Ludwig Engel Centre for Respiratory Research, The Westmead Institute for Medical Research, The University of Sydney, Sydney, New South Wales, Australia;
Department of Respiratory and Sleep Medicine, Westmead Hospital, Sydney, New South Wales, Australia; and.
J Appl Physiol (1985). 2017 Nov 1;123(5):1118-1125. doi: 10.1152/japplphysiol.00378.2017. Epub 2017 Aug 17.
Negative effort dependence (NED), decreased airflow despite increased driving pressure, has been proposed as a specific obstructive sleep apnea (OSA) phenotypic characteristic. We examined conditions under which NED occurs in a collapsible tube, pharyngeal airway bench model with the chamber enclosed, focusing on relationships with surrounding pressure levels and longitudinal strain. Using a vacuum source, graded airflows (V̇; 0-5 l/s) were generated through a thin-walled latex tube enclosed within a rigid, cylindrical chamber, sealed with initial chamber pressures (Pci) of 0-5 cmHO (separate runs), or opened to the atmosphere. Upstream minus downstream pressure (Pu - Pd), maximum airflow (V̇), and chamber pressure (Pc) were measured at 0-50% longitudinal strain. NED occurred across the range of Pci and strains studied but was most pronounced for the chamber open condition. With a sealed chamber, V̇ increased and Pc decreased with increasing Pu - Pd until the onset of NED at V̇ and a Pc value that was designated as critical (Pcc). Pcc was lowest (-17 cmH0) and V̇ was highest (~5 l/s) with chamber sealed: Pci = 0 cmHO and 12.5 to 25% strain. We conclude that for our collapsible tube model, the achievable V̇ before the onset of NED depends on both the initial conditions (Pci and strain) and the dynamics of feedback between driving pressure and chamber pressure (chamber sealed vs. open). NED-based phenotypic analyses for OSA may need to focus on potential feedback control mechanisms (eg lung volume change, muscle activity) that may link peripharyngeal tissue pressure levels to driving pressures for airflow. A collapsible tube, pharyngeal airway bench model was used to study the role of surrounding pressure and longitudinal wall strain at the onset of negative effort dependence (NED). NED occurred to varying degrees across all conditions tested, but maximum airflow was achieved with ) low initial surrounding pressure, ) a feedback mechanism between surrounding pressure and driving pressure; and ) a moderate amount of strain applied. Potential impacts on OSA phenotypic analyses are discussed.
负努力依赖（NED）是指尽管驱动压增加，但气流仍减少，这被认为是一种特定的阻塞性睡眠呼吸暂停（OSA）表型特征。我们研究了在封闭腔室内的咽气道模型中，在何种条件下会发生 NED，重点关注与周围压力水平和纵向应变的关系。使用真空源，通过一个封闭在刚性圆柱形腔室内的薄壁乳胶管，在不同初始腔室压力（Pci）（单独的运行）或与大气相通的情况下，产生 0-5 l/s 的分级气流（V̇）。在 0-50%的纵向应变下，测量上游与下游压力差（Pu-Pd）、最大气流（V̇）和腔室压力（Pc）。在研究的 Pci 和应变范围内都出现了 NED，但在腔室开放的情况下最为明显。对于封闭腔室，随着 Pu-Pd 的增加，V̇增加，Pc 降低，直到在 V̇和指定为临界值的 Pc 值（Pcc）时发生 NED。当腔室封闭时，Pcc 最低（-17 cmH0）且 V̇最高（~5 l/s）：Pci=0 cmHO 和 12.5 至 25%应变。我们得出结论，对于我们的可折叠管模型，在发生 NED 之前可实现的 V̇取决于初始条件（Pci 和应变）以及驱动压和腔室压之间的反馈动力学（腔室封闭与开放）。针对 OSA 的基于 NED 的表型分析可能需要关注潜在的反馈控制机制（例如肺容积变化、肌肉活动），这些机制可能将咽周组织压力水平与气流的驱动压力联系起来。使用可折叠管咽气道模型研究了在负努力依赖（NED）开始时周围压力和纵向壁应变的作用。在所有测试条件下，NED 都以不同程度发生，但在低初始周围压力、）周围压力和驱动压力之间的反馈机制；以及）适度的应变施加时，实现了最大气流。讨论了对 OSA 表型分析的潜在影响。
