Risk factors for lung dysfunction
A variety of risk factors are related to impaired lung function in children with OSA.[24,25] However, the independent risk factors for lung function decline in pediatric OSA patients are unknown. We used 12 clinical indicators, including a patient history and lab test results in our risk factor analysis, and found that histories of chronic cough and concomitant asthma were the independent risk factors for lung dysfunction in children with OSA. Asthma and asthma-like symptoms, protracted bronchitis, and upper airway cough syndrome were detected in order of frequency as the reason for chronic cough in children.[26]However, the evidence for pediatric OSA as a cause of chronic cough is still ambiguous. An evaluation of children with chronic cough and obstructive sleep apnea at a single medical center showed that the superposition of both those factors on top of lower airway mucosal inflammation further damages lung function and aggravates the pre-existing airway hyper-responsiveness.[27]Similarly, 31 of the 45 OSA patients with abnormal lung function in our study also had asthma. Although none of those patients had recently had an acute asthma attack, their poor lung function coupled with factors related to surgical stress caused us to believe that sedatives would greatly increase the risk for an acute attack of asthma during the perioperative period.[28,29] Von Ungern-Sternberg et al[30]demonstrated that an increased pediatric anesthetic risk for bronchospasm was closely associated with a positive respiratory history of nocturnal dry cough and wheezing, or a family history of asthma and atopy. In our study, wheezing and a family history of allergic diseases were associated with decreased lung function in the univariate analysis, but were meaningless in the multivariate logistic regression analysis. Wheezing is a common symptom of asthma, and asthma patients often have a family history of allergic diseases.[31] We speculated that the collinearity between wheezing and a family history of allergic diseases or asthma led to that result. Therefore, when children with OSA have these risk factors for lung function decline (e.g., a history of chronic cough or concomitant asthma), special attention should be given to providing them with the follow-up airway intervention to help ensure the safety of surgery.