Centre Explor, Air Liquide Healthcare, Gentilly, France.
Unit of Biophysics and Bioengineering, Faculty of Medicine and Health Sciences, University of Barcelona-Institut Investigacions Biomediques August Pi Sunyer , Barcelona , Spain.
J Appl Physiol (1985). 2018 Aug 1;125(2):605-614. doi: 10.1152/japplphysiol.00877.2017. Epub 2018 Apr 19.
The upper airway (UA) in humans is commonly modeled as a Starling resistor. However, negative effort dependence (NED) observed in some patients with obstructive sleep apnea (OSA) contradicts predictions based on the Starling resistor model in which inspiratory flow is independent of inspiratory driving pressure when flow is limited. In a respiratory bench model consisting of a collapsible tube and an active lung model (ASL5000), inspiratory flow characteristics were investigated in relation to upstream, downstream, and extra-luminal pressures (denoted as P, P, and P, respectively) by varying inspiratory effort (muscle pressure) from -1 to -20 cmHO in the active lung. P was provided by a constant airway pressure device and varied from 4 to 20 cmHO, and P was set at 10 and 15 cmHO. Upstream resistance at onset of flow limitation and critical transmural pressure (P) corresponding to opening of the UA were found to be independent of P, P, and P. With fixed P, when P fell below a specific value (P'), inspiratory peak flow became constant and independent of P. NED plateau flow patterns at mid-inspiration (V̇) were produced within the current bench setting when P fell below P'. V̇ was proportional to P, and the slope (ΔV̇/ΔP) increased linearly with P. P and P were the two final independent determinants of inspiratory flow. Our bench model closely mimics a flow-limited human UA, and the findings have implications for OSA treatment and research, especially for bench-testing auto-titrating devices in a more physiological way. NEW & NOTEWORTHY A respiratory model consisting of a collapsible tube was used to mimic a flow-limited human upper airway. Flow-limited breathing patterns including negative effort dependence were produced. Transmural and downstream pressures acting on the tube are the two independent determinants of the resulting inspiratory flow during flow limitation. The findings have implications for obstructive sleep apnea treatment and research, especially for bench-testing auto-titrating devices in a more physiological way.
人类的上呼吸道（UA）通常被建模为 Starling 电阻器。然而，一些阻塞性睡眠呼吸暂停（OSA）患者观察到的负努力依赖性（NED）与基于 Starling 电阻器模型的预测相矛盾，在该模型中，当流量受到限制时，吸气流量与吸气驱动压力无关。在由可塌陷管和主动肺模型（ASL5000）组成的呼吸台架模型中，通过在主动肺中从-1 到-20cmHO 改变吸气努力（肌肉压力），研究了吸气流量特性与上游、下游和腔外压力（分别表示为 P、P 和 P）之间的关系。P 由恒定气道压力装置提供，范围从 4 到 20cmHO，P 设置为 10 和 15cmHO。在流量限制开始时的上游阻力和对应 UA 开放的临界跨壁压力（P）被发现与 P、P 和 P 无关。当 P 低于特定值（P'）时，用固定 P，吸气峰流变得恒定且与 P 无关。当 P 低于 P'时，在当前台架设置中会产生吸气中期的 NED 平台流量模式。V̇与 P 成正比，斜率（ΔV̇/ΔP）随 P 线性增加。P 和 P 是吸气流量的两个最终独立决定因素。我们的台架模型紧密模拟了受限的人类 UA，研究结果对 OSA 治疗和研究具有重要意义，特别是对以更生理的方式对自动滴定设备进行台架测试。
使用由可塌陷管组成的呼吸模型来模拟受限的人类上呼吸道。产生了包括负努力依赖性在内的受限呼吸模式。作用于管的跨壁和下游压力是流量限制期间产生的最终吸气流量的两个独立决定因素。研究结果对阻塞性睡眠呼吸暂停的治疗和研究具有重要意义，特别是对以更生理的方式对自动滴定设备进行台架测试。
