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Semin Respir Crit Care Med 2023; 44(05): 555-568
DOI: 10.1055/s-0043-1770060
Review Article

Gas Exchange in the Lung

Johan Petersson
1   Section of Anesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
2   Department of Anaesthesiology, Surgical Services and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
,
Robb W. Glenny
3   Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, Washington
4   Department of Physiology and Biophysics, University of Washington, Seattle, Washington
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Abstract

Gas exchange in the lung depends on tidal breathing, which brings new oxygen to and removes carbon dioxide from alveolar gas. This maintains alveolar partial pressures that promote passive diffusion to add oxygen and remove carbon dioxide from blood in alveolar capillaries. In a lung model without ventilation and perfusion (V̇AQ̇) mismatch, alveolar partial pressures of oxygen and carbon dioxide are primarily determined by inspiratory pressures and alveolar ventilation. Regions with shunt or low ratios worsen arterial oxygenation while alveolar dead space and high lung units lessen CO2 elimination efficiency. Although less common, diffusion limitation might cause hypoxemia in some situations. This review covers the principles of lung gas exchange and therefore mechanisms of hypoxemia or hypercapnia. In addition, we discuss different metrics that quantify the deviation from ideal gas exchange.

Keywords

ventilation-perfusion ratio - respiratory dead space - respiratory physiology - pulmonary ventilation - hypoxia - hypercapnia


Publication History

Article published online:
10 October 2023

© 2023. Thieme. All rights reserved.

