Researchers from Brazil have performed the first autopsies, finding a pattern associated with H1N1 flu deaths from pneumonia. The findings are hoped to lead clinicians to better management of H1N1 flu and pneumonia by providing clues about the need for antibacterial and antiviral medications to limit lung damage and deaths from the pandemic flu.
"The lack of information on the pathophysiology of this novel disease is a limitation that prevents better clinical management and hinders the development of a therapeutic strategy," said lead author, Thais Mauad, M.D., Ph.D., associate professor of the Department of Pathology at São Paulo University, in Brazil.
The study, due for publication January 1 in the American Journal of Respiratory and Critical Care Medicine, found that 75 percent of 21 patients autopsied who died from H1N1 influenza had underlying medical conditions such as cancer or heart disease. The patients died in São Paulo with confirmed H1N1 infection in July and August, 2009.
One fourth of those autopsied with H1N1 flu had no underlying medical condition. All of the H1N1 patients who died experienced rapid progression of flu symptoms that lead to death, and were between age 39 to 50.
According to Dr. Mauad, body aches and fever were less frequently present in patients who died from rapid progression of respiratory symptoms associated with H1N1 flu. "Most patients with a fatal form of the disease presented with difficulty breathing (dyspnea), with fever and myalgia being less frequently present."
All of the patients who died from H1N1 flu had acute lung injury that followed three distinct patterns. “All patients have a picture of acute lung injury," said Dr. Mauad. "In some patients this is the predominant pattern; in others, acute lung injury is associated with necrotizing bronchiolitis (NB); and in others there is a hemorrhagic pattern." Bronchiolitis is an inflammation of the small airways in the lung. Necrotizing refers to destruction of the lung tissue.
Patients with underlying medical conditions such as heart disease and cancer who died from H1N1 flu were more likely to have a hemorrhagic lung condition. Bacterial co-infections were associated with necrotizing bronchiolitis (NB).
“It is important to bear in mind that patients with underlying medical conditions must be adequately monitored, since they are at greater risk of developing a severe H1N1 infection," said Dr. Mauad. In these patients, H1N1 infection may present as a potential fatal disease, requiring early and prompt intensive care management, including protective ventilation strategies and adequate hemodynamic management. "We found that 38 percent of these patients had a bacterial infection (bronchopneumonia). This has important consequences because these patients need to receive antibiotic therapy, in addition to antiviral therapy."
Cytokine storm was also found to play a role in deaths from H1N1 influenza. Cytokine storm leading to H1N1 flu deaths is the result of an overly vigorous inflammatory response that causes acute lung injury.
The scientists say the first autopsies uncovering distinct patterns of infection from H1N1 flu in the lungs should lay some groundwork for a better understanding of the disease. "We would like to deepen our efforts into the understanding of the immune responses in cases of severe infection," said Dr. Mauad. "This could ultimately lead to new therapeutic approaches”.
source: examiner
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