A compartmental model for oxygen transport in brain microcirculation |
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Authors: | Maithili Sharan M D Jones Jr R C Koehler R J Traystman Dr A S Popel |
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Institution: | (1) Present address: Gynecology and Obstetrics, Johns Hopkins University, 21205 Baltimore, MD;(2) Department of Biomedical Engineering School of Medicine, Johns Hopkins University, 21205 Baltimore, MD;(3) Department of Pediatrics (Eudowood Neonatal Pulmonary Division), Johns Hopkins University, 21205 Baltimore, MD;(4) Department of Anesthesiology/Critical Care Medicine Johns Hopkins University, 21205 Baltimore, MD |
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Abstract: | A compartmental model is formulated for oxygen transport in the cerebrovascular bed of the brain. The model considers the
arteriolar, capillary and venular vessels. The vascular bed is represented as a series of compartments on the basis of blood
vessel diameter. The formulation takes into account such parameters as hematocrit, vascular diameter, blood viscosity, blood
flow, metabolic rate, the nonlinear oxygen dissociation curve, arterial PO2, P50 (oxygen tension at 50% hemoglobin saturation with O2) and carbon monoxide concentration. The countercurrent diffusional exchange between paired arterioles and venules is incorporated
into the model. The model predicts significant longitudinal PO2 gradients in the precapillary vessels. However, gradients of hemoglobin saturation with oxygen remain fairly small. The longitudinal
PO2 gradients in the postcapillary vessels are found to be very small. The effect of the following variables on tissue PO2 is studied: blood flow, PO2 in the arterial blood, hematocrit, P50, concentration of carbon monoxide, metabolic rate, arterial diameter, and the number of perfused capillaries. The qualitative
features of PO2 distrbution in the vascular network are not altered with moderate variation of these parameters. Finally, the various types
of hypoxia, namely hypoxic, anemic and carbon monoxide hypoxia, are discussed in light of the above sensitivity analysis. |
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Keywords: | Oxygen transport Microcirculation Cerebral circulation Carbon monoxide Mathematical model Computer simulation |
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