title: Numerical simulation of systemic O2 and CO2 exchange in a hyperbaric environment.
abstract: The process of gas exchange in systemic capillaries and its surrounding tissue is simulated numerically in a hyperbaric environment, taking into account the molecular diffusion, convection, saturation of haemoglobin with O2 and CO2, and the metabolic activity in the tissue. Krogh tissue-cylinder is used as a geometrical representation of the capillary-tissue system. The resulting system of non-linear governing equations together with the physiologically relevant boundary conditions is solved numerically. It is found that the concentration of oxygen decreases from the axis of the capillary to the tissue periphery whereas the concentration of carbon dioxide increases. It is shown that very little CO2 is transported radially. The location of the vulnerable region from the point of view of CO2 accumulation is found to be the rim (r = R2, z = L) situated at the periphery of the tissue near the venous end of the capillary. It is also found that accumulation of O2 decreases whereas that of CO2 increases in a hyperbaric environment. Finally, it is surmised that one of the reasons in causing discomfort among divers could be excessive accumulation of CO2 in the tissue.
authors.affiliation: Centre for Atmospheric Sciences, Indian Institute of Technology, Delhi Hauz Khas, New Delhi, India.
authors.forename: M
authors.initials: M
authors.lastname: Sharan
authors.forename: M P
authors.initials: MP
authors.lastname: Singh
authors.forename: R K
authors.initials: RK
authors.lastname: Saxena
authors.forename: I
authors.initials: I
authors.lastname: Sud
mesh_terms: D001692:Biological Transport; D002196:Capillaries / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism* / Q000633:toxicity; D004242:Diving; D008433:Mathematics; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism*; D010313:Partial Pressure
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen