Relation between the Contact Time and Venous and Alveolar Pco2 at Rest
The simultaneous partial differential equations for diffusions of O2, CO2, and HCO 3 − ions in the red blood cell (RBC) were solved numerically, taking chemical reactions of Bohr- and Haldane-effects into account. The diffusion equations and the chemical reactions were computed alternatively in an increment time of 2 msec. After solving each of the three diffusion equations, the Po2, O2 saturation (S), Pco2, pH and HCO 3 − content were corrected by using the equations of Bohr- and Haldane-effects, and a modified Henderson-Hasselbalch equation (Kagawa and Mochizuki, 1984). The Bohr-shift was calculated from Hill’s equation by assuming its K value to be a function of the intracellular pH. The change in intracellular Pco2 due to the Haldane effect was also evaluated by means of the modified Henderson-Hasselbalch equation, in which the buffer value was taken as 44 mmol · 1(RBC)−1 · pH c −1 . The computed Pco2 profiles during the Haldane effect in a closed vessel was compatible wit the experimental data of Klocke (1973). The extracellular Po2 profile computed during the Bohr-off-shift in a closed system coincided well with the experimental data of Nakamura and Staub (1964) and Forster and Steen (1968).
KeywordsContact Time Diffusion Equation Rebreathing Method Lung Capillary Pulmonary Capillary Blood
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