A mathematical model of ventilation response to inhaled carbon monoxide, based on the work of James H. Stuhmiller and Louise M. Stuhmiller [2005, JAP, 98, 2033-2044] and developed by Raymond Yakura as a final project for BIOEN 589, University of Washington.

Description

 A comprehensive mathematical model describing the respiration, circulation, oxygen metabolism, 
 and ventilatory control was assembled for the purpose of predicting acute ventilation changes 
 from exposure to carbon monoxide in both humans and animals. This Dynamic Physiological Model 
 is based on previously published work, reformulated, extended, and combined into a single model. 
 Model parameters are determined from literature values, fitted to experimental data, or 
 allometrically scaled between species. The model reaffirms the role of brain hypoxia on 
 hyperventilation during carbon monoxide exposures. Improvement in the estimation of total 
 ventilation, through a more complete knowledge of ventilation control mechanisms, and validated 
 by animal data, will increase the accuracy of inhalation toxicology estimates. 

 Introduction to the model:
 With CO acute inhalation, hyperventilation first results and followed by 
 a subsequent ventilation depression.  Hyperventilation is caused by hypoxia &
 increased CO2 that activates the peripheral chemoreceptors.  Then, ventilation 
 depression is caused by generation of lactic acid in the brain and by decreased 
 brain activity.  A buildup of carboxyhemoglobin with reduction in oxygen 
 delivery to the brain leads to anaerobic glycolysis and build up of lactate.

 The model consists of 6 subsets: 
      (1) RESPIRATION SYSTEM which incompasses the total ventilation and 
          effects of dead space and humidification.
      (2) VENTILATION which incompasses the chemoreceptor response, 
          brain activity response, and the combined ventilatory response
      (3) CIRCULATORY SYSTEM which incompasses the mass balance equations 
          for O2, CO2 and CO,
      (4) BLOOD CHEMISTRY which incompasses the hemoglobin saturation, 
          O2/CO partition, acid-base balance, and CO2 dissociation,
      (5) CARDIAC OUTPUT which incompasses the blood flow to the brain 
          increases during hypoxia,
      (6) METABOLIC SYSTEM which incompasses the oxygen metabolism, oxygen 
          transfer to the brain, lactic acid generation, and anaerobic limit, 	

• Powerpoint presentation on model by Raymond Yakura519 KB

Equations

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.