Model: SIMVOL-multi-organ recirculating system with shunt

TABLE OF CONTENTS

Parameters

Output Variables

Diagram

Model demonstrations with parameter sets

1. IMPORTANT !!! To run a demonstration, enter "xhost +nsr.bioeng.washington.edu" in one of your windows to allow the demonstration program to open windows on your machine !!!

2. Parameters

SIMVOL is parameterized as follows.

Table 1. SIMVOL Parameters

Parameter

Description

Units

Cin

Input concentration parameters

as specified

mass A

Mass of organ A

g

fr mass Ac

The fraction of mass A being modeled with CTEX (compartment tissue exchange model)

dimensionless

RATIO A

The ratio of flow/mass of

CTEX/(CTEX+BTEX) for organ A

dimensionless

FLOW TOT

Total flow

ml/min

fr Shunt

The fraction of the flow being shunted around organ B

dimensionless

mass B

Mass of organ B

g

fr mass Bc

The fraction of mass A being modeled with CTEX (compartment tissue exchange model)

dimensionless

RATIO B

The ratio of flow/mass of

CTEX/(CTEX+BTEX) for organ B

dimensionless

fr Clear

Fractional Clearance, the fraction of Cout removed each time step

 

dimensionless

Access to all input variables is via clicking the "INPUT" button on the main model page or by selecting "Inputs" under the "Parameters" menu.

3. Output Variables

Output variables are given by:

Table 2. SIMVOL Output Variables

Parameter

Description

Units

Cin

Input concentration waveform

molar (M)

Cin A

Input concentration to Organ A

Sum of Cin + C recirc

molar (M)

Cout Ac

Outflow concentration of Organ A (CTEX)

molar (M)

Cout Ab

Outflow concentration of Organ A (BTEX)

molar (M)

Cout A

Combined concentration outflow of organ A (CTEX+BTEX)

molar (M)

Cin B

Input concentration to Organ B

molar (M)

Cout Bc

Outflow concentration of Organ B (CTEX)

molar (M)

Cout Bb

Outflow concentration of Organ B (BTEX)

molar (M)

Cout B

Combined concentration outflow of organ B (CTEX+BTEX)

molar (M)

C shunt

Concentration shunted around organ B

molar (M)

Cout

Output concentration

Sum of Cout B and C shunt

molar (M)

C clear

Concentration cleared from system

C clear = Cout*fr Clear

molar (M)

C recirc

Concentration recirculation

Crecirc = Cout*(1 - fr Clear)

molar (M)

F/m Ac

Flow/mass for Organ A (CTEX)

ml/(min(g)

F/m Ab

Flow/mass for Organ A (BTEX)

ml/(min(g)

F/m Bc

Flow/mass for Organ B (CTEX)

ml/(min(g)

F/m Bb

Flow/mass for Organ B (BTEX)

ml/(min(g)

Flow noshunt

Flow into Organ B

Flow noshunt=FLOT TOT*(1 - fr Shunt)

ml/min

Q_ct_A

Quantity of material in Organ A (CTEX)

molar*ml

Q_bt_A

Quantity of material in Organ A (BTEX)

molar*ml

Q_ct&bt_A

Quantity of material in Organ A (CTEX+BTEX)

molar*ml

Q_ct_B

Quantity of material in Organ B (CTEX)

molar*ml

Q_bt_B

Quantity of material in Organ B (BTEX)

molar*ml

Q_ct&bt_B

Quantity of material in Organ B (CTEX+BTEX)

molar*ml

Q_A&B

Quantity of material in Organs A and B combined

molar*ml

Q_integral

integral of FLOW TOT*(Cin-C clear)*dt

molar*ml

 

Qintct_A

Quantity of material in Organ A (CTEX) by integral method

molar*ml

 

Qintbt_A

Quantity of material in Organ A (BTEX) by integral method

molar*ml

 

Qintct_B

Quantity of material in Organ B (CTEX) by integral method

molar*ml

 

Qintbt_B

Quantity of material in Organ B (BTEX) by integral method

molar*ml

 

Qrecirc

Amount of material recirculation back into the system in the next time step

molar*ml

 

To plot results, select "Plot Area 1" from the Results menu. Place the cursor in an unused box under Y-parameters and press the right mouse button to bring up a list of plottable parameters.

4. Diagram

 

 

 

5. Model demonstrations with parameter sets

The user should inspect the input parameters and the output curves. Output curves can be found under the Results button under Plot Area 1 and Plot Area 2.

The following parameter sets are can be demonstrated by clicking on them:

5.1. Figure 9.2 : Figure09.02.par

Run the model. Displacement of fluid from a well stirred chamber. Flow is 600 ml/min (10 ml/sec). Volume is 100 ml. Amount of material injected is 1 mmole. Numeric and analytic solutions are plotted.

5.2. Figure 9.3: Figure09.03.par

Run the model. Dilution into a pair of well stirred volumes. Time course of concentrations with pulse input when each of V1 and V2 are instaneously mixed. (Flow=10 ml/sec, V1=100ml, V2=200ml)

 

5.3. Figure 9.5: Figure09.05.par

Run the model. See output under Results: Plot Area 1. The response of the system when the solute is constrained to just the plasma space, compared to the solute entering the ISF space, with concentrations measured at the outflows of this two-organ "whole-body" model.

5.4. Figure 9.6: Figure09.06.par

Run the model. Tracer concentration-time courses under Results: Plot Area 1 for 4-organ, 3-tissue-region model analogous to that in Figure 9.5 (zero clearance). Each "organ" was composed of regions for plasma, ISF, and cells. An extracellular flow marker enters the former two regions only; tracer water enters all three regions.

5.5. Figure 9.7: Figure09.07.par

Run the model. Plasma concentratime time curves for plasma, extracellular flow, and water markers where there is tracer lost from the body and the clearance is 30%.

5.6. Figure 9.8: Figure09.08.par

Semilog plots of plasma concentrations of markers for plasma, ECF and water spaces when clearance is exactly 30% of the flow or "cardiac output" in the model used in Figure 9.6. All curves have a monoexponential tail.

5.7. Figure 9.9: Figure09.09

Semilog plot of plasma concentration time curves for a strictly intravascular marker which is gradually cleared from the circulation. The tails of the curves are fitted by a single exponential. The loss rate or clearance was set at 0, 5, 10, 15, and 20% of the whole body recirculation. Monoexponential curves fitting the "data" from 100 to 200 seconds extrapolate back to an apparent common intersection at negative time. The intercept at t=0 is lower with clearance > 0, and using its value, C(t=0) , gives overestimates of Vpl .

 


Home

Search the NSR web site.

Copyright © 2000, National Simulation Resource, University of Washington.

Contact garyr@nsr.bioeng.washington.edu with comments, questions, or critiques.