Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.
Respiratory Department, Chengdu First People's Hospital, Chengdu, People's Republic of China.
Am J Physiol Lung Cell Mol Physiol. 2022 Jun 1;322(6):L882-L889. doi: 10.1152/ajplung.00033.2022. Epub 2022 May 10.
Lung resistance () is determined by airway and parenchymal tissue resistance, as well as the degree of heterogeneity in airway constriction. Deep inspirations (DIs) are known to reverse experimentally induced increase in , but the mechanism is not entirely clear. The first step toward understanding the effect of DI is to determine how each of the resistance components is affected by DI. In the present study, we measured and apparent airway resistance (, which combines the effects of airway resistance and airway heterogeneity) simultaneously before and after a DI in acetylcholine (ACh)-challenged ex vivo sheep lungs. We found that at normal breathing frequency (0.25 Hz) ACh-challenge led to a doubling of , 80.3% of that increase was caused by an increase in ; the increase in apparent tissue resistance () was insignificant. 57.7% of the increase in was abolished by a single DI. After subtracting from , the remaining was mostly independent of ACh-challenge and its reduction after a DI came mostly from the change in the mechanical properties of lung parenchyma. We conclude that at normal breathing frequency, in an unchallenged lung is mostly composed of , and the increase in due to ACh-challenge stems mostly from the increase in and that both and can be greatly reduced by a DI, likely due to a reduction in true airway resistance and heterogeneity, as well as parenchymal tissue hysteresis post DI.
肺阻力（）由气道和肺实质组织阻力以及气道收缩异质性的程度决定。深吸气（DIs）已知可逆转实验诱导的增加，但机制尚不完全清楚。了解 DI 影响的第一步是确定 DI 如何影响每个阻力成分。在本研究中，我们在乙酰胆碱（ACh）挑战的离体绵羊肺中，在 DI 前后同时测量了气道阻力（）和表观气道阻力（，它结合了气道阻力和气道异质性的影响）。我们发现，在正常呼吸频率（0.25 Hz）下，ACh 挑战导致增加了一倍，其中 80.3%的增加是由于增加引起的；气道组织阻力（）的增加不显著。单次 DI 可消除增加的 57.7%。从中减去后，剩余的主要与 ACh 挑战无关，并且 DI 后其减少主要来自于肺实质的机械特性的变化。我们得出结论，在正常呼吸频率下，未受挑战的肺中的主要由组成，而 ACh 挑战引起的增加主要来自于的增加，并且和都可以通过 DI 大大降低，可能是由于 DI 后真正的气道阻力和异质性以及组织滞后的降低。
