Clinical pulmonary physiology and sleep apnea syndrome

Abstract

Sleep apnea and sleep-related hypoventilation disorders are main diseases in sleep-related breathing disorders (also called as sleep disordered breathing: SDB in Japan). The prevalence of SDB is very high in the former. There are 2 types of sleep apnea; central and obstructive sleep apnea. More than 90% of sleep apnea cases are obstructive sleep apnea (OSA). The prevalence of moderate OSA is high and estimated to be around 20% in males and 10% in post-menopause females. OSA induces intermittent hypoxemia and sleep fragmentation with arousals. Intermittent hypoxemia is supposed to induce oxidative stress, systemic inflammation and increases sympathetic nerve activity, while sleep fragmentation with arousals also induces systemic inflammation and increases sympathetic nerve activity. It is said that three main factors for OSA are obesity, aging and being male, but facial morphology such as micrognathia and retrognathia is a significant factor among East Asian peoples. While it is well known that OSA is a risk factor for hypertension and diabetes, recent reports have shown that hypertension or diabetes is a risk factor for OSA. Thus, the interrelationship between OSA and lifestyle-related diseases is an interesting area for research.