Upper Airway Dilator Muscle Activity During Sleep Onset.

睡眠时呼吸紊乱被认为是一个主要的健康问题。其中，阻塞性睡眠呼吸暂停是最普遍的，大约有4%的男性和2%的女性患有此病。在这种疾病中，上呼吸道在睡眠期间塌陷，导致气流停止和随后的氧饱和度下降。气道被认为是闭塞的，因为面对由吸气力产生的负压，扩张肌不能维持通畅。为了重新建立气道通畅，必须从睡眠中产生某种形式的唤醒。由于UA很可能在恢复睡眠时崩溃，循环变得重复，导致严重的睡眠中断。呼吸暂停综合症是一种重大的健康风险，与心血管疾病风险增加、死亡率增加、白天过度嗜睡、白天表现下降和事故风险增加有关。在之前的工作中，我们已经证明了正常睡眠中与上呼吸道扩张肌活动相关的变化会导致睡眠开始时气道口径的减少。这使一些人，比如那些呼吸道狭窄的人，在睡眠时呼吸道阻塞。我们还报道了老年男性在睡眠时上呼吸道肌肉活动的减少比年轻男性更大，这表明他们可能有更高的阻塞性睡眠呼吸暂停患病率的一个原因。本项目的目的是确定老年男性上呼吸道肌肉活动减少幅度较大的原因。这个问题的答案将有助于理解为什么这个群体如此容易受到阻塞性睡眠呼吸暂停的影响，并将阐明导致这种疾病的机制。

Disorders of breathing during sleep are recognised as a major health problem. Of these, Obstructive Sleep Apnoea is the most prevalent, occurring in approximately 4% of the male and 2% of the female population. In this disorder the upper airway collapses during sleep causing cessation of airflow and subsequent oxygen desaturation. The airway is thought to occlude because dilator muscles are unable to sustain patency in the face of the negative pressures generated by inspiratory effort. In order for patency of the airway to be re-established some form of arousal from sleep must occur . As the UA is likely to collapse on the resumption of sleep, the cycle becomes repetitive, causing significant sleep disruption. OSA is a significant health risk, being associated with increased risk of cardiovascular disorders, increased mortality, excessive daytime sleepiness, reduced daytime performance and increased risk of accidents. In previous work we have demonstrated that normal sleep related changes in the activity of upper airway dilator muscles result in a reduction in the calibre of the airway at sleep onset. This exposes some individuals, such as those with narrow airways, to airway obstruction during sleep. We have also reported that elderly men have larger reductions in upper airway muscle activity at sleep onset than younger men, suggesting one reason why they may have a higher prevalence for Obstructive Sleep Apnea. The aim of the present project is to determine what causes the larger reductions in upper airway muscle activity in older males. The answer to this question will contribute to understanding why this group is so susceptible to Obstructive Sleep Apnea and will elucidate the mechanisms leading to the disorder.