Effects of pulmonary vascular pressures and flow on airway and parenchymal mechanics in isolated rat lungs

F. Petak, W. Habre, Z. Hantos, Peter Sly, D.R. Morel

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59 Citations (Scopus)

Abstract

Changes in pulmonary hemodynamics have been shown to alter the mechanical properties of the lungs, but the exact mechanisms are not clear. We therefore investigated the effects of alterations in pulmonary vascular pressure and flow ((Q)over dot(p)) on the mechanical properties of the airways and the parenchyma by varying these parameters independently in three groups of isolated perfused normal rat lungs. The pulmonary capillary pressure (Pc-est), estimated from the pulmonary arterial (Ppa) and left atrial pressure (Pla), was increased at constant (Q)over dot(p) (n=7), or (Q)over dot(p) was changed at Pc-est=10 mmHg (n=7) and at Pc(es)t=20 mmHg (n=6). In each condition, the airway resistance (Raw) and parenchymal damping (G) and elastance (H) were identified from the low-frequency pulmonary input impedance spectra. The results of measurements made under isogravimetric conditions were analyzed. The changes observed in the mechanical parameters were consistent with an altered Pla: monotonous increases in Raw were observed with increasing Pla, whereas G and H were minimal at Pla of similar to7-10 mmHg and increased at lower and higher Pla. The results indicate that Pla, and not Ppa or (Q)over dot(p) is the primary determinant of the mechanical condition of the lungs after acute changes in pulmonary hemodynamics: the parenchymal mechanics are impaired if Pla is lower or higher than physiological, whereas airway narrowing occurs at high Pla.
Original languageEnglish
Pages (from-to)169-178
JournalJournal of Applied Physiology
Volume92
Publication statusPublished - 2002

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