free of harm - specifically preventable accidental harm. We cannot eradicate human error, but we can build safeguards where we know error is likely, thereby decreasing the impact of errors and potential for harm.


Back to the case study. Have you come up with some ideas for what happened to Ms. Grant? Take a look at this time line from the actual incident to give you some additional information.

0430Nurse draws blood for routine morning laboratory tests: serum glucose level is 6.72 mmol/L (121 mg/dL)
0600Medical student visits patient before team rounds. Patient is stable
0610Cardiothoracic ICU team visits; no new issues are noted. Patient is showing much improvement; team has every expectation that she will make a complete recovery
0620Patient drinks small amount of orange juice; note in chart indicates patient is stable
0635Nurses uses a straight urinary catheter to drain a patient's bladder per standing order. Patient appears well by tired; expresses a desire to nap.
0645The alarm goes off, alerting nurse to occlusion of the patient arterial line; nurse flushed line with 2 mL of heparin lock flush.
0735Day nurse receives shift change report from night nurse and assumes care of the patient.
0745Night nurse completes shift. Patient is reported to be sleeping soundly
0815Day nurse discovers a patient having seizure activity. Labetalol is given by day nurse for systolic BP >200 mm Hg. Patient physician is called.
08201 mg lorazepam given IV by the nurse for an apparent seizure
0835Neurology is called for an abrupt change in LOC
0842Emergent CT whos no evidence of intracranial hemorrhage, mass or mass effect. Lab notifies ICU that serum glucose is undetectable. 1 ampule 50% dextrose in water given IV
08551 mg lorazepam IV
09051 mg midazolam given IV push, patient intubated

Where in this time like could an error have occurred that cause Ms. Grant's death? I want to emphasize that she didn't die from any of her multiple post-operative complications. Ms. Grant died as a direct result of an unintended, preventable medical error that occurred between 0430 and 0815.

Here is the rest of the timeline, and the piece of information that will most likely lead you to the most obvious cause of her seizure.

0915Day nurse discovers bottle of regular human insulin on medication cart immediately outside patient room
09201 mg midazolam IV push
094510 mg chlorpromazine, 6 mg morphine, 2 mg midazolam IV push
09501 ampule 50% dextrose in water given
1005Glucose level of 1.3 mmol/dL (24 mg/dL) reported from lab
10151 ampule 50% dextrose in water given
11002 ampules 50% dextrose in water given
12455 mg labetalol given IV push for systolic BP of 195 mmHg
13151 ampule 50% dextrose in water given for serum glucose of 3.1 mmol/L (55 mg/dL)
RemainderBlood glucose level difficult to maintain, patient comatose

After a thorough investigation of this sentinel event, it was discovered that at 0645, the nurse flushed the patient arterial line with insulin instead of heparin. Due to the presence of insulin on the medication cart, there is no way to determine if this was the first time this had happened.


I'm teaching the fundamentals of nursing right now to brand new BSN nursing students. What follows is a description of what we teach them. The nursing role is to administer medication as prescribed while preventing error and patient harm.

What goes into "administering medication as prescribed"? In addition to being aware of federal, state, and institutional regulations, nurses also need to know the nurse practice act and their scope of practice.


  1. Generic- given by the original manufacturer which becomes the drugs official name, vs. Trade- name under which the drug is marketed.
  2. Look-alike/sound-alike drugs- list produced by the Institute for Safe Medication Practices and the Joint Commission.
  3. Classification- indicates the effect of the drug on the body/site of action.
  4. Medication Form- the form the medication comes in such as tablet, elixir, powder inhalation, often affects absorption and metabolism
  5. Pharmacokinetics describes how a medication enters the body, reach and active state for action, metabolized, and excreted when their effects have been obtained
  6. Therapeutic Effect- the expected, desired effect of taking a medication vs. Side effect- expected, unavoidable effects, at therapeutic doses. Adverse effect-undesirable/unpredictable side effects, often severe, Toxic effect- may be a result of prolonged exposure to drug or excessively high dosage, accumulation in the blood, may be lethal in their results
  7. Idiosyncratic reactions- unpredictable over or under reaction of a patient to a medication I.e. Benadryl making a child climb the walls when it should really make them sleepy.
  8. Allergic reaction- an immune response is elicited, release of antibodies by the body -Anaphylactic- life-threatening, reaction constriction of bronchiolar muscles, edema of the pharynx/larynx, severe wheezing, ShOB
  9. Timing: onset, peak, trough, duration, half-life,
  10. Route: Parenteral, SQ, I'm, IV, Non-parenteral, Oral, Sublingual- under the tongue, Buccal-mucous membranes of the cheek, Topical, Inhalation, Intraocular
  11. Measurement: Metric- mL, mg, g, L, Household- drop, cup, tbsp., tsp. , oz.


