Guyton Model: pulmonary_fluid_dynamics
Catherine
Lloyd
Auckland Bioengineering Institute, University of Auckland
Model Status
This CellML model has been validated. Due to the differences between procedural code (in this case C-code) and declarative
languages (CellML), some aspects of the original model were not able to be encapsulated by the CellML model (such as the
damping of variables). This may effect the transient behaviour of the model, however the steady-state behaviour would remain
the same. The equations in this file and the steady-state output from the model conform to the results from the MODSIM program.
Model Structure
Arthur Guyton (1919-2003) was an American physiologist who became famous for his 1950s experiments in which he studied the physiology
of cardiac output and its relationship with the peripheral circulation. The results of these experiments challenged the conventional
wisdom that it was the heart itself that controlled cardiac output. Instead Guyton demonstrated that it was the need of the body
tissues for oxygen which was the real regulator of cardiac output. The "Guyton Curves" describe the relationship between right atrial
pressures and cardiac output, and they form a foundation for understanding the physiology of circulation.
The Guyton model of fluid, electrolyte, and circulatory regulation is an extensive mathematical model of human circulatory physiology,
capable of simulating a variety of experimental conditions, and contains a number of linked subsystems relating to circulation and its
neuroendocrine control.
This is a CellML translation of the Guyton model of the regulation of the circulatory system. The complete model consists of separate
modules each of which characterise a separate physiological subsystems. The Circulation Dynamics is the primary system, to which other
modules/blocks are connected. The other modules characterise the dynamics of the kidney, electrolytes and cell water, thirst and drinking,
hormone regulation, autonomic regulation, cardiovascular system etc, and these feedback on the central circulation model. The CellML code
in these modules is based on the C code from the programme C-MODSIM created by Dr Jean-Pierre Montani.
This particular CellML model describes a highly simplified analysis of pulmonary fluid dynamics. In general, the gel portion of the
pulmonary fluid is ignored, so that the pulmonary fluid volume (VPF) is in reality an approximation of the amount of fluid that is
relatively freely mobile. Though this fluid is called "interstitial fluid," it includes fluid in the respiratory passages. Likewise,
the pressure-volume curve of the pulmonary interstitium is highly simplified, as well as the control of lymph flow. Nevertheless, for
many purposes, this simplified analysis serves quite well.
model diagram
A systems analysis diagram for the full Guyton model describing circulation regulation.
model diagram
A schematic diagram of the components and processes described in the current CellML model.
There are several publications referring to the Guyton model. One of these papers is cited below:
Circulation: Overall Regulation, A.C. Guyton, T.G. Coleman, and H.J. Granger, 1972,
Annual Review of Physiology
, 34, 13-44. (A PDF version of the article are available to journal subscribers on the Annual Review of Physiology website.) PubMed ID: 4334846
Guyton
Pulmonary Fluid Dynamics
Description of Guyton pulmonary fluid dynamics module
2008-00-00 00:00
keyword
physiology
organ systems
cardiovascular circulation
pulmonary fluid dynamics
Guyton
This is a highly simplified analysis of pulmonary fluid dynamics. In general, the gel
portion of the pulmonary fluid is ignored, so that the pulmonary fluid volume (VPF) is
in reality an approximation of the amount of fluid that is relatively freely mobile.
Though this fluid is called "interstitial fluid," it includes fluid in the respiratory
passages. Likewise, the pressure-volume curve of the pulmonary interstitium is highly
simplified, as well as the control of lymph flow. Nevertheless, for many purposes, this
simplified analysis serves quite well.
Encapsulation grouping component containing all the components in the Pulmonary Fluid Dynamics Model.
The inputs and outputs of the Pulmonary Fluid Dynamics Model must be passed by this component.
PD1, PD2, PD2A, and PD3:
Calculation of pulmonary capillary pressure (PCP) from the pulmonary arterial
pressure (PPA) and left atrial pressure (PLA), and also from the vascular
resistances in the arterial (RPA) and venous (RPV) sides of the pulmonary
capillaries. The arterial resistance is set to be 1.6 times the venous
resistance.
