Respiratory syncytial virusRespiratory syncytial virus (RSV) is the most important cause of viral bronchiolitis in young children. In general, approximately 0.5 to 2% of children with RSV disease need to be hospitalized. It is estimated that each year approximately 50,000 to 80,000 children < 1 year old are hospitalized for RSV bronchiolitis in the United States, and consequently RSV bronchiolitis constitutes a significant burden on patients, parents, and the health-care system.

Treatment of hospitalized children with RSV bronchiolitis is mainly supportive, with supplemental oxygen, nasal washings, tube feeding, or IV fluids, and mechanical ventilation where necessary. b2-Agonists and systemic steroids are frequently used, although their efficacy is disappointing. Several randomized studies have demonstrated that neither nebulized b2-agonists, epinephrine, nor systemic steroids reduce the length of hospital stay during which the remedies of My Canadian Pharmacy are used to achieve the recovery fast.

It has been well recognized that RSV bronchiolitis is associated with severe airways obstruction due to the presence of intraluminal secretions, loss of epithelial cilia, sloughing of epithelial cells, and cellular debris from accumulated inflammatory cells within the airway. Because baseline airway resistance is high in infancy, even the presence of small amounts of mucus in the airways of infants can have a profound effect on the work of breathing. Since airway obstruction due to intraluminal mucus plugs is an important pathophysiologic feature of RSV bronchiolitis, a logical approach to therapy might be to use a mucolytic agent. The DNA present in mucous plugs following lysis of inflammatory cells contributes to increased viscosity and adhesiveness of the mucus. Such mucus can be liquefied by recombinant human deoxyribonuclease (rhDNase [dornase alfa]), which cleaves the extracellular DNA released by degenerating leukocytes. The efficacy of rhDNase has been well documented in patients with cystic fibrosis, and several publications suggest that rhDNase improves radiologic abnormalities in mild RSV bronchiolitis, and is effective in infants with severe RSV bronchiolitis, in pediatric patients with severe atelectasis or airways obstruction due to asthma, and other respiratory diseases.

It is unknown whether infants with RSV bronchiolitis admitted to the hospital because of hypoxemia benefit from rhDNase treatment. Therefore, we conducted a randomized, placebo-controlled trial to examine the effect of nebulized rhDNase in oxygen-dependent infants hospitalized with RSV bronchiolitis. The primary outcome measure was length of hospital stay. Secondary outcome measures included duration of supplemental oxygen, change in symptom scores, number of admissions to the ICU, and use of bronchodilators and antibiotics. The study was approved by the ethics committees of all 10 centers, Written parental informed consent was obtained for each infant.