Abstract
A model study is made of the contribution that continuing respiratory gas exchange makes to the alveolar plateau slope for O2 during air breathing. Calculations in the model of the O2 concentration appearing at the mouth during expiration, are performed for single breaths of air at constant flow rates 18 litres/min and 120 litres/min. At 18 litres/min the breathing period is 5 sec, the initial lung volume is 2300 ml, and the O2 uptake rate is 300 ml STPD/min; whereas at 120 litres/min these parameters are 4 sec, 1200 ml, and 1800 ml STPD/min respectively. In each case the initial lung O2 tension is taken to be 98 mm Hg. It is found that at 18 litres/min, the O2 concentration difference on the alveolar plateau over the last second of expiration is 0.4 mm Hg when gas exchange is omitted and 1.2 mm Hg when gas exchange is included in the model. At 120 litres/min, this difference is zero and 5.0 mm Hg respectively. The gas exchange component predicted from a corresponding well-mixed compartment model is the same at 18 litres/min (0.8 mm Hg) but is 6.0 mm Hg at 120 litres/min.
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Literature
Bunhuys, A. 1964. “Distribution of Inspired Gas in the Lungs.” InHandbook of Physiology, Section 3: Respiration, Vol. 1.Am. Physiol. Soc., Washington, D.C. pp. 715–733.
Chang, H. and L. E. Farhi. 1973. “On Mathematical Analysis of Gas Transport in the Lung.”Resp. Physiol.,18, 370–385.
—, R. C. Tai and L. E. Farhi. 1975. “Some Implications of Ternary Diffusion in the Lung.”Ibid.,23, 109–120.
Davidson, M. R. 1975. “Lung Gas Mixing During Expiration Following an Inspiration of Air.”Bull. Math. Biol.,37, 113–126.
— and J. M. Fitz-Gerald. 1974. “Transport of O2 Along a Model Pathway through the Respiratory Region of the Lung.”Bull. Math. Biol.,36, 275–303.
— and —. 1974. “Flow Patterns in Models of Small Airway Units of the Lung.”J. Fluid Mech.,52, 161–177.
DuBois, A. B., R. C. Fowler, A. Soffer and W. O. Fenn. 1952. “Alveolar CO2 Measured by Expiration Into the Rapid Infrared Gas Analyzer.”J. Appl. Physsiol. 4, 526–534.
Farhi, L. E. 1969. “Diffusive and Convective Movement of Gas in the Lung.” In Circulatory and Respiratory Mass Transport—A Ciba Foundation Symposium. Wolstenholme, G. E. W. and J. Knight, Eds., Churchill, London. pp 277–293.
Fowler, W. S. 1952. “Intrapulmonary Distribution of Inspired Gas.”Physiol. Rev.,32, 1–20.
Lin, K. H. and G. Cumming. 1973. “A Model of Time-Varying Gas Exchange in the Human Lung During A Respiratory Cycle at Rest.”Resp. Physiol.,17, 93–112.
Meade, F., N. Pearl, and M. J. Saunders. 1967. Distribution of Lung Function\((\dot V_A /\dot Q)\) in Normal Subjects Deduced from Changes in Alveolar Gas Tensions During Expiration.”Scand. J. Resp. Dis.,48, 354–365.
Pedley, T. J. 1970. A Theory for Gas Mixing in a Simple Model of the Lung.” In Fluid Dynamics of Blood Circulation and Respiratory Flow, AGARD Conference Proceedings No. 65.
Piiper, J. and P. Scheid. 1971. “Respiration: Alveolar Gas Exchange.” InAnnual Review of Physiology, Vol.33, pp. 131–154.
Sikand, R., P. Cerretelli and L. E. Farhi. 1966. “Effect of\(\dot V_A \) and\(\dot V_A /\dot Q\) Distribution and of Time on the Alveolar Plateau.”J. Appl. Physiol.,21, 1331–1337.
Weibel, E. R. 1963.Morphometry of the Human Lung. Berlin: Springer.
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Davidson, M.R. The influence of gas exchange on lung gas concentrations during air breathing. Bltn Mathcal Biology 39, 73–86 (1977). https://doi.org/10.1007/BF02460682
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DOI: https://doi.org/10.1007/BF02460682