Severe Swine Flu Could Lead to Blood Clots in Lungs: Study

Oct. 15 -- WEDNESDAY, Oct. 14 (HealthDay News) -- People who are severely ill with the H1N1 swine flu run the risk of blood clots in the lungs, University of Michigan researchers say.

And because standard chest X-rays may not be able to spot the potentially fatal condition, more sophisticated CT scans may be needed to identify the risk, the researchers said.

Technically called a pulmonary embolism, the condition occurs when one or more arteries in the lungs become blocked. Aggressive use of blood-thinning drugs can reduce the risk of death, the researchers said.

"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," study lead author Dr. Prachi P. Agarwal, assistant professor of radiology at the University of Michigan Medical School, said in a university news release.

"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," he added.

The Michigan study included 66 patients diagnosed with the H1N1 swine flu; 14 of those were so sick they had to be admitted to the intensive-care unit.

All 66 patients underwent chest X-rays to look for problems caused by the H1N1 virus. Pulmonary embolisms were detected by CT scans in five of the 14 intensive-care unit patients. The researchers added that initial chest X-rays were normal in more than half of the patients with H1N1 infections.

"These findings indicate that imaging studies would have to be repeated in severely ill patients to monitor disease progression," said study co-author Dr. Ella Kazerooni, director of the University of Michigan's division of cardiothoracic radiology. "It's important to heighten awareness not only among the radiologists, but also among the referring clinicians."