Chest X-Rays Often Appear Normal in Patients With Swine Flu

People with H1N1 flu have normal chest x-rays more than half the time, while patients who are severely ill tend to be at high risk for pulmonary embolism (PE), says a study published this month in the American Journal of Roentgenology.

In the study, researchers from the University of Michigan at Ann Arbor reviewed records of more than 60 patients thought to have the H1N1 virus. The patients were split into two groups: those in the first group were all older (average age: 43), had been admitted to the ICU, and needed mechanical ventilation. The second group (average age: 22) were treated as outpatients and did not need mechanical ventilation. All the patients had chest X-rays and/or CT scans. Of the 66 patients, 42 percent showed abnormal X-rays. Patients who were ill enough to need mechanical ventilation suffered from bilateral extensive airspace disease, putting them at high risk for PE.

The study has one weakness, notes Vineet R. Jain, MD, in a review of the study. The researchers did not always have the initial radiographs of those patients who ended up on mechanical ventilation, and having access to these tests could have shed more light on their condition.

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