Bronchiolitis is an inflammation of the bronchioles which causes narrowing of the lower respiratory tract and a build-up of mucus. It is a common respiratory condition in infants, with approximately one-third of infants developing bronchiolitis before the age of one. The highest incidence usually occurs between the ages of three to six months.
Bronchiolitis is commonly seen during the winter season, and usually persists for seven to ten days.
Bronchiolitis is generally caused by a viral infection; the majority of cases are caused by respiratory syncytial virus (RSV). Other viruses which may lead to bronchiolitis include parainfluenza virus, rhinovirus, adenovirus, influenza, and human metapneumovirus.
Children may be admitted to hospital with severe bronchiolitis if they have certain risk factors, such as chronic lung disease, congenital heart disease, prematurity, Down Syndrome, or cystic fibrosis. Additionally, younger than three months old and neuromuscular disease also increase the risk.
Typical symptoms of bronchiolitis include persistent cough, wheeze, shortness of breath, fever, runny nose, cold, and the worsening of symptoms during the second or third night of illness.
Other symptoms may include apnoea (in infants younger than six weeks of age), difficulty feeding, and dehydration in severe cases.
Other important areas to cover when taking the history include past medical history, medications/allergies, family history, and social history. Ask about known risk factors, atopic conditions, parental smoking, the child's home situation, and any illness in the family.
Typical Clinical Findings of bronchiolitis include:
Other Clinical Findings can include:
Table 1. Differential diagnoses of bronchiolitis
Differential diagnosisFeatures differentiating from bronchiolitisPneumonia
Viral-induced wheeze
Early-onset asthma
Bordetella pertussis or whooping cough
Gastro-oesophageal reflux
Foreign body aspiration
Bronchiolitis is a condition caused by narrowing of the lower respiratory tract due to inflammation of the bronchioles and build-up of mucus. It is usually caused by a viral infection, with around 80% of cases caused by the respiratory syncytial virus (RSV).
Children are diagnosed clinically with bronchiolitis if they present with coryzal symptoms such as a persistent cough and tachypnoea or chest recession, accompanied by wheeze or crackles heard on chest auscultation. Investigations do not influence the treatment of bronchiolitis.
Bronchiolitis is typically self-limiting, but may require admission to hospital in certain cases. The criteria for admission depends on factors such as apnoea, reduced oxygen saturation, reduced oral intake and presence of risk factors for severe disease. Management is supportive and typically involves oxygen supplementation, positive pressure, nutritional and fluid supplementation, and support for smoking cessation.
Bronchodilators and antibiotics are not effective as the narrowing is due to increased secretions, not bronchoconstriction.
Complications of bronchiolitis can include clinical dehydration, Syndrome of inappropriate antidiuretic hormone (SIADH) and hyponatraemia, and apnoea and respiratory failure requiring intubation and ventilation.
Bronchiolitis is generally self limiting and not all children suffering from it will need to be admitted to a hospital. Supportive management is essential, such as oxygen supplementation, high flow oxygen and treatment of dehydration. Possible complications include: dehydration, SIADH, apnoea and respiratory failure.
Paediatric Emergency Medicine Consultant
