Steady-State Cardiovascular Regulation and the General Equation of the Circulation
- Paper number
IAC-08.A1.2.7
- Author
Dr. Ronald J. White, South Dakota School of Mines & Technology, United States
- Year
2008
- Abstract
A class of steady-state compartmental models of the circulation is examined and it is shown that the mathematical problem for this model class involves a single dimensionless equation of the form Z = ? + ? log[(1-Z)/Z] where ? and ? are new parameters related to the physiological parameters of the system and Z is proportional to the cardiac output. This result holds regardless of the number and arrangement of compartments within the model itself or of the number of physio¬logical parameters the model contains. This equation, termed the general equation of the circulation, is examined and the particular case of a five-compartment model with parallel visceral and peripheral flows, adjustable intrathoracic and abdominal pressures, and 25 physio¬logical parameters is used to illustrate the functioning of the model. Examples are provided to demonstrate the interplay among the model's parameters and the functioning of the model in various states. In particular, it is shown how relaxation of abdominal compression by 4 mm Hg and reduction of intrathoracic pressure by a like amount leads to a condition much like the rapid, initial response to weightlessness: a headward fluid shift, a reduction of central venous pressure, a small change in arterial pressure and an increase in cardiac output.
- Abstract document
- Manuscript document
(absent)