Model number

Hemoglobin CO2 saturation curve at varied levels of PO2 and pH. Temperature and 2,3-DPG concentration are assumed constant. Based on Dash 2010 paper.


Model to approximate CO2 saturation of hemoglobin (SHbCO2) is described here from the equilibrium binding of CO2 with hemoglobin inside RBCs. It is in the form of an invertible Hill-type equation with the apparent Hill coefficient KHbCO2 in the expression. SHbCO2 is dependent on the levels of O2 and CO2 partial pressures (PO2 and PCO2 ) and pH. The dependence on 2,3-DPG concentration and temperature in blood is assumed constant. Because of the mathematical simplicity and invertibility, these new formulas can be conveniently used in the modeling of simultaneous transport and exchange of O2 and CO2 in the alveoli-blood and blood-tissue exchange system.


The equations for this model may be viewed by running the JSim model applet and clicking on the Source tab at the bottom left of JSim's Run Time graphical user interface. The equations are written in JSim's Mathematical Modeling Language (MML). See the Introduction to MML and the MML Reference Manual. Additional documentation for MML can be found by using the search option at the Physiome home page.

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Dash RK and Bassingthwaighte JB.(Erratum Reprint of 2004 paper) Blood HbO2 and HbCO2 dissociation curves at varied O2, CO2, pH, 2,3-DPG and temperature levels. Ann Biomed Eng 38: 1683-1701, 2010.


Key terms
carbon dioxide
blood gases
Hill equation

Please cite in any publication for which this software is used and send one reprint to the address given below:
The National Simulation Resource, Director J. B. Bassingthwaighte, Department of Bioengineering, University of Washington, Seattle WA 98195-5061.

Model development and archiving support at provided by the following grants: NIH U01HL122199 Analyzing the Cardiac Power Grid, 09/15/2015 - 05/31/2020, NIH/NIBIB BE08407 Software Integration, JSim and SBW 6/1/09-5/31/13; NIH/NHLBI T15 HL88516-01 Modeling for Heart, Lung and Blood: From Cell to Organ, 4/1/07-3/31/11; NSF BES-0506477 Adaptive Multi-Scale Model Simulation, 8/15/05-7/31/08; NIH/NHLBI R01 HL073598 Core 3: 3D Imaging and Computer Modeling of the Respiratory Tract, 9/1/04-8/31/09; as well as prior support from NIH/NCRR P41 RR01243 Simulation Resource in Circulatory Mass Transport and Exchange, 12/1/1980-11/30/01 and NIH/NIBIB R01 EB001973 JSim: A Simulation Analysis Platform, 3/1/02-2/28/07.