Candice Leigh Bjornson, MD,* and David W. Johnson, MDy
Key Words: Croup, epidemiology, diagnosis, epinephrine, corticosteroids
Physicians, resident physicians, medical students, nurse practitioners, and physician assistants who assess and treat children with croup. Pediatric emergency physicians, pediatricians, and familyphysicians will find the information contained in this comprehensive review especially useful.
After completion of this article, the reader will be able to: 1. Discuss the epidemiology of croup in the pediatric population. 2. Identify the common etiological agents for croup, and describe the pathophysiology resulting in typical symptoms of croup. 3. Recognize clinical features thatsupport alternate diagnoses and the potential complications of croup. 4. Describe 4 levels of clinical severity of croup. 5. Discuss the role of laboratory and radiological investigations in a child with croup. 6. Know the indications for hospital admission in a child with croup. 7. Discuss the role of nonpharmaceutical interventions in a child with croup (mist, oxygen). 8. Discuss the role ofepinephrine and corticosteroids in a child with croup.
3% of children younger than 6 years annually.1 The clinical picture is characterized by the abrupt onset of a distinctive barky cough, which may be accompanied by stridor, hoarse voice, and respiratory distress. Croup symptoms are often preceded by nonspecific symptoms of cough, rhinorrhea, and fever. Croup is most common in children betweenthe ages of 6 months and 3 years, with a peak annual incidence in the second year of life of nearly 5%.1 However, croup occurs in children of all ages, including adolescents,1 and rarely in adults.2 Boys are affected more often than girls, with an overall male to female preponderance of 1.4:1.1 In North America, the peak season for croup is late autumn, but cases are recognized year-round, evenduring the summer.1 In oddnumbered years, the number of children presenting during the peak season is approximately 50% more than during even-numbered years.3 Symptoms are almost always worse at night and can fluctuate in severity depending on whether the child is agitated or calm. Usually, croup symptoms show improvement during the day, but may recur on the following evening.4 Croup symptoms aregenerally short-lived, with approximately 60% of children having resolution within 48 hours. However, a small proportion has symptoms that may continue for up to 1 week.4 Hospitalization of children with croup is uncommon, with fewer than 5% admitted.5 – 7 Furthermore, of those children hospitalized, intubation is rare, on the order of 1% to 3%,8 – 11 and mortality is extremely rare.8 – 13PATHOPHYSIOLOGY
The characteristic symptoms of croup are due to upper airway obstruction resulting from an acute upper airway infection. Infection leads to inflammation and edema of the laryngeal mucosa, followed by epithelial necrosis and shedding.14,15 Resultant narrowing of the subglottic region results in a barky cough, turbulent airflow and stridor, and chest wall indrawing. Further narrowing canlead to asynchronous chest and abdominal movement, fatigue, and eventually hypoxia, hypercapnia, and respiratory failure.16,17 Croup is caused by a variety of viruses, most commonly parainfluenza types 1 and 3.3 Others implicated include influenza A, influenza B, adenovirus, respiratory syncytial virus, metapneumovirus, and Mycoplasma pneumoniae.1,18,19
Croup(laryngotracheobronchitis) is a common respiratory illness of childhood, estimated to affect approximately
*Clinical Assistant Professor, Alberta Children’s Hospital/University of Calgary, Canada and yAssociate Professor Departments of Pediatrics and Pharmacology and Therapeutics, University of Calgary, Faculty of Medicine, Alberta Children’s Hospital, Canada. Drs. Bjornson and Johnson have disclosed that they have...