Clinical Lab Field Story

In late September 2006, a strange thing occurred in the neonatal intensive care unit at a midwest hospital: A premature baby weighing less than two pounds developed a nose bleed. Severely underweight premature children face a myriad of health challenges, but nose bleeds are not typical. The NICU clinicians were concerned enough to ask the lab to run some tests.

Kim Pleus, a clinical lab scientist, ran a coagulation test quickly and called the NICU staff immediately with the results. The level of heparin in the blood sample from the baby was extremely high.

“Usually when we get these kinds of results we think it’s heparin contamination,” Kim said. “Sometimes, the nurse may not shut off the line so we don’t get a good sample. So I called the nurse to find out how the blood was drawn and she said that she had shut the heparin off on the patient. They believed it was a good sample, which meant that the results might be right. I just knew that something was not right. We don’t get those kind of results on babies”

Premature children have intravenous lines to deliver various fluids and medications. These lines are prone to blood clotting so they are flushed with small doses of the blood thinner heparin. These doses are premeasured in neonatal “hep-lock” vials to avoid confusion with adult heparin, which is dosed 1,000 times higher than neonatal doses.

Not long after the first sample arrived, Kim received another sample from a separate premature baby in the NICU who was struggling. Based on the extremely high level of heparin in the first baby’s sample, Pleus chose to add a coagulation test, called the thrombin clotting test, to the menu of tests for this second child.

“When it got to the second and third baby, I just added the test on,” Kim said. “It would have taken a lot longer to have gotten the suspicious results and then add the thrombin clotting test back on and then put the sample back on the instrument.”

The second baby also had a dangerously high level of heparin in its blood sample. “I called the doctor on the second set of results because I just couldn’t believe that I was getting these results on two different babies,” said Kim. “That’s when I got really nervous. We don’t get to see that very often on one baby let alone two babies. The doctor was understandably upset at that point. She knew that something wasn’t right when they got the results on two different babies.”

After the sample from the third child came back positive for excessive heparin, Kim called the doctor again. “I said something is not right here. And that’s when she told me what had happened. That’s when they finally figured it out.”

Nurses retrieved what they thought were pediatric doses of heparin from the automated medicine cabinets on their unit. It was later revealed that a pharmacy technician had mistakenly loaded these units with adult doses of heparin, which is 1,000 times more potent than the pediatric dosage. The adult dose is 10,000 units/ml and the pediatric hep-lock dose is 10 units/ml. The bottles are very similar except for color of the label and the labeling.

When medication is withdrawn from an automated pharmacy dispensing unit, an employee code and patient code must first be entered before the prescribed drug can be removed from the locked cabinet. The system provides multiple fail-safes to prevent medication error, but cannot avert errors that result from the faulty loading of the cabinet, which is what happened in this case.

This error led to the deaths of three of the infants, but because of the fast thinking of Kim Pleus, three other babies who were also given the adult heparin doses survived. They were treated for heparin overdose and their lives were saved.

“I felt like I was just doing my job,” said Kim. “I’m glad that I was able to help save the other babies. I hope that everybody would have done that as part of their job. To me, an important responsibility of a clinical lab scientist is to think of the individual person when you run a sample. These samples represent individual patients, people with lives and families and friends and plans. It’s important to remember that. I’m not just running a sample, sticking it on an instrument and getting results and reporting it. You always have to think back to the patient.”