Gunst S J, Warner D O, Wilson T A, Hyatt R E
Department of Physiology and Biophysics, Mayo Clinic, Rochester 55905.
J Appl Physiol (1985). 1988 Dec;65(6):2490-7. doi: 10.1152/jappl.1988.65.6.2490.
The objective of this investigation was to determine the minimum transpulmonary pressure (PL) at which the forces of interdependence between the airways and the lung parenchyma can prevent airway closure in response to maximal stimulation of the airways in excised canine lobes. We first present an analysis of the relationship between PL and the transmural pressure (Ptm) that airway smooth muscle must generate to close the airways. This analysis predicts that airway closure can occur at PL less than or equal to 10 cmH2O with maximal airway stimulation. We tested this prediction in eight excised canine lobes by nebulizing 50% methacholine into the airways while the lobe was held at constant PL values ranging from 25 to 5 cmH2O. Airway closure was assessed by comparing changes in alveolar pressure (measured by an alveolar capsule technique) and pressure at the airway opening during low-amplitude oscillations in lobar volume. Airway closure occurred in two of the eight lobes at PL = 10 cmH2O; in an additional five it occurred at PL = 7.5 cmH2O. We conclude that the forces of parenchymal interdependence per se are not sufficient to prevent airway closure at PL less than or equal to 7.5 cmH2O in excised canine lobes.
本研究的目的是确定在离体犬肺叶中，气道与肺实质之间的相互依存力能够防止气道在最大气道刺激下关闭时的最小跨肺压（PL）。我们首先分析了PL与气道平滑肌关闭气道必须产生的跨壁压（Ptm）之间的关系。该分析预测，在最大气道刺激下，当PL小于或等于10 cmH₂O时可能发生气道关闭。我们在八个离体犬肺叶中验证了这一预测，在将肺叶维持在25至5 cmH₂O的恒定PL值时，向气道内雾化50%的乙酰甲胆碱。通过比较在肺叶容积低振幅振荡期间肺泡压力（通过肺泡囊技术测量）和气道开口处压力的变化来评估气道关闭情况。在八个肺叶中有两个在PL = 10 cmH₂O时发生气道关闭；另有五个在PL = 7.5 cmH₂O时发生气道关闭。我们得出结论，在离体犬肺叶中，实质相互依存力本身不足以防止在PL小于或等于7.5 cmH₂O时气道关闭。
