U-M researchers find those with severe H1N1 at risk for pulmonary emboli

ANN ARBOR, Mich. — University of Michigan researchers have found that patients with severe cases of the H1N1 virus are at risk for developing severe complications, including pulmonary emboli, according to a study published today in the American Journal of Roentgenology.

A pulmonary embolism occurs when one or more arteries in the lungs become blocked. The condition can be life-threatening. However, if treated aggressively, blood thinners can reduce the risk of death.

"The high incidence of pulmonary embolism is important. Radiologists have to be aware to look closely for the risks of pulmonary embolism in severely sick patients," said Prachi P. Agarwal, M.D., assistant professor of radiology at the U-M Medical School and lead author of the study.

"With the upcoming annual influenza season in the United States, knowledge of the radiologic features of H1N1 is important, as well as the virus's potential complications. The majority of patients with H1N1 that undergo chest X-rays have normal radiographs. CT scans proved valuable in identifying those patients at risk of developing more serious complications as a possible result of the H1N1 virus," says Agarwal.

Working with Agarwal on the research were Ella Kazerooni, M.D., director of U-M's division of cardiothoracic radiology and professor of radiology and Sandro K. Cinti, clinical assistant professor in U-M's Department of Internal Medicine. The research included 66 patients diagnosed with the H1N1 flu. Of those, 14 were patients that were severely ill and required Intensive Care Unit admission.

All 66 patients underwent chest X-rays for the detection of H1N1 abnormalities. Pulmonary emboli were seen in CT scans on five of the 14 ICU patients.

Another important finding is that initial chest radiographs were normal in more than half of the patients with H1N1, says Kazerooni.

"These findings indicate that imaging studies would have to be repeated in severely ill patients to monitor disease progression," said Kazerooni. "It's important to heighten awareness not only among the radiologists, but also among the referring clinicians."

There was no outside funding for the research.

The study will be published in the December issue of the AJR.