Development of the Critical Values system redefined what STAT means in clinical laboratory testing turnaround times
Where did the concept of critical values and having clinical laboratories report them to referring physicians originate? How did the concept blossom into a standard practice in laboratory medicine? Given the importance of critical values, a lookback into how this aspect of laboratory medicine was developed is helpful to understand how and why this has become an essential element in the practice of medicine and an opportunity for labs to add value in patient care.
According to Stanford Medicine, critical/panic values are defined as “values that are outside the normal range to a degree that may constitute an immediate health risk to the individual or require immediate action on the part of the ordering physician.”
In an article he penned for the National Medical Journal of India, George Lundberg, MD, Editor-at-Large at Medscape, states that the practice of reporting critical values originated with a case that occurred in 1969 at the Los Angeles County-University of Southern California Medical Center. Lundberg is also Editor-in-Chief at Cancer Commons, President and Chair of the Board of Directors of the Lundberg Institute, and a clinical professor of pathology at Northwestern University.
What you’ll read below is an insider’s account of the “birth of critical values reporting.”
According to Lundberg, an unaccompanied man was brought to the hospital in a coma and an examination revealed a laceration to his scalp. The patient was admitted to the neurosurgical unit where clinical laboratory tests were performed, including a complete blood count (CBC) analysis, urinalysis, and serum electrolytes. All the test results came back normal except the patient’s serum glucose (blood sugar level) which was 6 mg% in concentration.
“The hard-copy laboratory results were returned to the ward of origin within two hours of receipt of the specimens in the laboratory. However, the results were not noticed by the house officers who were busy with several other seriously ill patients. Ward personnel also failed to communicate the lab results to the responsible physicians,” Lundberg wrote.
When hospital staff did finally notice the test result the next morning glucose was immediately administered to the patient, but it was too late to prevent irreversible brain damage. The man soon passed away.
Following this incident, the hospital developed a “Critical Value Recognition and Reporting System.” The system generated new numbers that were termed “Panic Values.”
However, “critics complained that good doctors should never panic, so the name was changed to Critical Values,” Lundberg explained.
When any of these critical test values were out of the norm, “we required the responsible laboratory person to quickly verify the result and use the telephone (long before laboratory computers) to personally notify a responsible individual (no messages left) who agreed to find a physician who could quickly act on the result. All was documented with times and names,” he wrote.
“We understand that when a physician wants something, he/she wants it, no matter what. Well, in this patient-focused approach, the physician cannot have it, except as offered by the patient-focused approach, based on TAT [turnaround times of clinical laboratory tests],” wrote George Lundberg, MD (above), President and Chair of the Board of Directors of the Lundberg Institute, and Clinical Professor of Pathology at Northwestern University in an article he penned for the National Medical Journal of India (Photo copyright: Dark Intelligence Group. Shows Dr. Lundberg in 2011 addressing the Executive War College on Diagnostics, Clinical Laboratory, and Pathology Management.)
New Clinical Laboratory Standards
Recognition of the urgency to adopt new hospital standards related to certain clinical laboratory test results came swiftly. In 1972, Lundberg was invited to publish an article explaining the new Critical Value Recognition and Reporting System in Medical Laboratory Observer.
“Within weeks, laboratories all over the USA adopted their own version of the system,” Lundberg wrote in his National Medical Journal of India (NMJI) article. “The test chosen, and critical values, were established by each medical staff. … A critical value system quickly became standard of practice as required by the College of American Pathologists (CAP) Laboratory Accreditation Program and the Joint Commission on Accreditation of Hospitals.”
According to Lundberg, “most laboratory tests that are done do not need to be done; the results are either negative, normal, or show no change from a prior result. But some are crucial.”
The original set of Critical Values included the following testing results:
- Serum sodium
- Potassium
- Glucose
- Calcium
- Bicarbonate
- Prothrombin activity
- Arterial or capillary blood gas (PO2 and PCO2)
- Platelet count
- Packed red blood cell (RBC) volume
- Blood hemoglobin
- Positive blood culture
- Positive cerebrospinal fluid (CSF) gram-stain
The list of values were later expanded to include “vital values.” These values describe lab results for which “action” is important, but where timing is less urgent. Examples of vital values include:
- Positive Pap smear for cancer of the cervix.
- Positive sputum culture for tuberculosis.
- Positive mammogram for breast cancer.
STAT Lab Orders Redefined
Lundberg and his colleagues went on to redefine what constitutes a laboratory test and what renders a test successful. They discussed laboratory procedures with committees of clinicians, lab personnel and patients, and reorganized hematology, chemistry, and toxicology based on the turnaround time (TAT) of tests.
“We ‘started the clock’—any and all days/times 24×7—when a specimen arrived at some place within the laboratory, and stopped the clock when a final result was available somewhere in the laboratory,” Lundberg wrote in NMJI. “We categorized all tests as: less than one hour, less than four hours, less than 24 hours, and more than 24 hours, guaranteed, 24×7. As a trade-off, we abolished the concept of ‘STAT’ orders … NO EXCEPTIONS. The rationale of each TAT was the speed with which a result was needed to render proper medical care that mattered to the welfare of the patient, and, of course, that was technically possible.”
Since then, very little has changed for the Critical Values System over the past 50 years. The majority of values added have fallen under the “Vital” category and not the “Critical” category. Today, most health systems and clinical laboratories create their own internal processes and procedures regarding which values need to be reported immediately (critical), which values are not urgent (vital), and how those results should be handled.
—JP Schlingman
Related Information:
The Origin and Evolution of Critical Laboratory Values
Critical Laboratory Values Communication: Summary Recommendations from Available Guidelines