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  • References

  • 1 Weibel ER, Federspiel WJ, Fryder-Doffey F. et al. Morphometric model for pulmonary diffusing capacity. I. Membrane diffusing capacity. Respir Physiol 1993; 93 (02) 125-149
    CrossrefPubMedGoogle Scholar
  • 2 Weibel ER. What makes a good lung?. Swiss Med Wkly 2009; 139 (27–28): 375-386
    PubMedGoogle Scholar
  • 3 Gehr P, Bachofen M, Weibel ER. The normal human lung: ultrastructure and morphometric estimation of diffusion capacity. Respir Physiol 1978; 32 (02) 121-140
    CrossrefPubMedGoogle Scholar
  • 4 Riley RL, Cournand A. Ideal alveolar air and the analysis of ventilation-perfusion relationships in the lungs. J Appl Physiol 1949; 1 (12) 825-847
    CrossrefPubMedGoogle Scholar
  • 5 Cruickshank S, Hirschauer N. The alveolar gas equation. Contin Educ Anaesth Crit Care Pain 2004; 4: 24-27
    CrossrefPubMedGoogle Scholar
  • 6 Wang MC, Corbridge TC, McCrimmon DR, Walter JM. Teaching an intuitive derivation of the clinical alveolar equations: mass balance as a fundamental physiological principle. Adv Physiol Educ 2020; 44 (02) 145-152
    CrossrefPubMedGoogle Scholar
  • 7 Roughton FJ, Forster RE. Relative importance of diffusion and chemical reaction rates in determining rate of exchange of gases in the human lung, with special reference to true diffusing capacity of pulmonary membrane and volume of blood in the lung capillaries. J Appl Physiol 1957; 11 (02) 290-302
    CrossrefPubMedGoogle Scholar
  • 8 Agustí AG, Roca J, Gea J, Wagner PD, Xaubet A, Rodriguez-Roisin R. Mechanisms of gas-exchange impairment in idiopathic pulmonary fibrosis. Am Rev Respir Dis 1991; 143 (02) 219-225
    CrossrefPubMedGoogle Scholar
  • 9 Hughes JM, Bates DV. Historical review: the carbon monoxide diffusing capacity (DLCO) and its membrane (DM) and red cell (Theta.Vc) components. Respir Physiol Neurobiol 2003; 138 (2–3): 115-142
    CrossrefPubMedGoogle Scholar
  • 10 Hughes JM, Pride NB. In defence of the carbon monoxide transfer coefficient Kco (TL/VA). Eur Respir J 2001; 17 (02) 168-174
    CrossrefPubMedGoogle Scholar
  • 11 Glenny RW. Determinants of regional ventilation and blood flow in the lung. Intensive Care Med 2009; 35 (11) 1833-1842
    CrossrefPubMedGoogle Scholar
  • 12 Glenny RW, Lamm WJ, Albert RK, Robertson HT. Gravity is a minor determinant of pulmonary blood flow distribution. J Appl Physiol 1991; 71 (02) 620-629
    CrossrefPubMedGoogle Scholar
  • 13 Glenny RW, Bernard S, Robertson HT, Hlastala MP. Gravity is an important but secondary determinant of regional pulmonary blood flow in upright primates. J Appl Physiol 1999; 86 (02) 623-632
    CrossrefPubMedGoogle Scholar
  • 14 West JB, Dollery CT, Naimark A. Distribution of blood flow in isolated lung; relation to vascular and alveolar pressures. J Appl Physiol 1964; 19: 713-724
    CrossrefPubMedGoogle Scholar
  • 15 Hlastala MP, Glenny RW. Vascular structure determines pulmonary blood flow distribution. News Physiol Sci 1999; 14: 182-186
    PubMedGoogle Scholar
  • 16 Glenny RW, Polissar L, Robertson HT. Relative contribution of gravity to pulmonary perfusion heterogeneity. J Appl Physiol 1991; 71 (06) 2449-2452
    CrossrefPubMedGoogle Scholar
  • 17 Glenny RW, Robertson HT. Fractal properties of pulmonary blood flow: characterization of spatial heterogeneity. J Appl Physiol 1990; 69 (02) 532-545
    CrossrefPubMedGoogle Scholar
  • 18 Petersson J, Rohdin M, Sánchez-Crespo A. et al. Regional lung blood flow and ventilation in upright humans studied with quantitative SPECT. Respir Physiol Neurobiol 2009; 166 (01) 54-60
    CrossrefPubMedGoogle Scholar
  • 19 Wagner PD, Laravuso RB, Uhl RR, West JB. Continuous distributions of ventilation-perfusion ratios in normal subjects breathing air and 100 per cent O2. J Clin Invest 1974; 54 (01) 54-68
    CrossrefPubMedGoogle Scholar
  • 20 West JB. Regional differences in gas exchange in the lung of erect man. J Appl Physiol 1962; 17: 893-898
    CrossrefPubMedGoogle Scholar
  • 21 Lumb AB. Nunn's Applied Respiratory Physiology. 8th ed. Oxford: Elsevier; 2017
    Google Scholar
  • 22 Janssens JP, Pache JC, Nicod LP. Physiological changes in respiratory function associated with ageing. Eur Respir J 1999; 13 (01) 197-205
    CrossrefPubMedGoogle Scholar
  • 23 Dantzker DR, Lynch JP, Weg JG. Depression of cardiac output is a mechanism of shunt reduction in the therapy of acute respiratory failure. Chest 1980; 77 (05) 636-642
    CrossrefPubMedGoogle Scholar
  • 24 Fredén F, Cigarini I, Mannting F, Hagberg A, Lemaire F, Hedenstierna G. Dependence of shunt on cardiac output in unilobar oleic acid edema. Distribution of ventilation and perfusion. Intensive Care Med 1993; 19 (04) 185-190
    CrossrefPubMedGoogle Scholar
