A Simple Cardiovascular Model for the Study of Hemorrhagic Shock
Table 2
Model parameters.
Parameter
Units
Meaning
min
Starting time for numerical integration
min
Final time for numerical integration
min
Time integration step
min
Starting time of hemorrhage
min
End time of hemorrhage
L
Ventricular volume end-diastolic at zero filling pressure
mmHg
Passive empirical ventricular pressure
/L
Constant characterizing the passive empirical pressure/volume relationship
Hydraulic resistance opposing ventricular filling
Compliance of arterial compartment
Compliance of venous compartment
L
Arterial unstressed volume at which the pressure induced by wall tension is 0 mmHg
/min
First-order low-pass cut-off frequency (determining the time constant of the baroreflex response)
mmHg
Deviation from set point in mmHg where SNA reaches 99% saturation either way (determining the shape and maximal slope of the logistic baroreflex nonlinearity)
mmHg
Set point for baroreflex regulation of mean arterial pressure
L
Total blood volume
L
External blood withdrawal from the venous compartment
/min
Heart rate minimum value
/min
Heart rate maximum value
mmHg
Preload recruitable stroke work minimum value
mmHg
Preload recruitable stroke work maximum value
Total peripheral/systemic vascular hydraulic resistance minimum value
Total peripheral/systemic vascular hydraulic resistance maximum value
L
Venous unstressed volume at which the pressure induced by wall tension is 0 mmHg minimum value
L
Venous unstressed volume at which the pressure induced by wall tension is 0 mmHg maximum value
#
Flag: -1 for closed loop; open reflex otherwise
L/min/mmHg
Rate of transcapillary refill per mmHg of difference between venous and interstitial pressure
L
Venous unstressed volume at which the pressure induced by wall tension is 0 mmHg minimum initial value
L
Venous unstressed volume at which the pressure induced by wall tension is 0 mmHg maximum initial value
mmHg
Arterial pressure initial value
#
Sympathetic nervous activity initial value
#
Stimulating output from baroreflex central processing initial value
L
Arterial volume at Tzero
L
Venous volume at Tzero
L
Venous unstressed volume at which the pressure induced by wall tension is 0 mmHg initial value
mmHg
Pressure in the central vein initial value
/min
Maximum initial value for heart rate
min
Duration of systole (ventricular contraction period of the cardiac cycle)
/min
Initial value for heart rate
min
Duration of diastole, endpoint of filling initial value
mmHg
Preload recruitable stroke work initial value
Total peripheral/systemic vascular hydraulic resistance initial value
Arterio-venous capillary blood flow initial value
Veno-arterial flow (cardiac output) initial value
L
End-systolic ventricular volume initial value
L
End-diastolic ventricular volume initial value
L
End-systolic ventricular volume tilde initial value
L
End-diastolic ventricular volume tilde initial value
mmHg
End-diastolic ventricular pressure initial value
mmHg
End-systolic ventricular pressure initial
External blood withdrawal from the venous compartment initial value
