Mechanism of increased collateral airway resistance during inhomogenous inflation of excised dog lungs

Fuller, S. D.; Robinson, N. E.

doi:10.1016/0034-5687(88)90034-5

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…Most authors conclude that both airway compartments display similar dependencies on PL or lung volume (12,19) and respond similarly to constrictor stimuli (1,12,13,17), whereas others find the segmental airway resistance to be negligible in comparison with Rcoll (14), or even independent of lung volume (11). In the present study, stable values of R 1 were estimated from the frequency-domain measurements at all PL levels in most regions, and the mean value of the R 1 -to-R 2 ratios (R 1 /R 2 ) at PL of 5 cmH 2 O (0.115) falls into the wide variety and range of data reported previously: from 0.01 to 0.1 (23), 0.15 (11), and from 0.11 to 0.2 (6). However, it is equally notable that the range of our individual R 1 /R 2 values extends from 0.012 to 0.497.…”

Section: Discussionmentioning

confidence: 99%

Mechanical impedance of the lung periphery

Hantos

Peták²,

Adamicza

et al. 1997

Journal of Applied Physiology

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The mechanics of the regional airways and tissues was studied in isolated dog lobes by means of a modified wave-tube technique. Small-amplitude pseudorandom forced oscillations between 0.1 and 48 Hz were applied through catheters wedged in 2-mm-diameter bronchi in three regions of each lobe at translobar pressures (PL) of 10, 7, 5, 3, 2, and 1 cmH2O. The measured regional input impedances were fitted by a model containing the resistance (R1) and inertance (I) of the regular (segmental) airways, the resistance of the collateral channels (R2), and the damping (G) and elastance (H) of the local tissues. This model gave far better fits to the data on impedance of the lung periphery than when G and H were replaced by a single tissue compliance, which explains why interruption of segmental flow did not lead to monoexponential pressure decay in previous studies. The interlobar and intralobar variances of the parameters were equally significant, and poor correlations were found between the airway parameters R1 and R2 and between any airway and tissue parameter (e.g., R1 and H). R2 was on average approximately 10 times higher than R1, although the R2-to-R1 ratios and their dependencies on PL were regionally highly variable. However, for the total of 33 regions studied, the PL dependence was the same for R1 and R2, which may reflect similar morphological structures for the regular and collateral airways. The dependencies of G and H on PL showed high interregional variations; generally, however, they assumed their minima at medium PL values (approximately 5 cmH2O).

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Section: Discussionmentioning

confidence: 99%

Mechanical impedance of the lung periphery

Hantos

Peták²,

Adamicza

et al. 1997

Journal of Applied Physiology

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“…Studies in isolated lungs [6,25], intact dogs [4,15], and humans [3,10] have shown that Rcoll is highly influenced by lung volume of both the wedged segment and the overlying lung. Rcoll decreases as lung volumes are increased above the functional residual capacity and increases very rapidly at lower lung volumes.…”

Section: Introductionmentioning

confidence: 99%

Influence of lung volume hysteresis on collateral resistance in intact dogs

Cormier

Atton

Sériès

1993

Lung

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Collateral resistance (Rcoll) is highly lung volume dependent. We studied 12 dogs in an attempt to evaluate the influence of hysteresis on this volume dependency. Rcoll measurements were obtained at baseline and at different lung volumes as modified by the application of negative or positive extrathoracic pressure (ETP) in an iron lung. ETP was modified in 5 cmH2O steps from +20 to -25 cmH2O) and back to +20 cmH2O on the first day (cycle 1), and, in 4 of these dogs, from -25 to +20 cmH2O and back to -25 cmH2O on a second day (cycle 2). The behavior of Rcoll for both cycles was the same in all dogs, varying inversely with the changes in end-expiratory lung volume (EELV). All dogs presented a similar pattern: during cycle 1, for a same lung volume, Rcoll was much higher during the deflation limb than during the inflation limb. For cycle 2, Rcoll at a given lung volume was similar whether measured during the inflation or deflation limb. Changes in EELV were higher for any given negative ETP during the deflation than during the inflation limb of the pressure cycles (e.g., for the 4 dogs who had both cycles, at -15 cmH2O ETP of cycle 2 the increase in EELV was 1167 +/- 121 ml during deflation and 525 +/- 102 ml during the subsequent inflation [mean +/- SEM]). In conclusion, the effects of hysteresis on Rcoll and on lung volumes are similar, except at low lung volumes during the deflation limb of cycle 2.(ABSTRACT TRUNCATED AT 250 WORDS)

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