Tidal breathing model describing end-tidal, alveolar, arterial and mixed venous CO2 and O2

2011 ◽  
Vol 101 (2) ◽  
pp. 166-172 ◽  
Author(s):  
Peter Poulsen ◽  
Dan S. Karbing ◽  
Stephen E. Rees ◽  
Steen Andreassen
Keyword(s):  
Tidal Breathing ◽  
Breathing Model ◽  
End Tidal ◽  
Mixed Venous

Tidal breathing model describing end-tidal, alveolar, arterial and mixed venous CO2 and O2

2009 ◽  
Vol 42 (12) ◽  
pp. 139-144
Author(s):  
Peter Poulsen ◽  
Dan S. Karbing ◽  
Stephen E. Rees ◽  
Steen Andreassen
Keyword(s):  
Tidal Breathing ◽  
Breathing Model ◽  
End Tidal ◽  
Mixed Venous

Lung volume, closing volume, and gas exchange

1982 ◽  
Vol 52 (6) ◽  
pp. 1453-1457 ◽  
Author(s):  
S. C. Morrison ◽  
D. G. Stubbing ◽  
P. V. Zimmerman ◽  
E. J. Campbell
Keyword(s):  
Gas Exchange ◽  
Lung Volume ◽  
Normal Subjects ◽  
Close Correlation ◽  
Closing Volume ◽  
Tidal Breathing ◽  
Co2 Partial Pressure ◽  
Residual Capacity ◽  
End Tidal ◽  
Arterial O2 Saturation

The effect of a voluntary reduction in lung volume on arterial O2 saturation (SaO2) was studied in 10 normal subjects aged 19–63 yr. SaO2 was measured by ear oximetry first during tidal breathing at functional residual capacity, and then during tidal breathing at 380 ml above residual volume. Tidal volume and breathing frequency were kept constant, and end-tidal CO2 partial pressure remained stable or fell in 9 out of 10 subjects. When lung volume was reduced, SaO2 fell by a mean of 1.5% (range 0–3%). Closing volume (CV) was measured by the N2-washout method (mean 0.89 liter, range 0.41–1.44). There was a close correlation between CV and the fall in SaO2 (r = 0.867, P = 0.001). Arterial and mixed venous CO2 were measured in one subject; the results indicated some fall in cardiac output following the lung volume change, but this accounted for less than half of the fall in SaO2. The relationship between CV and the lung volume at which tidal breathing occurs is an important determinant of pulmonary gas exchange through its effect on the matching of ventilation to perfusion.

Intramucosal PHi and arterial, mixed-venous, end-tidal and gastric PCO2 relationship in critically ill patients

2000 ◽  
Vol 17 (Supplement 19) ◽  
pp. 66
Author(s):  
I. Rovira ◽  
L. Sabater ◽  
G. Martínez ◽  
J. Balust ◽  
E. Zavala
Keyword(s):  
Critically Ill ◽  
Critically Ill Patients ◽  
End Tidal ◽  
Mixed Venous

Ventilatory effects of hypoxia and their dependence on PCO2

1975 ◽  
Vol 38 (1) ◽  
pp. 16-19 ◽  
Author(s):  
A. S. Rebuck ◽  
W. E. Woodley
Keyword(s):  
Oxygen Saturation ◽  
Healthy Subjects ◽  
Pulmonary Ventilation ◽  
Response Curves ◽  
Venous Pco2 ◽  
Progressive Hypoxia ◽  
Ventilatory Effects ◽  
Independent Variable ◽  
End Tidal ◽  
Mixed Venous

In 11 healthy subjects the effect of progressive hypoxia on pulmonary ventilation at various alveolar carbon dioxide pressures was studied. A rebreathing technique was used to produce hypoxia, CO2 was held constant and oxygen saturation was taken as the independent variable. We found a linear relationship between ventilation and falls in oxygen saturation when Pco2 was held at the resting mixed venous, end-tidal, or any intermediate level. Within this range of Pco2, a family of ventilation-So2 response curves was obtained for each subject. The effect of altering the isocapnic level was to change the slope and position of the ventilation-So2 response curve, the amount by which the slope changed being related to the slope for that subject at their mixed venous Pco2.

