Bronchiolitis: Clinical sciences

Bronchiolitis refers to a viral infection of the lower respiratory tract that primarily affects the bronchioles, and causes airway inflammation and obstruction. This is most often caused by respiratory syncytial virus, or RSV for short, but can also be caused by other viruses, including human metapneumovirus and parainfluenza. Bronchiolitis primarily affects children under 2 years of age, most often during fall and winter months, and it’s typically mild and self-limited, but infants with certain risk factors can develop severe respiratory distress. As far as the treatment goes, bronchiolitis can be managed in the outpatient or hospital setting.

If your patient presents with a chief concern suggesting bronchiolitis, first perform an ABCDE assessment to determine if your patient is unstable or stable. If unstable, stabilize their airway, breathing, and circulation. Additionally, obtain IV access and put your patient on continuous vital sign monitoring, including respiratory rate, pulse oximetry, and cardiac monitoring. Finally, if needed, don’t forget to provide supplemental oxygen.

Now, let’s go back to the ABCDE assessment and take a look at stable patients. In this case, you should first obtain a focused history and physical exam. Your patient is likely to be under 2 years of age; with a history of illness that started with milder symptoms, such as fever and rhinorrhea for the first three days, followed by worsening of symptoms like respiratory distress. It’s important to note that a young infant under 2 months of age could present with apnea as their first sign, in the absence of any other symptoms!

Physical exam typically reveals labored breathing, tachypnea, and hypoxia. You may detect nasal flaring or grunting, as well as abdominal breathing or suprasternal, intercostal, and subcostal retractions; while auscultatory findings may include wheezing, crackles, and a prolonged expiratory phase. Infants with poor oral intake may have signs of dehydration, like a sunken fontanelle and poor skin turgor. The presence of these findings should make you suspect bronchiolitis, which is usually a clinical diagnosis based on the presence of classic history and physical exam findings.

Here’s a clinical pearl to keep in mind! While radiographs and viral testing are generally not recommended in the evaluation of bronchiolitis, their use can be considered when the diagnosis is not straightforward, or if a different condition is suspected. The chest radiograph of a child with bronchiolitis typically demonstrates hyperinflation and peribronchial thickening in the perihilar region, and may even include areas of increased density due to local atelectasis. These findings might be falsely interpreted as bacterial pneumonia, leading to unnecessary antibiotic use. In addition, routine viral testing does not typically change clinical decision-making, although it can be helpful when other respiratory viruses like influenza are circulating in the community. PCR results should be interpreted cautiously, as they may detect prolonged viral shedding from an unrelated previous illness, particularly with rhinovirus. On the other hand, RSV detected by PCR is almost always associated with bronchiolitis.

Alright, once you diagnose bronchiolitis, you’ll need to assess the criteria for hospitalization in order to determine a treatment plan. These criteria include poor oral intake, apnea, an oxygen saturation below 90%; respiratory rate above 70 breaths per minute if your patient is less than 2 months of age, but above 60 if they’re 2 to 12 months old, and above 50 if they’re 12 to 24 months old; heart rate above 160 beats per minute; and risk factors for severe disease, including prematurity, chronic lung or heart disease, immunocompromised state, or a neuromuscular disorder. Lastly, if a caretaker is unable to provide adequate care at home, hospitalization can be considered.

If none of these criteria for hospitalization are met, then your patient can be managed as an outpatient. Treatment of bronchiolitis primarily relies on supportive care, so instruct caretakers to use nasal suctioning, as needed, and ensure that oral intake remains adequate. Be sure to counsel the caretaker to monitor for worsening symptoms.

On the other hand, if one or more of the criteria for hospitalization are met, then admit your patient to the hospital for inpatient management. Begin medical management, which includes respiratory monitoring with supplemental oxygen if your patient’s oxygen saturation goes below 90%. You can also consider administering nebulized hypertonic saline to improve mucus clearance, but keep in mind that beta-agonists, racemic epinephrine, and systemic corticosteroids have not been shown to be helpful in bronchiolitis, and their routine use isn’t recommended.