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Limitations to the Efficiency of Pulmonary Gas Exchange During Exercise in Man

  • M. D. Hammond
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 227)

Abstract

The human lung must function over a wide range of metabolic demands and environmental conditions. It is not rare for oxygen consumption (\(\rm\dot{v}\)O2) to vary from 3-5 ml · kg · min−1 at rest to as much as 70 ml · kg · min−1 during exercise only moments later, or for inspired PO2 (PIO2) to range from 150 Torr (sea level) to 80 Torr (equivalent altitude 4500 meters) or less over a period of hours, to days. The ability to function in these different circumstances comes with a small price: although the lung is remarkably efficient at rest at sea level, it becomes less so at higher \(\rm\dot{v}\)O2 (Asmussen and Nielsen, 1960), particularly at high altitude. For example, in healthy resting subjects the ideal alveolar-arterial PO2 difference (A-aDO2) is normally only 5-10 Torr, but it may increase to 25 Torr or more during neavy exercise (Dempsey et al., 1984). While this increased gradient has relatively little effect on arterial O2 content at sea level, it can lead to substantial additional arterial desaturation at altitude, where subjects are operating on the steep descending slope of the oxyhemoglobin dissociation curve.

Keywords

Diffusion Limitation Pulmonary Capillary Wedge Pressure Normobaric Hypoxia Simulated Altitude Oxyhemoglobin Dissociation Curve 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Asmussen, E. and M. Nielsen (1960). Alveolar-arterial gas exchange at rest and during work at different tensions. Acta. Physiol. Scand. 50:153–166.PubMedCrossRefGoogle Scholar
  2. Dempsey, J.A., P.G. Hanson and K.S. Henderson (1984). Exercise induced arterial hypoxemia in healthy human subjects at sea level. J. Physiol. Lond. 355:161–175.PubMedGoogle Scholar
  3. Derks, C.M. (1980). Ventilation-perfusion distribution in young and old volunteers during mild exercise. Bull. Eur. Physiopathol. Respir. 16:145–154.PubMedGoogle Scholar
  4. Gale, G.E., J. Torre-Bueno, R. Moon, H.A. Saltzman and P.D. Wagner (1985). \(\rm\dot{v}\)A/\({\dot Q}\) inequality in normal man during exercise at sea level and simulated altitude. J. Appl. Physiol. 58:978–988.PubMedGoogle Scholar
  5. Gledhill, N., A.B. Froese and J.A. Dempsey (1977). Ventilation to perfusion distribution during exercise in health. In: Muscular Exercise and the Lung, edited by J. Dempsey and C.E. Reed. Madison WI: Univ. of Wisconsin Press, p. 325–342.Google Scholar
  6. Hammond, M.D., A.E. Gale, K.S. Kapitan, A.R. Ries and P.D. Wagner (1986a) Pulmonary gas exchange in humans during exercise at sea level. J. Appl. Physiol. 60:1590–1598.PubMedGoogle Scholar
  7. Hammond, M.D., G.E. Gale, K.S. Kapitan, A.R. Ries and P.D. Wagner (1986b). Pulmonary gas exchange in humans during normobaric hypoxic exercise. J. Appl. Physiol. 61;1749–57.Google Scholar
  8. Miles, D.S., C.E. Doerr, S.A. Schonfeld, D.E. Sinks and R.W. Gotshall (1983). Changes in pulmonary diffusing capacity and closing volume after running a marathon. Respir. Physiol. 52:349–359.PubMedCrossRefGoogle Scholar
  9. Piiper, J. and P. Scheid (1980). Blood-gas equilibration in lungs. In: Pulmonary Gas Exchange. Vol. 1 Ventilation, Blood Flow and Diffusion, edited by J.B. West, New York, Academic Press, pp. 131–171.Google Scholar
  10. Torre-Bueno, J., P.D. Wagner, H.A. Saltzman, G.E. Gale and R.E. Moon (1985). Diffusion limitation in normal man during exercise at sea level and simulated altitude. J. Appl. Physiol. 58:989–995.PubMedGoogle Scholar
  11. Wagner, P.D., R.B. Laravuso, R.R. Uhl and J.B. West (1974a). Continuous distributions of ventilation-perfusion ratios in normal subjects breathing air and 100% O2. J- Clin. Invest. 54:54–68.PubMedCrossRefGoogle Scholar
  12. Wagner, P.D., H.A. Saltzman and J.B. West (1974b). Measurement of continuous distributions of ventilation-perfusion ratios: theory. J. Appl. Physiol. 36:588–599.PubMedGoogle Scholar
  13. Wagner, P.D. (1982). Influence of mixed venous PO2 on diffusion of across the blood:gas barrier. Clin. Physiol. 2:205–215.CrossRefGoogle Scholar
  14. Wagner, P.D., G.E. Gale, R.E. Moon, J.R. Torre-Bueno, B.W. Stolp and H.A. Saltzman (1986a). Pulmonary gas exchange in humans exercising at sea level and simulated altitude. J. Appl. Physiol. 61:260–270.PubMedGoogle Scholar
  15. Wagner, P.D., J.R. Sutton, J.T. Reeves, A. Cymerman, B.M. Groves and M.K. Malconian (1986b). \(\rm\dot{v}\)A/Q \({\dot Q}\) inequality at rest and during exercise throughout a simulated ascent of Mt. Everest. Fed. Pro. 45:4232.Google Scholar

Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • M. D. Hammond
    • 1
  1. 1.Division of Pulmonary and Critical Medicine Department of Internal MedicineUniversity of South Florida, College of Medicine James A. Haley Veterans HospitalTampaUSA

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