 Multiple-Breath Washout and Washin Experiments in SteersRollin, Frédéric  ; Desmecht, Daniel ; et alin Journal of Applied Physiology (Bethesda, Md. : 1985) (1996), 81(2), 957-63 Multiple-breath N2 washouts (WO) and washins (WI) were performed during regular tidal breathing in 11 unsedated healthy steers approaching pulmonary functional maturity (mean body weight = 271 kg). They ... [more ▼] Multiple-breath N2 washouts (WO) and washins (WI) were performed during regular tidal breathing in 11 unsedated healthy steers approaching pulmonary functional maturity (mean body weight = 271 kg). They inspired 20% O2 in 80% Ar during the WO and air during the WI. For each steer, we computed two indexes of ventilation inhomogeneity from the N2 WO curves: 1) the curvilinearity of the logarithm of end-tidal N2 concentrations as a function of cumulative expired volume reflected in the ratio of two slopes fitted between 100 and 50% and between 50 and 10%, respectively, of end-tidal N2 concentration of the first breath of the WO; and 2) the N2 phase III slope divided by the mean expired concentration (Sn) of each breath also plotted as a function of cumulative expired volume. Equivalent computation of both parameters was done on WI and WO curves, and similar results were obtained. The mean slope ratio was 0.812 +/- 0.119 (SD) for all the steers, which is consistent with topographic gravity-dependent specific ventilation distribution inhomogeneity. Sn was independent of the breath number both for WO and WI (mean Sn = 0.130 +/- 0.057 liters-1), suggesting that emptying between unequally ventilated units, is synchronous. This behavior resembles that observed in rats postmortem (S. Verbanck, E.R. Weibel, and M. Paiva. J. Appl Physiol. 71: 847-854, 1991) but contrasts with experiments in humans, in whom convection-dependent ventilation inhomogeneities generate a marked increase in Sn throughout the entire WO (A. B. H. Crawford, M. Makowska, M. Paiva, and L. A. Engel. J. Appl. Physiol. 59: 838-846, 1985). This is surprising because one would expect gravity-dependent sequential emptying in animals of this size. [less ▲] Detailed reference viewed: 19 (1 ULg)Measurement of pulmonary inertance in EquidsArt, Tatiana ; Lekeux, Pierre ; Gustin, Pascal et alin European Respiratory Journal (1989), 2 Detailed reference viewed: 1 (0 ULg)Inertial pressures in exercising poniesArt, Tatiana ; Lekeux, Pierre ; Gustin, Pascal et alin Archives Internationales de Physiologie et de Biochimie (1989) Detailed reference viewed: 1 (0 ULg) Inertance of the Respiratory System in PoniesArt, Tatiana ; Lekeux, Pierre ; Gustin, Pascal et alin Journal of Applied Physiology (Bethesda, Md. : 1985) (1989), 67(2), 534-540 The purpose of the present work was to measure the pulmonary inertance (IL) in ponies and to analyze its potential influence on the mechanics of breathing and on their aptitude to increase ventilation ... [more ▼] The purpose of the present work was to measure the pulmonary inertance (IL) in ponies and to analyze its potential influence on the mechanics of breathing and on their aptitude to increase ventilation during exercise. Five healthy ponies 2.4-4 yr old [mean wt 255 +/- 15 (SE) kg] were used. On the one hand, inertance of the respiratory system (Irs) was computed from the value of the resonant frequency (fr) measured by the forced oscillation technique. On the other hand, respiratory airflow, tidal volume (VT), and transpulmonary pressure (PL) changes were recorded while the ponies were performing a light treadmill exercise, and IL was calculated as the ratio of the associated differences in inertial pressure (delta Pin) to volume acceleration (delta V). Respiratory airflow and VT were measured with a Fleisch pneumotachograph (no. 5) and PL with an intraesophageal balloon catheter. First, the protocol was carried out with the ponies breathing air and He-O2, second, while the ponies breathed through two additional tubes (100 cm long, 3 cm ID), then one, and finally none, fixed on the Fleisch pneumotachograph. Finally, the contribution of the extra- vs. the intrathoracic airways to IL was estimated by measuring the lateral midtracheal pressure recorded simultaneously with the aforementioned parameters. The values of Irs calculated with fr and of IL calculated on the basis of the delta Pin-delta V ratio were 29.8 +/- 0.4 and 19.8 +/- 1.0.10(-4) kPa.l-1.s-2, respectively. During He-O2 breathing IL decreased about three times; this result was similar to the predicted decrease based on gas density only.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲] Detailed reference viewed: 26 (5 ULg)Could pulmonary inertance be a limiting factor of ventilation during exercise in the equine species ?Art, Tatiana ; Lekeux, Pierre ; Gustin, Pascal et alin Proceedings of the 7th Comparative Respiratory Society Meeting (1988) Detailed reference viewed: 5 (0 ULg) |
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