PD1, PD2, PD2A, and PD3:
Calculation of pulmonary capillary pressure (PCP) from the pulmonary arterial
pressure (PPA) and left atrial pressure (PLA), and also from the vascular
resistances in the arterial (RPA) and venous (RPV) sides of the pulmonary
capillaries. The arterial resistance is set to be 1.6 times the venous
resistance.
$\mathrm{PCP}=\frac{(\mathrm{PPA}-\mathrm{PLA})\mathrm{RPV}}{\mathrm{RPV}+\mathrm{RPA}}+\mathrm{PLA}$
PD4:
The pressure gradient across the pulmonary capillary membrane (PGRPCM) is equal
to the pulmonary capillary pressure (PCP), plus the colloid osmotic pressure of
the pulmonary interstitial fluid (POS), minus the pulmonary interstitial fluid
pressure (PPI), minus the plasma colloid osmotic pressure (PPC).
PD5:
Rate of filtration of fluid outward through the pulmonary capillary membranes
into the interstitium (PFI) is equal to the pressure gradient across the
pulmonary capillary membrane (PGRPCM) times the pulmonary capillary filtration
coefficient (CPF).
PD4:
The pressure gradient across the pulmonary capillary membrane (PGRPCM) is equal
to the pulmonary capillary pressure (PCP), plus the colloid osmotic pressure of
the pulmonary interstitial fluid (POS), minus the pulmonary interstitial fluid
pressure (PPI), minus the plasma colloid osmotic pressure (PPC).
PD5:
Rate of filtration of fluid outward through the pulmonary capillary membranes
into the interstitium (PFI) is equal to the pressure gradient across the
pulmonary capillary membrane (PGRPCM) times the pulmonary capillary filtration
coefficient (CPF).
$\mathrm{PFI}=(\mathrm{PCP}-\mathrm{PPI}+\mathrm{POS}-\mathrm{PPC})\mathrm{CPF}$
PD5A, PD5B, and PD5C:
The rate of change of the fluid volume in the lungs (DFP) is equal to the rate
of filtration of fluid out of the pulmonary capillary membranes (PFI), minus the
rate of return of fluid to the circulation from the pulmonary interstitium by way
of the pulmonary lymphatics (PLF). Blocks 5B and 5C are computational blocks for
preventing oscillation and for preventing overshoot of the iteration. The damping
factor (Z) is used at multiple points in the model.
PD6:
Calculation of the volume of free fluid in the pulmonary interstitium (and
respiratory passageways) (VPF) by integrating the rate of change of the free fluid
in the lungs (DFP).
NB: - Damping in PD5B has been removed so that DFP = DFZ.
- PD5C has been rearranged so that "if" statement is dependent on VPF which may alter
the DFP output. (DFP IMPORTED INTO CP10 - Capillary Dynamics! CHECK THIS!!!).
PD5A, PD5B, and PD5C:
The rate of change of the fluid volume in the lungs (DFP) is equal to the rate
of filtration of fluid out of the pulmonary capillary membranes (PFI), minus the
rate of return of fluid to the circulation from the pulmonary interstitium by way
of the pulmonary lymphatics (PLF). Blocks 5B and 5C are computational blocks for
preventing oscillation and for preventing overshoot of the iteration. The damping
factor (Z) is used at multiple points in the model.
NB: - Damping in PD5B has been removed so that DFP = DFZ.
- PD5C has been rearranged so that "if" statement is dependent on VPF which may alter
the DFP output. (DFP IMPORTED INTO CP10 - Capillary Dynamics! CHECK THIS!!!).
PD5A, PD5B, and PD5C:
The rate of change of the fluid volume in the lungs (DFP) is equal to the rate
of filtration of fluid out of the pulmonary capillary membranes (PFI), minus the
rate of return of fluid to the circulation from the pulmonary interstitium by way
of the pulmonary lymphatics (PLF). Blocks 5B and 5C are computational blocks for
preventing oscillation and for preventing overshoot of the iteration. The damping
factor (Z) is used at multiple points in the model.
NB: - Damping in PD5B has been removed so that DFP = DFZ.
