中文摘要：

目的当人体由立姿或坐姿改变为睡眠时的卧姿时,下肢流体会向头颈部迁移,使得上气道变窄。研究体位改变时阻塞性睡眠呼吸暂停（obstructive sleep apnea,OSA）患者头颈部组织中流体重新分布的过程,对于理解流体迁移在OSA患者气道阻塞上扮演的角色具有重要的意义。本研究通过测量OSA重度患者随着体位改变,在不同时刻腿部流体量,以及颈部和腿部几何参量,验证迁移流体量随时间非线性变化的假设。方法对于9名睡眠呼吸暂停低通气指数AHI〉30的重度患者,进行整夜多导睡眠监测,记录睡眠状态及AHI的变化,并测量站立、刚刚仰卧、仰卧15 min,及早上起床前仰卧诸时刻的腿部流体量以及颈围、腿围、踝围等几何参量,分析迁移流体量随时间的变化规律。结果由立姿改为仰卧后,几乎有总迁移量1/5的流体立刻发生迁移;仰卧15 min后迁移量升至1/3。睡眠监测显示受试者进入睡眠时间为（301±183）min。通过数据曲线拟合可推算出,仰卧30 min后流体迁移量将升至总迁移量的1/2。结论在OSA重度患者中,体位改变后,向头颈部迁移的流体量随时间以强非线性规律变化。相比于整夜的流体迁移量,在患者进入睡眠前,主要的流体迁移过程已基本完成。

英文摘要：

ObjectiveWhen the body posture changes from standing or sitting to supine position,thefluid in the lower body will shift into the head and neck,resulting in upper airway narrowing. Investigating theprocess of fluid redistribution in the soft tissues of the head and neck resulting from posture changes is importantfor understanding the role played by fluid shift in airway obstruction in obstructive sleep apnea（OSA） patients.In this study,we measure the leg fluid volume and geometrical parameters of the neck and legs in patients withsevere OSA at different times to test our hypothesis that the amount of fluid shifted into the head and neckchanges nonlinearly with time.MethodsOvernight polysomnography is performed in 9 patients with apnea-hypopnea index AHI 30 to monitor sleep stages and AHIchanges. Neck,calf and ankle circumferences at standing,right after lying down,lying supine for 15 min,and beforerising in the morning are measured to analyze the processof fluid shift with time.ResultsAlmost 20 percent of thetotal amount of displaced fluid shifts immediately after thebody posture changes from standing to supine position.This value increases to one third of the total fluid displacement after lying supine for 15 min. Polysomnographydata show that the time between lying down and sleep onset in OSA subjects is（30 1 ± 18 3） min. We canpredict from data fitting that the amount of fluid shift after lying supine for 30 min may increase to 50% of thetotal amount of displaced fluid.ConclusionsThe amount of fluid shifted into the head and neck changesnonlinearly with time. Compared to the total amount of fluid shift during the whole night,the major process offluid shift has largely finished before sleep onset in these OSA patients.