Oxygenation and Oxidation 



30 40 60 80 100 

 p0 2 in mm Hg " 



Figure 5. The percentage saturation of haemoglobin with oxygen 

 (or the percentage of oxyhaemoglobin of total pigment), or the 

 volumes per cent of oxygen absorbed by blood, as a function of two 

 variables, the p0 2 and the pC0 2 . A three-dimensional effect is 

 attained by originally plotting the oxygen dissociation curves on 

 separate graphs for each pC0 2 . The curves of oxygen saturation 

 at different pCO 2 and the grids connecting the curves at corresponding 

 percentages of saturation together form a complex curvilinear surface 

 on which the conditions in arterial A and venous V blood can be 

 adequately represented by the area between A and V. The ' point ' A 

 for arterial blood is defined by 98 per cent of oxyhaemoglobin at 

 p0 2 = 95 mm and pC0 2 = 41*5 mm, while V for venous blood is 

 defined by 11 per cent of oxyhaemoglobin at p0 2 = 40 mm and 

 pC0 2 — 47*5 mm (from the data of Lambertsen, Bunce and Drabkin ; 

 see Figure 4). The data of Bock et al 20 were used to plot the curves 

 at 3, 20, 40, and 80 mm pC0 2 . The curve at pC0 2 = was obtained 

 by extrapolation. The scale of volumes per cent 2 absorbed was 

 based on the fact that in blood containing 16 gm of haemoglobin per 

 100 ml (Drabkin^), the volumes per cent 2 absorbed at full saturation 

 would be 21*74 (21*44 volumes per cent in oxygenated haemoglobin, 

 0*3 volume per cent dissolved). 



particularly for the values of saturation along the steep part of the 

 curve it became essential to evaluate the magnitude of the various 

 changes owing to temperature differences and haemolysis. 



Our analyses indicated that the change in temperature form 37 to 

 27 °C had only a negligible effect on the percentage of Hb0 2 . At a 

 level of 98*4 per cent saturation, no change could be demonstrated at 

 38-0, 34-0 and 28-0°C ; at lower levels of saturation, such values as 

 74-6 per cent, at 37-8°C, and 74-8 per cent, at 27-2°C, were obtained. 



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