  • 25 Hedenstierna G, Sandhagen B. Assessing dead space. A meaningful variable?. Minerva Anestesiol 2006; 72 (06) 521-528
    PubMedGoogle Scholar
  • 26 Pesenti A, Riboni A, Marcolin R, Gattinoni L. Venous admixture (Qva/Q) and true shunt (Qs/Qt) in ARF patients: effects of PEEP at constant FIO2. Intensive Care Med 1983; 9 (06) 307-311
    CrossrefPubMedGoogle Scholar
  • 27 Chuang ML, Hsieh BY, Lin IF. Resting dead space fraction as related to clinical characteristics, lung function, and gas exchange in male patients with chronic obstructive pulmonary disease. Int J Gen Med 2021; 14: 169-177
    CrossrefPubMedGoogle Scholar
  • 28 Aubier M, Murciano D, Milic-Emili J. et al. Effects of the administration of O2 on ventilation and blood gases in patients with chronic obstructive pulmonary disease during acute respiratory failure. Am Rev Respir Dis 1980; 122 (05) 747-754
    CrossrefPubMedGoogle Scholar
  • 29 Nuckton TJ, Alonso JA, Kallet RH. et al. Pulmonary dead-space fraction as a risk factor for death in the acute respiratory distress syndrome. N Engl J Med 2002; 346 (17) 1281-1286
    CrossrefPubMedGoogle Scholar
  • 30 Kallet RH, Lipnick MS. End-tidal-to-arterial pco2 ratio as signifier for physiologic dead-space ratio and oxygenation dysfunction in acute respiratory distress syndrome. Respir Care 2021; 66 (02) 263-268
    CrossrefPubMedGoogle Scholar
  • 31 Enghoff H. Volumen inefficax. Bemerkungen zur Frage des schädlichen Raumes. Upsala Lak Forhandl 1938; 44: 191-218
    PubMedGoogle Scholar
  • 32 Morrell NW, Nijran KS, Biggs T, Seed WA. Magnitude and time course of acute hypoxic pulmonary vasoconstriction in man. Respir Physiol 1995; 100 (03) 271-281
    CrossrefPubMedGoogle Scholar
  • 33 Morrell NW, Nijran KS, Biggs T, Seed WA. Regional matching of ventilation and perfusion during lobar bronchial occlusion in man. Clin Sci (Lond) 1995; 88 (02) 179-184
    CrossrefPubMedGoogle Scholar
  • 34 Sylvester JT, Shimoda LA, Aaronson PI, Ward JP. Hypoxic pulmonary vasoconstriction. Physiol Rev 2012; 92 (01) 367-520
    CrossrefPubMedGoogle Scholar
  • 35 Arai TJ, Henderson AC, Dubowitz DJ. et al. Hypoxic pulmonary vasoconstriction does not contribute to pulmonary blood flow heterogeneity in normoxia in normal supine humans. J Appl Physiol 2009; 106 (04) 1057-1064
    CrossrefPubMedGoogle Scholar
  • 36 Frostell CG, Blomqvist H, Hedenstierna G, Lundberg J, Zapol WM. Inhaled nitric oxide selectively reverses human hypoxic pulmonary vasoconstriction without causing systemic vasodilation. Anesthesiology 1993; 78 (03) 427-435
    CrossrefPubMedGoogle Scholar
  • 37 Naeije R, Brimioulle S. Physiology in medicine: importance of hypoxic pulmonary vasoconstriction in maintaining arterial oxygenation during acute respiratory failure. Crit Care 2001; 5 (02) 67-71
    CrossrefPubMedGoogle Scholar
  • 38 Petersson J, Glenny RW. Gas exchange and ventilation-perfusion relationships in the lung. Eur Respir J 2014; 44 (04) 1023-1041
    CrossrefPubMedGoogle Scholar
  • 39 Ranieri VM, Rubenfeld GD, Thompson BT. et al; ARDS Definition Task Force. Acute respiratory distress syndrome: the Berlin Definition. JAMA 2012; 307 (23) 2526-2533
    PubMedGoogle Scholar
  • 40 Wagner PD. The physiological basis of pulmonary gas exchange: implications for clinical interpretation of arterial blood gases. Eur Respir J 2015; 45 (01) 227-243
    CrossrefPubMedGoogle Scholar
  • 41 Aboab J, Louis B, Jonson B, Brochard L. Relation between PaO2/FIO2 ratio and FIO2: a mathematical description. Intensive Care Med 2006; 32 (10) 1494-1497
    CrossrefPubMedGoogle Scholar
  • 42 Gowda MS, Klocke RA. Variability of indices of hypoxemia in adult respiratory distress syndrome. Crit Care Med 1997; 25 (01) 41-45
    CrossrefPubMedGoogle Scholar
  • 43 Kreit JW. Volume capnography in the intensive care unit: physiological principles, measurements, and calculations. Ann Am Thorac Soc 2019; 16 (03) 291-300
    PubMedGoogle Scholar
  • 44 Sinha P, Fauvel NJ, Singh S, Soni N. Ventilatory ratio: a simple bedside measure of ventilation. Br J Anaesth 2009; 102 (05) 692-697
    CrossrefPubMedGoogle Scholar
  • 45 Maj R, Palermo P, Gattarello S. et al. Ventilatory ratio, dead space, and venous admixture in acute respiratory distress syndrome. Br J Anaesth 2023; 130 (03) 360-367
    CrossrefPubMedGoogle Scholar
  • 46 Guntheroth WG, Luchtel DL, Kawabori I. Pulmonary microcirculation: tubules rather than sheet and post. J Appl Physiol 1982; 53 (02) 510-515
    CrossrefPubMedGoogle Scholar
  • 47 Rahn H, Fenn WO. Graphical Analysis of the Respiratory Gas Exchange: The O2 CO2 Diagram. Bethseda, MD: American Physiological Society; 1955
    Google Scholar
  • 48 Benatar SR, Hewlett AM, Nunn JF. The use of iso-shunt lines for control of oxygen therapy. Br J Anaesth 1973; 45 (07) 711-718
    CrossrefPubMedGoogle Scholar