The order was written correctly in the electronic medical record (EMR) for phenytoin, 800 mg IV. The drug-dispensing machines stocked phenytoin in 250 mg/1 mL vials. The correct dose therefore would require 4 vials and be equal to 3.2 mL to be added to a small IV bag. The nurse misread the order as 8000 mg (8 g) and proceeded to administer that dose to the patient, which was a 10-fold overdose and 2 to 3 times the lethal dose. The patient died several minutes after the infusion.
This nurse had to work hard to make the error:
An audit of the pharmacy system revealed that the nurse had taken 32 vials out of 3 different pharmacy dispensing machines to accumulate 8 g of IV phenytoin. Moreover, the nurse had to use two IV bags and a piggyback line to give that large a dose.
And all this had to go unnoticed by people nearby:
Within 100 feet of the ED nurses' station were several ED doctors, a number of nurses, and a pharmacy with a PhD pharmacist on duty. The nurse did not ask anyone to check her calculations, nor did anyone notice or comment when she was moving around the unit amassing the vials needed for the dose.
What do we conclude? Elizabeth Manias writes:
In this case, the nurse made a series of cognitive errors that contributed to a 10-fold overdose of phenytoin. The nurse did not recognize that it was unusual to use 32 vials of phenytoin to obtain the required dose. She did not acknowledge that it was uncommon to need two intravenous (IV) fluid bags to administer the single dose of phenytoin. The nurse also did not double-check the IV medication with another clinician. Most important, she appeared not to know the toxic dose of the medication she was administering.
Incompetent? No necessarily:
Every day, well-intentioned clinicians carry out their medication activities in environments that are set up to fail them. Mistakes with medications occur not because a clinician has been incompetent by making an error, but rather because this single act is the final link in a chain of failures.
Indeed, some of the worse mistakes come from good intentions:
In this case, one can imagine a well-meaning nurse trying to do everything she could to collect the medication for her allocated patient. Although her persistence is laudable, it is probably also an example of anchoring bias. When the order is so difficult to complete and so unusual, it is far more likely to be in error than to reflect an idiosyncrasy of the prescribing physician or the patient. While the nurse was undoubtedly trying to be helpful, the instinct of all clinicians has to change from one of "this is unusual, but I'll just get it done" to "this is unusual, I wonder whether it is correct."
So back to the nurse in Brazil. I don't know if she was incompetent. I do know that variations of the kind of error she made happen thousands of times, even by highly trained folks. Manias concludes with these take-home points:
- Good communication between clinicians is a key factor to minimizing the risk of producing a medication error.
- Clinicians can train themselves to recognize warnings associated with medication errors.
- Medication errors generally occur as a result of system failures rather than faults produced by particular people.