Oxygen dissociation curve of the blood

In cases of metabolic acidosis due to circulatory collapse, the acidaemia confers some physiological advantage in that it causes a shift to the right of the oxygen dissociation curve of the blood (Chapter 6). This assists in the unloading of oxygen from blood to the tissues and to a slight extent counteracts the tissue hypoperfusion. 

Ascorbic acid appears to be toxic to certain tumor tissues however, it may increase the biological effectiveness of red blood cells by increasing the level of 2,3-diphosphoglycerate (30,31), 2,3-Diphosphoglycerate is essential to maintaining the normal oxygen dissociation curve of hemoglobin. This increase has been shown in vitro (30) and in vivo, in human subjects (31). 

There are many other events that can produce a significant reduction in the RBC mass and a subsequent decrease in the oxygen-carrying capacity of the blood. Normally, the blood volume is maintained at a relatively constant level hence, any process or event that causes a reduction in either RBCs or hemoglobin produces a condition known as an anemia. Anemias can also shift the oxyhemoglobin dissociation curve... 

Figure 27-3 A, Oxygen dissociation curves for human blood with different plasma pH, but constant PCO2 of 40mmHg, a 2,3-diphosphoglycerol concentration in erythrocytes of 5.0mmol/L, and temperature at 37 C. B, A Hill plot. Conditions are the same as in A. DPG, 2,3 diphosphog ycerol.

A 72-year-old woman with emphysema presents to the emergency room with fatigue and respiratory distress. Which set of arterial blood gas values below would represent her condition and reflect a shift of the hemoglobin oxygen dissociation curve to the right ... 

In the case where the blood flow is laminar, as within hollow-fiber oxygenators, the rates of blood oxygenation can be predicted on a theoretical basis. Due to the shape of the oxyhemoglobin dissociation curve and the fact that the oxygen partial... 

The partial pressure, Pq, of the oxygen in the blood (oxygen tension) is related to Sq by the oxygen dissociation curve (Fig. 2.11). The shape and position of this sigmoidal curve depend on the temperature, the hydrogen ion concentration and the concentration within the red cells of other ligands of haemoglobin... 

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