Asthma and Obstructive Sleep Apnea.
OBJECTIVE
To get a comprehensive understanding about the relationship between obstructive sleep apnea (OSA) and asthma by reviewing the epidemiology, pathophysiology, and clinical manifestation and then summarizing the latest progress on diagnosis and treatment.


METHODS
Articles referred in this review were mainly collected from a comprehensive search of the PubMed published in English from 1990 to 2015 with the terms "OSA" and "asthma" as the main keywords. Highly regarded older publications were also included.


METHODS
Information about the features of the two diseases in common, the pathophysiologic association between them and their current treatments from the literature search were identified, retrieved, and summarized.


RESULTS
Both OSA and asthma are very prevalent conditions. The incidences of them have kept on rising in recent years. Asthma is often accompanied by snoring and apnea, and OSA often combines with asthma, as well. They have many predisposing and aggravating factors in common. Possible shared direct mechanistic links between them include mechanical effects, intermittent hypoxia, nerve reflex, inflammation, leptin, etc. Indirect mechanistic links include medication, nose diseases, smoking, obesity, and gastroesophageal reflux disease. Since OSA presents many similar features with nocturnal asthma, some scholars termed them as a sole syndrome - "alternative overlap syndrome," and proved that asthma symptoms in those patients could be improved through the treatment of continuous positive airway pressure.


CONCLUSIONS
OSA and asthma are closely associated in pathogenesis, symptoms, and therapies. With the growing awareness of the relationship between them, we should raise our vigilance on the coexistence of OSA in those difficult-to-control asthmatic patients. Further studies are still needed to guide the clinical works.
Yi-Xian
YX
Qiao
Department of Respiratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
Yi
Y
Xiao
D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000503:physiopathology