- PD5C has been rearranged so that "if" statement is dependent on VPF which may alter
the DFP output. (DFP IMPORTED INTO CP10 - Capillary Dynamics! CHECK THIS!!!).
PD5A, PD5B, and PD5C:
The rate of change of the fluid volume in the lungs (DFP) is equal to the rate
of filtration of fluid out of the pulmonary capillary membranes (PFI), minus the
rate of return of fluid to the circulation from the pulmonary interstitium by way
of the pulmonary lymphatics (PLF). Blocks 5B and 5C are computational blocks for
preventing oscillation and for preventing overshoot of the iteration. The damping
factor (Z) is used at multiple points in the model.
NB: - Damping in PD5B has been removed so that DFP = DFZ.
- PD5C has been rearranged so that "if" statement is dependent on VPF which may alter
the DFP output. (DFP IMPORTED INTO CP10 - Capillary Dynamics! CHECK THIS!!!).
PD6:
Calculation of the volume of free fluid in the pulmonary interstitium (and
respiratory passageways) (VPF) by integrating the rate of change of the free fluid
in the lungs (DFP).
$\mathrm{DFZ}=\mathrm{PFI}-\mathrm{PLF}\mathrm{DFP}=\mathrm{DFZ}\frac{d \mathrm{VPF1}}{d \mathrm{time}}=\mathrm{DFP}\mathrm{VPF}=\begin{cases}0.001 & \text{if $\mathrm{VPF1}< 0.001$}\\ \mathrm{VPF1} & \text{otherwise}\end{cases}$
PD10 and PD11:
Curve-fitting blocks to calculate the pulmonary interstitial fluid pressure (PPI)
from the pulmonary interstitial fluid volume (VPF).
PD10 and PD11:
Curve-fitting blocks to calculate the pulmonary interstitial fluid pressure (PPI)
from the pulmonary interstitial fluid volume (VPF).
$\mathrm{PPI}=2-\frac{0.15}{\mathrm{VPF}}$
PD15, PD15A, and PD15B:
The rate of change of the total quantity of protein in the pulmonary interstitium (PPD)
is equal to the rate of influx of protein into the interstitium as a result of protein
leakage through the pulmonary capillary membrane (PPN) minus the rate of return of protein
to the circulation from the interstitium by way of the lymphatics (PPO). Blocks 15A and
15B are computational blocks for the purpose of preventing overshoot of an iteration and
for preventing oscillation. The factor (Z) is a damping factor that is used widely
throughout the model.
NB: - Damping in PF15A has been removed so that PPD = PPZ.
- PD15B has been rearranged so that "if" statement is dependent on PPR which may alter
the PPD output. (PPD IMPORTED INTO CP33 - Capillary Dynamics! CHECK THIS!!!).
PD16:
The total quantity of protein in the pulmonary interstital free fluid (PPR) is calculated
by integrating with respect to time the rate of change of protein in the pulmonary
interstitium (PPD).
PD17:
The concentration of protein in the pulmonary interstitium (CPN) is equal to the total
quantity of protein in the interstitium (PPR) divided by the volume of interstitial
fluid (VPF).
PD15, PD15A, and PD15B:
The rate of change of the total quantity of protein in the pulmonary interstitium (PPD)
is equal to the rate of influx of protein into the interstitium as a result of protein
leakage through the pulmonary capillary membrane (PPN) minus the rate of return of protein
to the circulation from the interstitium by way of the lymphatics (PPO). Blocks 15A and
15B are computational blocks for the purpose of preventing overshoot of an iteration and
for preventing oscillation. The factor (Z) is a damping factor that is used widely
throughout the model.
NB: - Damping in PF15A has been removed so that PPD = PPZ.
- PD15B has been rearranged so that "if" statement is dependent on PPR which may alter
the PPD output. (PPD IMPORTED INTO CP33 - Capillary Dynamics! CHECK THIS!!!).
PD15, PD15A, and PD15B:
The rate of change of the total quantity of protein in the pulmonary interstitium (PPD)
is equal to the rate of influx of protein into the interstitium as a result of protein
leakage through the pulmonary capillary membrane (PPN) minus the rate of return of protein
to the circulation from the interstitium by way of the lymphatics (PPO). Blocks 15A and
15B are computational blocks for the purpose of preventing overshoot of an iteration and
for preventing oscillation. The factor (Z) is a damping factor that is used widely
throughout the model.
