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DOI: 10.1055/s-0043-1770060
Gas Exchange in the Lung
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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 - hypercapniaPublikationsverlauf
Artikel online veröffentlicht:
10. Oktober 2023
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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
- 2 Weibel ER. What makes a good lung?. Swiss Med Wkly 2009; 139 (27–28): 375-386
- 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
- 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
- 5 Cruickshank S, Hirschauer N. The alveolar gas equation. Contin Educ Anaesth Crit Care Pain 2004; 4: 24-27
- 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
- 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
- 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
- 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
- 10 Hughes JM, Pride NB. In defence of the carbon monoxide transfer coefficient Kco (TL/VA). Eur Respir J 2001; 17 (02) 168-174
- 11 Glenny RW. Determinants of regional ventilation and blood flow in the lung. Intensive Care Med 2009; 35 (11) 1833-1842
- 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
- 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
- 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
- 15 Hlastala MP, Glenny RW. Vascular structure determines pulmonary blood flow distribution. News Physiol Sci 1999; 14: 182-186
- 16 Glenny RW, Polissar L, Robertson HT. Relative contribution of gravity to pulmonary perfusion heterogeneity. J Appl Physiol 1991; 71 (06) 2449-2452
- 17 Glenny RW, Robertson HT. Fractal properties of pulmonary blood flow: characterization of spatial heterogeneity. J Appl Physiol 1990; 69 (02) 532-545
- 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
- 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
- 20 West JB. Regional differences in gas exchange in the lung of erect man. J Appl Physiol 1962; 17: 893-898
- 21 Lumb AB. Nunn's Applied Respiratory Physiology. 8th ed. Oxford: Elsevier; 2017
- 22 Janssens JP, Pache JC, Nicod LP. Physiological changes in respiratory function associated with ageing. Eur Respir J 1999; 13 (01) 197-205
- 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
- 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
- 25 Hedenstierna G, Sandhagen B. Assessing dead space. A meaningful variable?. Minerva Anestesiol 2006; 72 (06) 521-528
- 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
- 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
- 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
- 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
- 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
- 31 Enghoff H. Volumen inefficax. Bemerkungen zur Frage des schädlichen Raumes. Upsala Lak Forhandl 1938; 44: 191-218
- 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
- 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
- 34 Sylvester JT, Shimoda LA, Aaronson PI, Ward JP. Hypoxic pulmonary vasoconstriction. Physiol Rev 2012; 92 (01) 367-520
- 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
- 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
- 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
- 38 Petersson J, Glenny RW. Gas exchange and ventilation-perfusion relationships in the lung. Eur Respir J 2014; 44 (04) 1023-1041
- 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
- 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
- 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
- 42 Gowda MS, Klocke RA. Variability of indices of hypoxemia in adult respiratory distress syndrome. Crit Care Med 1997; 25 (01) 41-45
- 43 Kreit JW. Volume capnography in the intensive care unit: physiological principles, measurements, and calculations. Ann Am Thorac Soc 2019; 16 (03) 291-300
- 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
- 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
- 46 Guntheroth WG, Luchtel DL, Kawabori I. Pulmonary microcirculation: tubules rather than sheet and post. J Appl Physiol 1982; 53 (02) 510-515
- 47 Rahn H, Fenn WO. Graphical Analysis of the Respiratory Gas Exchange: The O2 CO2 Diagram. Bethseda, MD: American Physiological Society; 1955
- 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