Radiological prognostic factors in patients with pandemic H1N1 (pH1N1) infection requiring hospital admission

Abstract

The aim of this study was to determine the radiologic findings associated with admission to the intensive care unit (ICU) and the development of acute respiratory distress syndrome (ARDS) in patients with pH1N1 infection. One hundred and four patients (15-96 years) with laboratory-confirmed pH1N1 infection seen at the Emergency Department from July to December 2009 who underwent chest radiographs were studied. Radiographs were evaluated for consolidation, ground-glass opacities, interstitial patterns, distribution, and extent of findings. Eighty-seven (83.7%) of the patients were managed in the ward, and 17 (16.3%) patients eventually required admission to the ICU. All patients admitted to the ICU showed abnormalities on the initial radiograph. The presence of consolidation, multifocal, diffuse, and bilateral involvement on the initial radiograph was associated with a statistically higher risk of requiring ICU admission (p<0.001). There were no significant differences regarding age, sex, and presence of underlying comorbidities. Evolution to ARDS was found in eight cases that necessitated ICU care. All of them had on the initial radiograph patchy multifocal consolidations (p<0.001) with bilateral lesions in six cases. A higher number of lung zones involved and consolidation on the initial chest radiograph as well as a rapid progression of the radiological abnormalities were identified in patients requiring ICU admission and development of ARDS. Initial chest radiographs show acute abnormalities in all patients with severe disease. The findings of a multifocal patchy consolidation pattern with bilateral or diffuse lung involvement on admission should alert of the impending severity of disease and the risk of necessitating ICU admission.

‘Presenting CXR phenotype of H1N1’ flu compared with contemporaneous non-H1N1, community acquired pneumonia, during pandemic and post-pandemic outbreaks’

“…Two small studies of patients admitted to the ITU demonstrated that bilateral and multi-focal changes on the presenting chest X-ray, was more likely to require ITU admission and progression to an ARDS type appearance [7,8]. In our study, the length of inpatient hospital stay was longer in the H1N1 cohort, compared with non-H1N1, although this did not quite reach statistical significance.…”

“…Several studies have reported on the chest X-ray phenotype, some suggesting prognostication of H1N1 disease by chest Xray appearance and further studies of serial imaging, which have demonstrated lung infiltration and progression to acute respiratory distress syndrome (ARDS) [6][7][8]. However, at the point of presentation, it would be necessary to identify H1N1 rapidly and differentiate it from the less aggressive community acquired pneumonias.…”

“…A number of studies looking at clinical risk factors identified an association between an abnormal chest X-ray and adverse outcome [3,7,8,21]. Two small studies of patients admitted to the ITU demonstrated that bilateral and multi-focal changes on the presenting chest X-ray, was more likely to require ITU admission and progression to an ARDS type appearance [7,8].…”

General Characteristics and Prognostic Factors of Pneumonia Cases DevelopedDuringPandemic(H1N1)Influenza-AVirus InfectioninTurkey

“…According to the literature, some patients may have a normal chest radiograph at first presentation, but may develop alveolar opacities and bilateral interstitial infiltrates on chest radiographs in the following days (12,21). It was reported that radiological findings were more often bilateral in patients who underwent mechanical ventilation due to severe respiratory failure (4,21,22). Even where no radiological evidence of disease is initially detected, radiological findings may subsequently emerge and serious respiratory failure may develop over a short period.…”

Chest Imaging Findings in Hospitalized Children with H1N1 Influenza

“…A rapid progression of the radiological abnormalities and development of acute respiratory distress syndrome (ARDS) can be identified in patients requiring PICU admission (15,26). In one of our patients, while the X-ray was normal at admission, bilateral patchy opacities at basal regions appeared in the thorax CT scan after 4 h of admission, and ARDS developed after 18 h of admission.…”