Researchers have reported in the online version of American Journal of Roentgenology (AJR) that H1N1 may cause blood clots and other unusual damage in the lungs. Two studies show the need to check X-rays and CT scans for unusual features. The study also pointed out that H1N1 can be tricky to diagnose in some of the sickest patients. While H1N1 remains for the most part a mild illness, it is sickening many younger adults and older children who usually escape the worst effects of seasonal flu. These studies will be appear in print in the December 2009 issue of the AJR.
Unusual Lung Changes
“It is essential that clinicians be able to recognize possible cases of pandemic H1N1 influenza in high-risk groups so that they order the appropriate diagnostic tests, begin specific antiviral therapy, and prepare to provide intensive supportive measures as needed,” noted Dr. Daniel Mollura of the National Institutes of Health Clinical Center in Maryland and colleagues.
Mollura’s team found irregularities called ground-glass opacities in the patient’s lungs using a CT scan. Although the patient was severely ill and had a fever, he tested negative for flu and doctors did not treat him for it. The man died five days after he went into the hospital and the autopsy confirmed he had swine flu. The lung lesions seen on his CT scan matched lung damage done by the virus, Mollura and colleagues said.
In another study in the same journal, CT scans of patients with severe cases of swine flu showed many had pulmonary emboli, which block the arteries in the lungs, a team at the University of Michigan found.
Anticoagulant drugs can break up these clots and save lives.
Dr. Prachi Agarwal and colleagues examined 66 patients diagnosed with H1N1, 14 of them who were in the intensive care unit. All 66 got standard X-rays, which can show if a patient has pneumonia. They performed enhanced X-rays known as computed tomography or CT scans on 15 of the patients, 10 of them who were in the ICU on ventilators to help them breathe. Five of the ICU patients had the blood clots in the lungs, Agarwal reported. “Our study suggests that patients who are severely ill with H1N1 are also at risk for developing pulmonary emboli, which should be carefully sought for on contrast-enhanced CT scans,” Agarwal said in a statement.