Flinders Health and Medical Research Institute: Sleep Health (formerly Adelaide Institute for Sleep Health), College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, Australia.
The Medical Device Research Institute, College of Science and Engineering, Flinders University, Bedford Park, South Australia, Australia.
J Appl Physiol (1985). 2024 Jun 1;136(6):1418-1428. doi: 10.1152/japplphysiol.00028.2024. Epub 2024 Apr 11.
Breathing effort is important to quantify to understand mechanisms underlying central and obstructive sleep apnea, respiratory-related arousals, and the timing and effectiveness of invasive or noninvasive mechanically assisted ventilation. Current quantitative methods to evaluate breathing effort rely on inspiratory esophageal or epiglottic pressure swings or changes in diaphragm electromyographic (EMG) activity, where units are problematic to interpret and compare between individuals and to measured ventilation. This paper derives a novel method to quantify breathing effort in units directly comparable with measured ventilation by applying respiratory mechanics first principles to convert continuous transpulmonary pressure measurements into "attempted" airflow expected to have arisen without upper airway obstruction. The method was evaluated using data from 11 subjects undergoing overnight polysomnography, including six patients with obesity with severe obstructive sleep apnea (OSA), including one who also had frequent central events, and five healthy-weight controls. Classic respiratory mechanics showed excellent fits of airflow and volume to transpulmonary pressures during wake periods of stable unobstructed breathing (means ± SD, = 0.94 ± 0.03), with significantly higher respiratory system resistance in patients compared with healthy controls (11.2 ± 3.3 vs. 7.1 ± 1.9 cmHO·L·s, = 0.032). Subsequent estimates of attempted airflow from transpulmonary pressure changes clearly highlighted periods of acute and prolonged upper airway obstruction, including within the first few breaths following sleep onset in patients with OSA. This novel technique provides unique quantitative insights into the complex and dynamically changing interrelationships between breathing effort and achieved airflow during periods of obstructed breathing in sleep. Ineffective breathing efforts with snoring and obstructive sleep apnea (OSA) are challenging to quantify. Measurements of esophageal or epiglottic pressure swings and diaphragm electromyography are useful, but units are problematic to interpret and compare between individuals and to measured ventilation. This paper derives a novel method that uses esophageal pressure and respiratory mechanics first principles to quantify breathing effort as "attempted" flow and volume in units directly comparable with measured airflow, volume, and ventilation.
呼吸努力对于理解中枢性和阻塞性睡眠呼吸暂停、呼吸相关觉醒以及侵入性或非侵入性机械辅助通气的时机和效果的机制非常重要。目前评估呼吸努力的定量方法依赖于吸气食管或会厌压力波动或膈肌肌电图（EMG）活动的变化，其中单位对于个体之间的解释和比较以及与测量通气的比较存在问题。本文通过将呼吸力学第一原理应用于连续跨肺压力测量，将其转换为“预期”的气流，而无需上气道阻塞，从而推导出一种新的方法来量化单位的呼吸努力，该方法与测量通气直接可比。该方法使用 11 名接受过夜多导睡眠图检查的受试者的数据进行了评估，包括 6 名患有严重阻塞性睡眠呼吸暂停（OSA）的肥胖患者，其中 1 名患者还经常出现中枢事件，以及 5 名健康体重对照者。在稳定无阻塞呼吸的清醒期间，经典呼吸力学对气流和体积与跨肺压力的拟合非常好（平均值±标准差，=0.94±0.03），与健康对照组相比，患者的呼吸系统阻力明显更高（11.2±3.3 与 7.1±1.9 cmHO·L·s，=0.032）。从跨肺压力变化中随后估计的预期气流清楚地突出了急性和长时间上气道阻塞的时期，包括 OSA 患者睡眠开始后的最初几次呼吸中。这种新的技术提供了独特的定量见解，了解阻塞性睡眠呼吸暂停期间呼吸努力和实现气流之间复杂且动态变化的相互关系。打鼾和阻塞性睡眠呼吸暂停（OSA）的无效呼吸努力难以量化。食管或会厌压力波动和膈肌肌电图的测量很有用，但单位对于个体之间的解释和比较以及与测量通气的比较存在问题。本文推导了一种新的方法，该方法使用食管压力和呼吸力学第一原理来量化呼吸努力，将其作为与测量气流、体积和通气直接可比的单位的“预期”流量和体积。
