A comparison of overall mathematical models of the cardiovascular system for simulating response to orthostatic stresses.
Although numerous mathematical models of the cardiovascular system (CVS) have appeared in the literature  only a few of them are models of the entire system with detailed representation of the heart, the vasculature, and the control elements.  Like all models of biological systems, these models vary in complexity, and most of them are stimulus- specific.  Their ability to simulate with acceptable accuracy either responses over a wide range of the stimulus or responses to stimuli of similar kind has not been reported.  In this paper, three mathematical models of the CVS are examined in terms of their response to different orthostatic stresses, namely, lower body negative pressure (LBNP), head-up tilt, and blood loss.  The short-term orthostatic responses of the models are compared to available experimental data.  The models are:  (i) Croston and Fitzjerrell's for study of  LBNP and head-up tilt response,  (ii) Jaron et al.'s for study of +Gz response, and  (iii) Pullen's for simulation of response to blood loss.  We will henceforth refer to these models by the letters C, J, and P, respectively.
Karam
E H
EH
Space Biomedical Research Institute, NASA Johnson Space Center, Houston, TX 77058.
Srinivasan
R S
RS
Charles
J B
JB
D006470:Hemorrhage / Q000503:physiopathology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology*; D008150:Lower Body Negative Pressure / Q000009:adverse effects*; D008955:Models, Cardiovascular; D011187:Posture