Adv Exp Med Biol
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Comparative Study
Determination of the PCO2-dependent component of the H+ concentration in venous and arterial blood plasma.
In normal venous blood plasma, the regression line of [H+] plotted against the PCO2 was linear against the square root of PCO2. Sequential measurements in venous and arterial blood of PCO2 and [H+] showed that the venous-arterial (V-A) difference in [H+] was linearly related to the V-A difference in the square root of PCO2, the regression line having the same slope as that of the venous [H+] plotted against the square root of PCO2. ⋯ The PCO2-independent component, delta [H+], can then be given by subtracting [H+]* from the measured [H+]. The delta [H+] in venous blood agreed well with that in arterial blood with a correlation coefficient of 0.99, supporting the validity of the value of [H+]*.
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The oxygen tension (PO2) in the rat kidney was studied by modified Clark microelectrodes. Changes in PO2 were measured in the renal cortex and outer medulla after intravenous injections of the X-ray contrast medium (CM) diatrizoate, 370 mg iodine/mg body weight. ⋯ In the medulla PO2 decreased significantly (from 34 +/- 6 to 20 +/- 4 mm Hg). Ringer's solution did not induce any changes.
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We describe a new derived hemodynamic oxygenation parameter, the S factor (S). The factor is based on oxygen delivery and oxygen consumption and can range from -3 to 1. It allows simplified mathematical modeling of clinical problems of oxygen transport and can be applied to many clinical situations. ⋯ Thus, the change in OER from 'normal state' to anaerobic threshold is 0.3 (0.55-0.25) and the change in S is 1.2. This represents a four-fold increase. Four examples of mathematical modeling of global problems of oxygen transport using the S factor are described below.