Bronchiolitis is an inflammation of the bronchioles, often seen in young children with viral respiratory infections. Although the most common radiographic finding of bronchiolitis is a normal chest radiograph, patients may also present with pulmonary hyperinflation, peribronchial thickening, and discoid atelectasis. Care should be made not to mistake an underinflation artifact with peribronchial thickening related to bronchiolitis. Alternatively, when the heart is enlarged, care should be made not to confuse pulmonary vascular congestion related to congenital heart disease with peribronchial thickening related to bronchiolitis. The utility of the chest radiograph in the evaluation of bronchiolitis is to rule out related complicating features, including superimposed pneumonia, atelectasis, and pneumothorax/pneumomediastinum. Chest x-ray may also help to rule out other causes of wheezing such as a foreign body aspiration.
Bronchiolitis patients are often neonates to 2-year-olds and present with tachypnea, wheezing, hypoxia, copious rhinorrhea, and in more severe cases respiratory distress. Common pathogens of bronchiolitis include respiratory syncitial virus (RSV), influenza, parainfluenza, human metapneumovirus, and many other viruses. Patients who are less than one month old, born prematurely and are less than 48 weeks post-conceptual age, and those with co-morbid conditions are at risk of developing apnea. Days 3-5 are usually the most severe of the illness in regards to respiratory distress. Dehydration is a common finding in this time period as younger patients have difficulty swallowing when their respiratory rates get above 60. Treatment of bronchiolitis is ever changing but beta agonist and steroids have generally not been shown to be helpful. Criteria for discharge should include adequate hydration status, oxygenation saturations above 90%, and close follow-up within 24 hours.
The chest radiograph is primarily used in bronchiolitis to rule out complicating factors such as foreign body aspiration and pneumonia.
Consideration should be given to whether the patient could have congenital heart disease when there is an enlarged cardiac silhouette on chest radiograph.
Figure 12.1 ▪ Peribronchial Thickening.
AP chest radiograph of bronchiolitis in a 3-year-old girl demonstrates diffuse bilateral peribronchial thickening and patchy and discoid atelectasis. Hyperinflation is present.
Figure 12.2 ▪ Discoid Atelectasis.
AP chest radiograph of bronchiolitis in a 2-year-old boy demonstrates bilateral multifocal discoid atelectasis (arrows).
Figure 12.3 ▪ Underinflaction Artifact.
PA chest radiograph in a 6-year-old girl with a normal chest radiograph with underinflation artifact. Care should be taken not to confuse underinflation artifact for peribronchial thickening related to bronchiolitis.
Figure 12.4 ▪ Right Lower Lobe Pneumonia.