In addition, since 1893, we have been taught the 5 rights as the number one process for safe medication administration. The five rights were first seen in The Nursing Sister: A Manual for Candidates and Novices of Hospital Communities.7 Nursing sisters taught five rights to prevent error: right patient, medication, dosage, route and time. Since then, there have been an increasing number of rights: client education, documentation, client right to refuse, assessment, and evaluation of the client after the medication is administered.8The number of rights increases, but error rates do not change. I have tried to find research to support use of the 5 rights - there isn't much out there - no randomized clinical trials showing that using the 5 (or 6, 7, 8, 9) rights improves patient safety when compared to some other method of safe medication administration.

Below you will see safety guidelines from a fundamentals of nursing clinical packet. It's what we are teaching new nursing students to do to prevent medical error.


  • Maintains medical asepsis, sterile technique and standard precautions
  • Maintains proper body alignment and personal safety
  • Demonstrates appropriate use of equipment provided
  • Provides nursing care that maintains the emotional and physical safety of patients
    • and other members of the healthcare team
  • Demonstrates knowledge and identification of national patient safety goals
  • Communicates observations or concerns related to hazards and errors to patient,
    • Families and the health care team, and faculty
  • Organize multiple responsibilities and provide care in a timely manner while using
    • clinical reasoning skills to prioritize care
  • Safe
  • Accurate (each time)
  • Affect (each time)
  • With occasional or with supporting cues

And here is a clinical check-off sheet for a return demonstration for safe medication administration



It's obvious that the nurse who gave the patient insulin instead of heparin made a mistake. That nurse gave the wrong drug. That nurse didn't follow the five rights. If we stop with these statements, is it possible this error could happen again to another patient? The answer is YES. We have to go deeper if we want to prevent error. "The single greatest impediment to error that we punish people for making mistakes" Dr. Lucian Leape9


Doing a root cause analysis is required by the Joint Commission for sentinel events (I wrote about RCA in another blog. Below is the causal tree from the RCA for Ms. Grants death.



The causal tree shows that multiple factors contributed to the patient receiving the wrong drug. The committee that investigated the death came up with the following solutions:

  • Insulin was added to the automated dispensing device
  • Staff were educated to keep medications secured and not on drug cart
  • Nurses were reminded to keep med carts locked
  • Use of multi-dose vials of insulin and heparin prohibited
  • Use of saline flushes to restore patency of arterial lines required instead of heparin
  • Interdisciplinary team to examine how to expedite delivery of medications to patients

At the end of every Root Cause Analysis (I have lead many as a former Patient Safety Officer) we always ask, "If these interventions had been in place at the time of the event, could the error have occurred?" If the answer is "yes" then we get back to work. What do you think? Are there any other ideas you have for preventing this type of error? What experiences have you had with medical error?


A "second victim" is a healthcare worker who has been involved in a medical error. Second victims often experience emotional trauma, stress, financial strain, loss of job and loss of peer respect after being involved in an error. Unfortunately, I've been there (yet another blog)

If you or someone you know has been involved in a medical error, please send them to one of these sites to get support and help:

ProPublica Patient Safety Action Network Community: Patient Safety Action Network Community Public Group | facebook

Medically Induced Trauma Support System: Home - MITSS


  1. Bates, D. W. (2002). Unexpected hypoglycemia in a cricitally ill patient. Annals of Internal Medicine, 137(2), 110-116. Retrieved from: Unexpected Hypoglycemia in a Critically Ill Patient | Annals of Internal Medicine | American College of Physicians
  2. Kohn, L., Corrigan, J., & Donaldson, M. (2000). (Editors). To err is human: Building a safer health system.Washington DC: National Academy Press.
  3. Classen, D., Resar, R., Griffin, F. (2011). Global "trigger tool" shows that adverse events in hospitals may be ten times greater than previously measured. Health Affairs, 30, 581-9. doi: 10.1377/hlthaff.2011.0190.
  4. Makary, M. & Daniel, M. (2016). Medical error - the third leading cause of death in the US. British Medical Journal, 353, 1-5. doi: 10.1136/bmj.i2139
  5. Institute for Healthcare Improvement
  6. Wachter, R. M. (2012). Understanding patient safety. 2nd ED. China: McGraw Hill.
  7. Wall, B. (2001). Definite lines of influence: Catholic sisters and nurse training schools. Nursing Research, 50(5), 314-321.
  8. Potter, P. A., Perry, A. G., Stockert, P., & Hall, A. (2013). Fundamentals of nursing (8th ED.). Philadelphia, PA: Elsevier.
  9. Leape, L., Epstein, A. M., & Hamel, M. B. (2002). A series on patient safety. Journal of the American Medical Association, 288(4), 501-508.
  10. Patient Safety Action Network Community Public Group | facebook
  11. Home - MITSS

DISCLAIMER: These case studies are presented for learning purposes only and with full understanding that it is outside the scope of practice for a nurse to make a medical diagnosis. When participating, assume that a licensed healthcare provider is making the actual diagnosis, ordering all the tests and interpreting the results. You are looking at the case retrospectively to learn from the data presented – the idea is to increase your knowledge so you can sharpen your assessment and teaching skills.

