Not surprisingly, physicians working in a big city hospital emergency room are under plenty of stress.

A Michigan State University researcher has now shown how this stress affects the care of their patients.

The more stress an emergency room physician experienced, the more likely he or she was to make a minor mistake, also known as a “near miss” among hospital staff, according to a new study led by Bengt Arnetz and published in the journal BMJ Open.

Researchers took blood and saliva samples from 28 emergency room resident physicians before and after their shifts to check for biological stress markers, Arnetz said, who is chair of the MSU College of Human Medicine’s Department of Family Medicine. After their shifts, the doctors were questioned about the number of critically ill patients and trauma victims they treated and how many near misses they made.

The result: the physicians who reported the most near misses had the highest biomarkers for stress.

“Stress among physicians is not just perception,” Arnetz said. “It has a biological affect and that biological affect might impact the wellbeing of patients.”

The study was conducted in the emergency department of the Detroit Medical Center, which defines near misses as “any process variation that did not reach the patient, employee or visitor, but for which a recurrence carries a significant chance of a serious adverse event” – in other words, a mistake that, if repeated, could harm a patient.

Arnetz has been investigating psychophysiology – the relationship between the brain and the body – since 1983 when a hospital in his native Sweden hired him to look into the health of its medical providers. He has done previous studies on how workplace stress affects workers’ productivity.

“The more stress in general in an organization, the less efficiently it is run,” Arnetz said.

His latest study is the first that associates near misses with biomarkers of stress, including cortisol, a stress hormone found in saliva. The researchers also took blood samples, looking for markers of inflammation in the brain, which increases in stressful situations.

In addition to contributing to errors in patient care, stress can negatively affect the cardiovascular health of physicians, Arnetz said.

“Very few emergency physicians work past 50,” he said. “They burn out.”

Those in the current study were young physicians in their second and third years of residency, a continuation of their education after graduating from medical school. Some stress might be self–induced by the residents unsure of their own medical skills and afraid to ask a supervising physician for help, Arnetz said.

“That’s a dangerous combination,” he said. “We’re trying to move the whole thing from being punitive.”

Arnetz hopes to conduct a follow–up study of whether the near misses caused by stress are associated with poor outcomes for patients. Further research also could look for ways to help emergency physicians reduce stress, he said.