Croup in children.

adian children each year, making it the second most common cause of respiratory distress in the first decade of life. It affects boys more than girls (1.4:1) and young children between 6 months and 3 years of age more commonly than younger infants, older children and adolescents. Croup is frequently preceded by 24–72 hours of nonspecific cough, rhinorrhea, coryza and fever, with abrupt onset of barky cough, hoarse voice and, often, inspiratory stridor during the night. Croup is caused by a viral infection of the respiratory tract that causes edema and in flam ma tion of the upper airway, and laryngeal mucosa resulting in narrowing in the subglottic region of the airway. Human parainfluenza virus (types 1 and 3) is the most common pathogen, but other causative vi ruses include influenza A and B viruses, respi ra tory syncytial virus, rhino virus, coronavirus, human metapneumovirus and ad e no vi rus. Predictable seasonal patterns occur; the peak incidence of croup typically ap pears in late fall. Annual patterns are also found, with about 50% more cases occurring in oddnumbered years, correlating with prevalence of parainfluenza viruses in the community. Croup symptoms are most often worse at night and can fluctuate rapidly depending on whether the child is calm or agitated. Typically, symptoms are short-lived, with about 60% of children having resolution of the barky cough by 48 hours and less than 2% having symptoms persisting for longer than 5 nights. Based on a review of utilization data from pediatric and general emergency departments in Alberta, at least two-thirds of children with croup have mild symptoms on presentation (personal observation). Population-based data indicate that 1%– 5% of children with croup are admitted to hos pital, and, of those admitted, less than 3% receive intubation. Death ap pears to be rare; based on a combination of data from several reports, we estimate death occurs in no more than 1 in 30 000 cases. This review will address the diagnosis and management of croup in children, specifically focusing on clinical assessment of disease severity to guide management decisions. The recommendations in this review are based primarily on robust systematic reviews and randomized controlled trials, as well as the clinical practice guideline for croup that was developed by the Toward Optimized Practice Program.17 Box 117–20 outlines the evidence used in this review.