Dr. Kristi Miller, aka Safety Nurse is a Certified Professional in Patient Safety. She is also a mother of four who loves to write so much that she would probably starve if her phone didn’t remind her to take a break. Her work experiences as a hospital nurse make it easy to skip using the bathroom to get in just a few more minutes at the word processor. Please read her blog, Safety Rules! on You can also get free Continuing Education at In the guise of Safety Nurse, she is sending a young Haitian woman to nursing school and you can learn more about that adventure:

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Has 33 years experience.

Yes, of course it is preventable. "the nurse flushed the patient arterial line with insulin instead of heparin. "

You can quote all the studies you want, develop all the algorithms you want. The bottom line/ root cause is the nurse grabbed the wrong vial of medication. Most likely because they were overworked. The vials are similar in size and are available without a pharmacy check.

Heparin and insulin are high alert meds. The nurse that administered it, did not have another nurse check the administration of the high alert med.


1 Article; 2,162 Posts

Specializes in Travel, Home Health, Med-Surg. Has 20 years experience.

I think it is always a good idea to do a f/u on any death etc. but agree with Been there, done that that sometimes mistakes will be made because of the nurse being overworked or constantly interrupted during medication admin. I would like to see hospital admin and nurse orgs do something about that.

Also, I am a little confused about your clinical med admin check sheet, you do a head to toe, and VS prior to medication admin as part of your med pass and check the 5 rights 3X? Sometimes all these extra steps are what causes a nurse to feel pressed for time which leads to mistakes.


4,895 Posts

Checking the 5 rights that many times is not the way to do it. It becomes too rote and mistakes happen. We did the pre-flight check once and only once paying close attention to every item in it. We didn't have time to do it multiple times even if we wanted to. If we had been forced to we also would have been forced to rush it and many people's lives would have been out at risk.


380 Posts

I've never heard of flushing an art line with heparin. Is that a standard practice?

blondy2061h, MSN, RN

1 Article; 4,094 Posts

Specializes in Oncology. Has 15 years experience.

That checklist for the student nurses is almost hilarious when you think that it's not uncommon in my area for some nurses to have 16 patients on night shift and not unheard of for patients to have meds due every 2 hours. That just isn't happening. So short cuts happen. Yes, better staffing would help. But in the meantime it's better to make a more realistic algorithm that can actually be followed so short cuts aren't necessary.


916 Posts

Specializes in Critical care.

Extra meds never belong on a med cart. I am a very firm believer in this because I almost came close to a catastrophic error once. The off-going shift left me an extra bag of insulin for my insulin drip on the med cart. I scanned out and verified another med, but when I went to hang it I accidentally grabbed the insulin bag that I forgot was there. I caught it because I always always verify that the pump matches the label on the bag and that that matches my order/MAR. Extra meds, especially high alert ones, should never be left on the med cart- it's just not worth the risk.

MunoRN, RN

8,058 Posts

Specializes in Critical Care. Has 10 years experience.

It's these sorts of errors where we often seem to miss the forest for the trees. The problem isn't the safest way to store, draw up, and administer a heparin flush in a transduced arterial line, the problem is that there is no reason for flushing these lines with heparin in the first place. There is no benefit in terms of patency, and no reason to believe there would benefit since heparin is not a thrombolytic, and once it's been instilled into the line as a flush it will quickly be pushed through by the continuous flow of fluid from the pressure bag through the transducer.

The best solution to this scenario is to stop figuring out safest way to do something that even when done correctly has no benefit and only poses the potential for harm, and just don't do it at all.


1,577 Posts

I've never heard of heparin being used to flush an art line. But why were they having to draw up meds to push? There was not continuous NS going through the line to keep it patent? Then you would flush from the bag of NS. An art line should have a transducer on it. Then the NS hooked up to that with a pressure bag to keep it going at a rate of 3mL/hr.

This scenario is kind of confusing. Maybe this is how it was done years ago, and you are pulling the scenario from then. I just don't know if why anyone would ever push a med through an art line.


4,895 Posts

LovingLife123 said:
This scenario is kind of confusing. Maybe this is how it was done years ago, and you are pulling the scenario from then. I just don't know if why anyone would ever push a med through an art line.

This wasn't done even years ago (and I'm talking three decades). The only art line I've ever pushed a med through is a UAC but that's a different animal.


6,465 Posts

The case was published in 2002 so it happened sometime before that. I will assume it was quite common still that art lines were maintained with heparinized saline (1000 units heparin/500 ml saline). Why anyone would have wanted to draw up heparin from a vial and push it to maintain an artline is what doesn't make sense.

ETA: And I dislike the fall out from people having done things that are off the if we all just go around willy-nilly doing things clearly not common/normal and killing planes full of people.

But we have had this discussion before...

Checklist is great if someone has one stable patient all night to thus take 35 minutes per medication.