What can we learn from chest radiographs in hypoxemic asthmatics?

Background: Chest radiographs (X-rays) are frequently obtained on children with asthma exacerbations who remain hypoxemic after therapy even though their utility has not been evaluated. Objective: To compare X-rays in hypoxemic and non-hypoxemic asthmatic children. Methods: Over 21 months, X-rays were obtained on all persistently hypoxemic asthmatics (1-17 years, oxygen saturation ≤ 93% in room air), and some non-hypoxemic asthmatics. A pediatric radiologist blinded to the patients' symptoms evaluated each X-ray for lung size, extravascular lung fluid, and atelectasis. Clinical outcomes including duration of hypoxemia, length of hospital stay, and admission to the PICU were assessed through chart audit after hospital discharge. Results: A total of 445 patients were enrolled and stratified into four groups based on initial and post-treatment pulse oximetry measurements. Hypoxemic groups I and II were more likely to have large or small lungs (P < 0.05), severe interstitial fluid (P < 0.01), and atelectasis (P < 0.01) compared to non-hypoxemic group IV. Group I was more likely to have fluid in the alveolar space compared to all other groups (P < 0.01). Within hypoxemic group I, there was no association between any radiographic findings and our clinical outcomes. Conclusion: Large or small lung sizes, extravascular fluid, and atelectasis were more common in the X-rays of hypoxemic asthmatics.