Abstract

The HIN1 influenza A virus infection has spread rapidly worldwide, and although it is believed to have a low mortality rate, once the virus reaches the acute refractory respiratory insufficiency phase, the mortality rate increases drastically. This study reports the results of 10 clinical case studies; the patients presented signs and symptoms of acute respiratory insufficiency and were positive for the H1N1 influenza A virus. The characteristics of the patients were the following: mean age was 28.5 ± 15.4 SD., the mean time of patient hospitalization was 12.5 days ± 10.9 SD., the mean values of interleukin 6 were: 17.8 ± 9.9 SD., the mean level of SaO₂% was 91.3 ± 2.5 SD., the mean values for respiratory frequency were 28.8 ± 4.2 SD., and the mean values of arterial PO₂ were 59.99 ± 9. The most frequent findings on high resolution computerized tomography findings were the thickening of the peribronchovascular space (90%), followed by intralobular septa thickening (50%), subpleural septa thickening (30%), bronchioectasis (40%), mosaic image of perfusion (40%), and pulmonary condensation zones (30%). Two patients required non-invasive mechanical ventilation that was set to a low exhaled tidal volume of 200 ml for the patient weighing 42 kg and 300 ml for the patient weighing 60 kg.  The findings on the HRCT in these patients represent a precocious interstitial lung lesion. The authors believe that an early intervention could prevent the disease progression and the onset of the refractory phase that subsequently leads to hypoxemia and diffuse alveolar damage.

Key words: H1N1 influenza A virus infection, non-invasive mechanical ventilation, high-resolution computerized tomography.