Respiration physiology
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Respiration physiology · Jan 1986
The rate of oxygen release and its effect on capillary O2 tension: a mathematical analysis.
The time required by the red blood cells (RBC) to release the O2 needed by the tissues may be rate-limiting under conditions of reduced O2 supply (DO2). A time-dependent mathematical model of capillary O2 transport is developed to explore the effect of RBC deoxygenation kinetics on the intracapillary plasma PO2. The tissue capillaries are represented by a series of perfectly mixed compartments. ⋯ The discrepancy in PO2 profiles is magnified by anemia, [( Hemoglobin] = 5 g/dl), and hypoxemia, (PaO2 = 25 Torr). For these conditions of severe DO2 reduction, the end-capillary PO2 is significantly less than the venous PO2. These results suggest that (1) the kinetics of RBC deoxygenation can play an important role in the delivery of O2 to the tissues, and (2) the venous PO2 is not always an accurate measure of the end capillary PO2.