Oxygen and carbon dioxide transport: the dissociation curve, Bohr and Haldane effects
Calculating oxygen content and delivery, reading the dissociation curve and what shifts it, the Bohr and Haldane effects, the three forms of CO2 carriage and the chloride shift, and why carbon monoxide, methaemoglobin and anaemia leave the PaO2 normal.
Tier 1Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Almost all oxygen in blood is bound to haemoglobin. Content depends on Hb and saturation; PaO2 matters mostly through saturation.
- The sigmoid curve keeps saturation high across a wide range of PaO2 and unloads oxygen steeply at tissue PO2.
- Bohr effect: CO2 and acid in tissues help release oxygen. Haldane effect: oxygen in the lungs helps release CO2.
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Sources
- West's Respiratory Physiology: The Essentials (11th ed.)Wolters Kluwer (West and Luks, 2020), 2020
- Hoffbrand's Essential Haematology (8th ed.)Wiley-Blackwell (Hoffbrand and Steensma, 2019), 2019
- Thoracic Society of Australia and New Zealand position statement on acute oxygen use in adults: 'Swimming between the flags'AU/NZRespirology (Barnett et al., 2022;27:262-276), 2022
- Practice recommendations in the diagnosis, management, and prevention of carbon monoxide poisoningAmerican Journal of Respiratory and Critical Care Medicine (Hampson et al., 2012;186:1095-1101), 2012
- Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trialAU/NZBMJ (Austin et al., 2010;341:c5462), 2010
- Last updated
- 14 November 2026
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