NB: - Damping in PF15A has been removed so that PPD = PPZ.
- PD15B has been rearranged so that "if" statement is dependent on PPR which may alter
the PPD output. (PPD IMPORTED INTO CP33 - Capillary Dynamics! CHECK THIS!!!).
PD15, PD15A, and PD15B:
The rate of change of the total quantity of protein in the pulmonary interstitium (PPD)
is equal to the rate of influx of protein into the interstitium as a result of protein
leakage through the pulmonary capillary membrane (PPN) minus the rate of return of protein
to the circulation from the interstitium by way of the lymphatics (PPO). Blocks 15A and
15B are computational blocks for the purpose of preventing overshoot of an iteration and
for preventing oscillation. The factor (Z) is a damping factor that is used widely
throughout the model.
NB: - Damping in PF15A has been removed so that PPD = PPZ.
- PD15B has been rearranged so that "if" statement is dependent on PPR which may alter
the PPD output. (PPD IMPORTED INTO CP33 - Capillary Dynamics! CHECK THIS!!!).
PD16:
The total quantity of protein in the pulmonary interstital free fluid (PPR) is calculated
by integrating with respect to time the rate of change of protein in the pulmonary
interstitium (PPD).
PD17:
The concentration of protein in the pulmonary interstitium (CPN) is equal to the total
quantity of protein in the interstitium (PPR) divided by the volume of interstitial
fluid (VPF).
$\mathrm{PPZ}=\mathrm{PPN}-\mathrm{PPO}\mathrm{PPD}=\mathrm{PPZ}\frac{d \mathrm{PPR1}}{d \mathrm{time}}=\mathrm{PPD}\mathrm{PPR}=\begin{cases}0.025 & \text{if $\mathrm{PPR1}< 0.025$}\\ \mathrm{PPR1} & \text{otherwise}\end{cases}\mathrm{CPN}=\frac{\mathrm{PPR}}{\mathrm{VPF}}$
PD18:
The colloid osmotic pressure of the pulmonary interstitial fluid (POS) is equal to
the concentration of protein in the pulmonary interstitium (CPN) times a constant.
PD18:
The colloid osmotic pressure of the pulmonary interstitial fluid (POS) is equal to
the concentration of protein in the pulmonary interstitium (CPN) times a constant.
$\mathrm{POS}=\mathrm{CPN}\times 0.4$
PD19 and PD20:
The rate of leakage of protein through the pulmonary capillary membrane into the pulmonary
interstitium (PPN) is equal to the concentration of protein in the plasma (CPP), minus the
concentration of protein in the pulmonary interstitium (CPN) times a constant.
PD19 and PD20:
The rate of leakage of protein through the pulmonary capillary membrane into the pulmonary
interstitium (PPN) is equal to the concentration of protein in the plasma (CPP), minus the
concentration of protein in the pulmonary interstitium (CPN) times a constant.
$\mathrm{PPN}=(\mathrm{CPP}-\mathrm{CPN})\times 0.000225$
PD12 and PD13:
Curve-fitting blocks to calculate the rate of pulmonary lymph flow (PLF) from the
pulmonary interstitial fluid pressure (PPI).
PD14:
Rate of return of protein from the pulmonary interstitium to the circulation in
the pulmonary lymph (PPO) is equal to the concentration of protein in the
pulmonary interstitial fluid (CPN) times the rate of pulmonary lymph flow (PLF).
PD12 and PD13:
Curve-fitting blocks to calculate the rate of pulmonary lymph flow (PLF) from the
pulmonary interstitial fluid pressure (PPI).
PD14:
Rate of return of protein from the pulmonary interstitium to the circulation in
the pulmonary lymph (PPO) is equal to the concentration of protein in the
pulmonary interstitial fluid (CPN) times the rate of pulmonary lymph flow (PLF).
$\mathrm{PLF}=(\mathrm{PPI}+11)\times 0.0003\mathrm{PPO}=\mathrm{PLF}\mathrm{CPN}$