CT Scans Show Patients with Severe Cases of H1N1 Are at Risk for Developing Acute Pulmonary Emboli

Researchers utilizing computed tomography (CT) scans have found that patients with severe cases of the Influenza A virus H1N1 flu are at risk for developing severe complications, including pulmonary emboli (PE).

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

The study, performed at the University of Michigan Health Service (Ann Arbor, USA), included 66 patients diagnosed with the H1N1 flu. Two study groups were formed. Group 1 consisted of 14 patients who were severely ill and required intensive care unit (ICU) admission. Group 2 consisted of 52 patients who were not severely ill and did not require ICU admission.

All 66 patients underwent chest X-rays for the detection of H1N1 abnormalities. Ten patients from the ICU group and five patients from the largely outpatient group, underwent CT scans. "Pulmonary emboli were seen on CT in 5 of 14 ICU patients,” said Prachi P. Agarwal, M.D., lead author of the study. "Our study suggests that patients who are severely ill with H1N1 are also at risk for developing PE, which should be carefully sought for on contrast-enhanced CT scans,” Dr. Agarwal said.

The research was published online October 14, 2009, in the American Journal of Roentgenology (AJR).

"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 undergoing chest X-rays with H1N1 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, and for identifying a greater extent of disease than is appreciated on chest radiographs,” concluded Dr. Agarwal.

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