Severe respiratory complications as a cause of poor outcome of influenza A (H1N1sw2009) in obese patients

Abstract

Summary. Thirty three medical records and postmortem examination reports of patients died from influenza A virus (H1N1sw2009) in October and November, 2009, in the Transbaikal Territory were analyzed. The patients were divided into two groups. The first group consisted of 22 patients with obesity and the second group consisted of 11 patients with normal body weight. There was no difference between the groups in age, gender structure, and duration of the disease. Causes of death were pneumonia and progressive respiratory failure. The rate of acute respiratory distress syndrome was similar in both the groups. Thrombosis of various locations was seen more often in obese patients. A tendency was found to a higher rate of rhabdomyolisis, acute canalicular necrosis and intravascular coagulation blood syndrome in obese patients. Additional risk factors in those patients were diabetes mellitus, pancreatitis, and hypertension. Possible reasons of severe course of influenza A virus (H1N1sw2009) infection in obese patients, such as alveolar hypoventilation, production of proinflammatory cytokines by the fat tissue resulting in poor immune response, coagulation and metabolic disorders have been discussed in the article. All these conditions were responsible for complications and exacerbations of concomitant diseases but could not justify high mortality rate in this pandemic influenza A virus infection. The severe course of the infection may be attributable to virus A (H1N1sw2009) ability to damage the mitochondrial protein PB1-F2 and intervene into the fat exchange. Thus, obesity was the most considerable risk factor for death during influenza A virus (H1N1sw2009) outbreak in the Transbaikal Territory due to aggravation of underlying metabolic disorders by specific effects of pandemic influenza virus A strain.