What is a critical lab value? it depends, Hopkins researchers find

When it comes to lab tests, interpreting the clinical importance of an out-of-range result depends on how much experience a physician has, suggests research from the Johns Hopkins Children's Center.

Investigators are presenting their findings at the American Academy of Pediatrics Conference Oct. 26 through Oct. 30 in San Francisco.

In the study involving 31 residents, six fellows and 10 senior attending physicians in the neonatal intensive care unit (NICU) at Hopkins Children's, senior, more experienced doctors (attending physicians) were less likely to want certain abnormal results reported to them immediately. By contrast, the less experienced doctors (residents) were most likely to want all out-of-range values right away, while those in the middle of the experience curve (fellows) fell in between.

“Theoretically, there should be no difference in which abnormal values doctors consider critical to get by instant pager, so we were quite surprised to see how their views of ‘critical' varied,” says lead investigator Theodora Stavroudis, M.D., a neonatologist at Hopkins Children's.

The differences could mean that younger, less experienced doctors are simply more anxious and prefer to err on the side of caution, researchers speculate.

“With increased experience, you tend to learn which alerts you can ignore safely and which ones you can't,” says senior investigator Christoph Lehmann, M.D. “Unfortunately, this isn't something you can teach in medical school, but it is something that comes with experience.”

Researchers asked doctors to define which out-of-range lab values they considered critical enough to require the lab to page them. Under the current system, a lab technician reports the lab results to a nurse, who then reports them to a doctor, which means that up to 20 minutes can pass before a doctor finds out about a patient's abnormal labs. In an effort to cut lab-to-doctor time, streamline communication and improve patient safety, Hopkins Children's researchers are preparing to launch a system that feeds critical lab values directly into a doctor's pager.

To avoid overload, however, it was important that only truly critical results—those signaling true urgency or emergency in terms of clinical care—be sent. But which out-of-range results require an instant alert and which ones can wait" Four out of 15 abnormal lab values (low ionized calcium, high sodium, high potassium and high creatinine) generated the most difference in opinion. Most attending physicians said none of these required a page. Most fellows said all four but high creatinine should trigger a pager alert. Most residents said pagers should go off for all four, except high sodium.

The study also points to the need to define what truly critical values are for newborns and stop extrapolating from “adult” lab values, an archaic, round-about system that is currently the status quo in hospitals nationwide, researchers say.

Since last spring, when this study was conducted, the Hopkins NICU has moved on to use both the current and the new systems side by side, allowing researchers to compare them “in action.”

This study is part of Hopkins' ongoing efforts to prevent medical errors and improve patient safety. Traditionally, intensive care units have been the most vulnerable to errors because of the severity of cases and the many distractions in the environment.