Wootton David M, Sin Sanghun, Luo Haiyan, Yazdani Alireza, McDonough Joseph M, Wagshul Mark E, Isasi Carmen R, Arens Raanan
Department of Mechanical Engineering, The Cooper Union for the Advancement of Science and Art, New York, New York;
Children's Hospital at Montefiore, New York, New York.
J Appl Physiol (1985). 2016 Oct 1;121(4):925-931. doi: 10.1152/japplphysiol.00190.2016. Epub 2016 Jul 21.
Obstructive sleep apnea syndrome (OSAS) is associated with anatomical abnormalities restricting upper airway size and functional factors decreasing pharyngeal dilator activity in sleep. In this study we hypothesized that OSAS is also associated with altered pharyngeal mechanical compliance during wakefulness. Five OSAS and six control obese girls between 14 and 18 years of age were studied. All underwent polysomnography, critical closing pressure (P) studies, and dynamic MRI of the upper airway during awake tidal breathing. Effective airway compliance was defined as the slope of cross-sectional area vs. average pressure between maximum inspiration and maximum expiration along the pharyngeal airway. Pharyngeal pressure fields were calculated by using image-based computational fluid dynamics and nasal resistance. Spearman correlations were calculated to test associations between apnea-hypopnea index (AHI), P, and airway compliance. Effective compliances in the nasopharynx (C) and velopharynx (C) were lower and negative in OSAS compared with controls: -4.4 vs. 1.9 (mm/cmHO, P = 0.012) and -2.1 vs. 3.9 (mm/cmHO, P = 0.021), respectively, suggesting a strong phasic pharyngeal dilator activity during inspiration in OSAS compared with controls. For all subjects, C and AHI correlated negatively (r = -0.69, P = 0.02), and passive P correlated with C (r = -0.76, P = 0.006) and with AHI (r = 0.86, P = 0.0006). Pharyngeal mechanics obtained during wakefulness could be used to characterize subjects with OSAS. Moreover, negative effective compliance during wakefulness and its correlation to AHI and P suggest that phasic dilator activity of the upper pharynx compensates for negative pressure loads in these subjects.
阻塞性睡眠呼吸暂停综合征（OSAS）与限制上气道大小的解剖学异常以及降低睡眠时咽部扩张肌活动的功能因素有关。在本研究中，我们假设OSAS还与清醒状态下咽部机械顺应性改变有关。对5名14至18岁的OSAS肥胖女孩和6名对照肥胖女孩进行了研究。所有受试者均接受了多导睡眠图检查、临界闭合压（P）研究以及清醒潮气呼吸时上气道的动态磁共振成像。有效气道顺应性定义为沿咽部气道在最大吸气和最大呼气之间横截面积与平均压力的斜率。通过基于图像的计算流体动力学和鼻阻力计算咽部压力场。计算Spearman相关性以测试呼吸暂停低通气指数（AHI）、P和气道顺应性之间的关联。与对照组相比，OSAS患者鼻咽部（C）和腭咽部（C）的有效顺应性较低且为负值：分别为-4.4对1.9（mm/cmHO，P = 0.012）和-2.1对3.9（mm/cmHO，P = 0.021），这表明与对照组相比，OSAS患者在吸气时咽部扩张肌活动较强。对于所有受试者，C与AHI呈负相关（r = -0.69，P = 0.02），被动P与C相关（r = -0.76，P = 0.006）且与AHI相关（r = 0.86，P = 0.0006）。清醒状态下获得的咽部力学特性可用于对OSAS患者进行特征描述。此外，清醒时的负有效顺应性及其与AHI和P的相关性表明，上咽部的阶段性扩张肌活动可补偿这些患者的负压负荷。