scholarly journals Comparison of methods of chemical loop gain measurement during tidal ventilation in awake healthy subjects

2018 ◽  
Vol 125 (6) ◽  
pp. 1681-1692 ◽  
Author(s):  
Plamen Bokov ◽  
Boris Matrot ◽  
Jorge Gallego ◽  
Christophe Delclaux
Keyword(s):  
Healthy Subjects ◽  
Minute Ventilation ◽  
Loop Gain ◽  
Tidal Breathing ◽  
Medium Frequency ◽  
Model Based ◽  
Gain Measurement ◽  
Explained Variance ◽  
End Tidal ◽  
Constrained Models

The loop gain (LG) is defined as the ratio of a ventilatory response over the perturbation in ventilation, and it is used to analyze ventilatory control stability. The LG can be derived from minute ventilation (V̇e), end-tidal Pco2 ([Formula: see text]), and end-tidal Po2 ([Formula: see text]) values. Several methods of LG assessment have been developed, which have never been compared. We evaluated the computability, the short-term repeatability, and the agreement of six published (or slightly modified) models for LG determination. These models included three unconstrained autoregressive models, univariate (V̇e), bivariate (V̇e, [Formula: see text]), and trivariate (V̇e, [Formula: see text], and [Formula: see text]), and three analytical transfer function constrained models based on V̇e, V̇e and CO2-sensitivity, and V̇e and central and peripheral CO2 sensitivities, respectively. The models were tested with tidal breathing data in 37 awake healthy subjects (median age 35 yr; 23 women, 14 men). Modeling failed in 11, 0, and 0 subjects for the three unconstrained models, respectively, and 4, 1, and 9 subjects for the three constrained models, respectively. Bland and Altman analyses of the LG values in the medium frequency range of two separate recordings demonstrated good repeatability for four models, excluding univariate and trivariate unconstrained models. The four repeatable models gave LG values that were in agreement (medium frequency LG, median 0.100–0.210), although the constrained model based on V̇e systematically overestimated LG values. The variances explained by these models were ∼20%. In conclusion, model-based analyses of tidal breathing were performed with different approaches that gave comparable results for chemical LG and explained variance. NEW & NOTEWORTHY Several methods of chemical loop gain measurement have been published but never compared. We show that a better repeatability is obtained with analytical constrained models compared with autoregressive unconstrained models and that the repeatable models gave comparable results of loop gain, even if the calculation based on ventilation-only recording gave higher values than those obtained with both ventilation and end-tidal Pco2 recording. The explained variance of ventilation was similar whatever the model.

A tidal breathing model of the inert gas sinewave technique for inhomogeneous lungs

2000 ◽  
Vol 124 (1) ◽  
pp. 65-83 ◽  
Author(s):  
J.P. Whiteley ◽  
D.J. Gavaghan ◽  
C.E.W. Hahn
Keyword(s):  
Inert Gas ◽  
Tidal Breathing ◽  
Breathing Model

Multiple-breath washout and washin experiments in steers

1996 ◽  
Vol 81 (2) ◽  
pp. 957-963 ◽  
Author(s):  
F. Rollin ◽  
D. Desmecht ◽  
S. Verbanck ◽  
A. Van Muylem ◽  
P. Lekeux ◽  
...  
Keyword(s):  
Phase Iii ◽  
Slope Ratio ◽  
Ventilation Distribution ◽  
Tidal Breathing ◽  
Ventilation Inhomogeneity ◽  
Multiple Breath Washout ◽  
The Mean ◽  
End Tidal ◽  
Sequential Emptying ◽  
Phase Iii Slope

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.

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