Puddy A, Giesbrecht G, Sanii R, Younes M
Department of Medicine, University of Manitoba, Winnipeg, Canada.
J Appl Physiol (1985). 1992 Jun;72(6):2267-70. doi: 10.1152/jappl.1992.72.6.2267.
Conscious humans easily detect loads applied to the respiratory system. Resistive loads as small as 0.5 cmH2O.l-1.s can be detected. Previous work suggested that afferent information from the chest wall served as the primary source of information for load detection, but the evidence for this was not convincing, and we recently reported that the chest wall was a relatively poor detector for applied elastic loads. Using the same setup of a loading device and body cast, we sought resistive load detection thresholds under three conditions: 1) loading of the total respiratory system, 2) loading such that the chest wall was protected from the load but airway and intrathoracic pressures experienced negative pressure in proportion to inspiratory flow, and 3) loading of the chest wall alone with no alteration of airway or intrathoracic pressure. The threshold for detection for the three types of load application in seven normal subjects was 1.17 +/- 0.33, 1.68 +/- 0.45, and 6.3 +/- 1.38 (SE) cmH2O.l-1.s for total respiratory system, chest wall protected, and chest wall alone, respectively. We conclude that the active chest wall is a less potent source of information for detection of applied resistive loads than structures affected by negative airway and intrathoracic pressure, a finding similar to that previously reported for elastic load detection.
清醒的人很容易察觉到施加于呼吸系统的负荷。低至0.5 cmH₂O·l⁻¹·s的阻力负荷都能被检测到。先前的研究表明，来自胸壁的传入信息是负荷检测的主要信息来源，但这方面的证据并不令人信服，而且我们最近报告称，胸壁对于施加的弹性负荷而言是一个相对较差的检测器。使用相同的加载装置和身体模型设置，我们在三种条件下探寻阻力负荷检测阈值：1）整个呼吸系统加载；2）加载时保护胸壁不受负荷影响，但气道和胸腔内压力与吸气流量成比例地承受负压；3）仅对胸壁加载，而不改变气道或胸腔内压力。七名正常受试者在这三种负荷施加类型下的检测阈值分别为：整个呼吸系统加载时为1.17±0.33 cmH₂O·l⁻¹·s，胸壁受保护时为1.68±0.45 cmH₂O·l⁻¹·s，仅胸壁加载时为6.3±1.38（标准误）cmH₂O·l⁻¹·s。我们得出结论，与受气道和胸腔内负压影响的结构相比，活跃的胸壁对于检测施加的阻力负荷而言是一个效力较弱的信息来源，这一发现与先前关于弹性负荷检测的报告类似。
