Chapter 48: Bronchiolitis

Patient Story

A 5-month-old full-term female infant presents to your office with 3 days of fever and cough. On examination, you note a frequent wet cough and appreciate bilateral wheezes. Pulse oximetry reveals a normal oxygen saturation. You reassure the mom that her daughter has bronchiolitis and needs supportive care only (Figure 48-1). She agrees to follow up with you in 1 to 2 days.

Introduction

Bronchiolitis is inflammation of the bronchioles typically caused by a viral illness that frequently affects young children.¹

Synonyms

Respiratory Syncytial Virus (RSV) or lower respiratory tract infection (LRTI).

Epidemiology

• Most common lower respiratory tract infection in children less than 1 year of age.¹

• Annual hospitalizations for bronchiolitis account for greater than half a billion dollars in health care expenditures.²

Etiology and Pathophysiology

• Viral etiology, most frequently RSV.

• Other viruses implicated include influenza, parainfluenza, adenovirus, and human metapneumovirus.

• Inflammation, edema, and necrosis of epithelial cells lining bronchioles (Figure 48-1).

• Leads to increased mucus production and bronchospasm.

Risk Factors

• Up to 90 percent of infants will have had an RSV infection by the age of 2 years.¹

• Infants with exposure to child care center populations, school-aged siblings, and smoke are at higher risk for developing bronchiolitis.³

• Risk factors for severe disease include:

  • Prematurity of less than 35 weeks gestation.

  • Chronic lung disease or congenital airway malformations.

  • Cyanotic congenital heart disease.

  • Severe neuromuscular disease.

  • Immunocompromised state.⁴

Diagnosis

Clinical Features

• Bronchiolitis is a clinical diagnosis.

• Signs and symptoms include rhinorrhea, cough, tachypnea, bilateral wheezing, and signs of increased work of breathing such as use of accessory muscles and/or nasal flaring.

Laboratory Testing

• Laboratory testing is not routinely indicated.

• Respiratory viral testing can be obtained if necessary for epidemiologic surveillance and research but the results do not change the management of the disease.

Imaging

• As most chest x-rays obtained in patients with bronchiolitis are found to be normal, routine chest radiography is not recommended for patients with bronchiolitis (Figure 48-2).

• Nonspecific findings such as hyperinflation, perihilar markings, or central bronchial thickening can be seen in some patients (Figure 48-3 to 48-5).

• Chest radiography may be necessary if the patient experiences a severe course or does not improve as expected based on the natural history of disease.