An 8-week-old male infant was brought to the ED by his parents after an episode in which it appeared the baby had stopped breathing. The parents stated that while lying on his mother’s lap at home, the patient stopped breathing for approximately 10 to 15 seconds, during which time his face exhibited a bluish color. They further noted that the patient began breathing again after gentle stimulation and had been acting normally since.
The patient was born at 39 weeks gestation via normal vaginal delivery and without any complications. His parents further stated that prior to the cessation of breathing incident, his symptoms of nasal congestion, decreased energy level, and fast breathing had gradually worsened over the past 2 days. The parents also noted that the infant had not been feeding as well over the past 2 days.
Upon arrival, the patient’s vital signs were: heart rate, 140 beats/minute; respiratory rate (RR), 72 beats/minute; and temperature 101.3°F. Oxygen saturation was 92% on room air. On physical examination, the infant had significant rhinorrhea, moderate intercostal and supraclavicular retractions, ausculatory wheezes, and transmitted upper airway noises throughout.
Bronchiolitis, a disorder caused by a viral lower respiratory tract infection, is the most common lower respiratory infection in children younger than age 2 years.1 In 2014, the American Academy of Pediatrics (AAP) characterized bronchiolitis as “rhinitis, cough, tachypnea, wheezing, rales, use of accessory muscles, and/or nasal flaring in children under 24 months of age.”2 This condition is the most common cause of hospitalization in the first 12 months of life. It is responsible for over 100,000 admissions annually at an estimated cost to the healthcare system of $1.73 billion.3
Etiology and Pathophysiology
Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis. In the United States, the highest incidence of infection occurs during the months of December through March, with some degree of regional variability.4 A number of other viruses that can cause bronchiolitis include human metapneumovirus, parainfluenza virus, and influenza virus.1 Infection with RSV does not grant permanent immunity, and reinfection is common throughout life.2
Pathophysiologically, bronchiolitis is characterized by an invasion of bronchial epithelial cells that lead to to cell death and sloughing into the bronchial lumen. This, coupled with increased mucous production and submucosal edema, leads to a narrowing of the bronchial lumen and obstruction of airflow.5
Bronchiolitis represents a constellation of signs and symptoms beginning with those of an upper respiratory tract infection, including nasal congestion and rhinorrhea with mild cough. On days 3 to 5, the following symptoms develop: tachypnea, wheezing, rales, and signs of respiratory distress (eg, grunting, nasal flaring, inter-/subcostal retractions). Approximately two-thirds of patients will develop a fever.2 Recovery tends to begin around days 5 to 7, with the median duration of illness being 12 days.1 It should be noted that bronchiolitis represents a highly variable and dynamic disease state. Transient episodes of improvement and worsening are common, emphasizing the importance of serial examinations and assessments. Though rare, progression to respiratory failure and death do occur.2
History and Risk Stratification
The focus of the initial history by the clinician should serve two primary purposes. First, it is important to differentiate infants with probable bronchiolitis from those with other disease states having similar clinical manifestations. One of the most challenging diseases to differentiate from bronchiolitis is that of reactive airway disease (RAD). Eliciting a history of allergic rhinitis, eczema, or a family history of asthma may be helpful in determining the precise etiology of the patient’s symptoms. Although no longer recommended for children with bronchiolitis (as will be later discussed), a trial of a bronchodilation may be beneficial in the setting of familial atopy.
The second—and perhaps most important—aspect of patient history is to determine the presence of risk factors for both apnea and the development of severe bronchiolitis. Regarding the risk factors for apnea, Willwerth et al6 developed a set of criteria to identify patients at high risk for apnea in the inpatient setting. Patients were considered high risk if they were born at full term and were younger than 1 month of age; if they were born preterm (<37 weeks gestation) and were younger than 48 weeks postconception; and/or if the infant’s parents or a clinician had already witnessed an episode of apnea during the patient’s illness. In this study, all patients who developed apnea were correctly identified by the risk criteria.6 Risk factors for severe bronchiolitis include the following: patient age younger than 12 weeks; patient prematurity younger than 37 weeks gestation; and an underlying hemodynamically significant congenital heart disease, chronic lung disease/bronchopulmonary dysplasia, or an immunocompromised state.1