Bronchiolitis / RSV

Bronchiolitis is a lower respiratory tract infection that primarily affects infants under 12 months, peaking at 2–6 months of age. Respiratory syncytial virus (RSV) causes the majority of cases. The virus triggers inflammation and edema of the small bronchioles, producing mucus plugging that traps air and causes wheezing, tachypnea, nasal flaring, and intercostal retractions. It starts as an upper respiratory infection — rhinorrhea, low-grade fever, cough — then progresses over 2–3 days to increased work of breathing. The hallmark assessment finding is diffuse expiratory wheezing with fine crackles on auscultation in an infant with a preceding URI. Diagnosis is clinical, though a nasal swab for RSV antigen confirms the virus. Oxygen saturation persistently below 90% warrants supplemental O₂. Treatment is primarily supportive: hydration (small frequent feedings or IV fluids if tachypneic), nasal suctioning (bulb or deep), humidified oxygen, and frequent reassessment. Bronchodilators and corticosteroids are generally NOT recommended — this is inflammation-driven mucus plugging, not bronchospasm. Palivizumab (Synagis) is a monoclonal antibody given monthly during RSV season for prophylaxis in high-risk infants (premature, with congenital heart disease, or chronic lung disease). Contact and droplet precautions are essential — RSV survives on surfaces for hours and spreads rapidly through pediatric units.