School of Biomedical Engineering, Capital Medical University, 10 Xitoutiao, Youanmenwai, Beijing, 100069, China.
Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, China.
Sleep Breath. 2020 Dec;24(4):1623-1631. doi: 10.1007/s11325-020-02044-x. Epub 2020 Mar 13.
Studies reveal that rostral fluid shifts due to body posture changes from standing to lying down may narrow the upper airway. However, without credible and direct experimental evidence, it remains unclear what the role of natural fluid redistribution in the neck is in affecting obstructive sleep apnea (OSA) severity. Our aim is using direct experimental evidence to determine whether or not postural fluid shifts affect OSA severity.
We performed overnight polysomnography on two consecutive nights for 22 men. The bed was set horizontally on the control night, while its tail part was lowered by 30° on the experimental night to reduce the amount of fluid shifted into the neck. We measured sleep and anthropometric parameters on each night.
The mean (95% CI) apnea-hypopnea index (AHI) in the supine head and trunk position decreased from 66.6 events per hour (57.6-75.6) to 61.2 (52.0-70.4) (t = 4.507, p <0.001), and the oxygen desaturation index from 69.5 events per hour (56.4-82.6) to 61.6 (50.5-72.6) (t = 3.293, p = 0.004), from the control to the experimental night with a decrease in the change of leg fluid volume from 17.7% (15.7-19.8) to 4.7% (1.9-7.5) (t = 11.659, p < 0.001).
Our findings provide direct experimental evidence to show that natural fluid shift caused by the day-to-night posture change does contribute to OSA pathogenesis and severity. It is likely that the neck fluid increase from an actual day-to-night position change, with 90° change in posture, would produce a much larger AHI increase than the 11.2% found in this study, which contains only a 30° change in posture. These findings suggest that reducing the amount of fluid in the neck region may relieve airway obstructions for patients with moderate and severe OSA.
研究表明，体位从站立变为躺下时的头侧液流转移可能会使上气道变窄。然而，由于缺乏可靠和直接的实验证据，目前尚不清楚颈部自然液体再分配在影响阻塞性睡眠呼吸暂停（OSA）严重程度方面的作用是什么。我们的目的是利用直接的实验证据来确定体位液流转移是否会影响 OSA 的严重程度。
我们对 22 名男性进行了连续两个晚上的整夜多导睡眠图检查。在对照晚上，将床水平放置，而在实验晚上，将床尾部分降低 30°，以减少流入颈部的液体量。我们在每个晚上测量睡眠和人体测量参数。
仰卧位头部和躯干位置的平均（95%置信区间）呼吸暂停低通气指数（AHI）从每小时 66.6 次（57.6-75.6）降至 61.2（52.0-70.4）（t=4.507，p<0.001），氧减指数从每小时 69.5 次（56.4-82.6）降至 61.6（50.5-72.6）（t=3.293，p=0.004），从对照夜到实验夜，腿部液体量的变化从 17.7%（15.7-19.8）降至 4.7%（1.9-7.5）（t=11.659，p<0.001）。
我们的研究结果提供了直接的实验证据，表明由昼夜体位变化引起的自然液体转移确实有助于 OSA 的发病机制和严重程度。很可能是由于实际的昼夜体位变化导致颈部液体增加，体位变化 90°，比本研究中发现的 11.2%的 AHI 增加更大，本研究仅包含 30°的体位变化。这些发现表明，减少颈部区域的液体量可能会缓解中重度 OSA 患者的气道阻塞。
