// MODEL NUMBER: 0162
// MODEL NAME: Lung_RC_P
// SHORT DESCRIPTION: Single compliant tank driven by pleural pressure.
// This is the simplest lung model possible.
JSim v1.1
import nsrunit; unit conversion on;
math lung_rc { realDomain t sec;
real P(t) cmH2O; // APPLIED PRESSURE
real V(t) L; // LUNG VOLUME
real R = 2 cmH2O*sec/L, // Airway Resistance
C = 0.2 L/cmH2O, // Lung Compliance
FRC = 3 L, // Minimum LUNG VOLUME
freq = 10 1/min, // BREATHING FREQUENCY (breaths/min)
numCycles = 1, // NUMBER OF BREATHS TO RUN
PInit = - FRC/C, // INITIAL PRESSURE VALUE
PDelta = 2.5 cmH2O; // HALF AMPLITUDE CHANGE IN P
t.min = 0;
t.max = numCycles / freq;
t.delta = 1/(freq * 60); // 60 POINTS PER CYCLE
when (t=t.min) { V = 3.0746; }
P = PInit + PDelta*sin(2*PI*freq*t+PI/2) - PDelta;
V:t = -(P + V/C) / R;
}
/*
DETAILED DESCRIPTION:
This is the simplest lung model. The lung is a compliant sac
with resistance to filling, i.e. a single RC tank. The model
is driven by a sinusoidal function of "intrapleural" pressure.
Compliance is a chord compliance such that V--> 0 if P --> 0.
P, pressure represents intrapleural pressure, negative in
order to keep lung volume > zero. Parameter values are
approximate for a human adult.
SHORTCOMINGS/GENERAL COMMENTS:
- Specific inadequacies or next level steps
KEY WORDS: lung mechnanics, respiratory minute volume, elastance
pulmonary compliance, airway resistance, air flow, pleural pressure,
tidal volume, functional residual capacity FRC, total lung volume TLV,
Tutorial, air-blood gas exchange, gas buffers
REFERENCES:
Y.C. Fung; Biomechanics, Springer, 1993
REVISION HISTORY:
Original Author : JBB Date: 27/may/07
Revised by: BEJ Date:27jun11 : Update comment format
COPYRIGHT AND REQUEST FOR ACKNOWLEDGMENT OF USE:
Copyright (C) 1999-2011 University of Washington. From the National Simulation Resource,
Director J. B. Bassingthwaighte, Department of Bioengineering, University of Washington, Seattle WA 98195-5061.
Academic use is unrestricted. Software may be copied so long as this copyright notice is included.
This software was developed with support from NIH grant HL073598.
Please cite this grant in any publication for which this software is used and send an email
with the citation and, if possible, a PDF file of the paper to: staff@physiome.org.
*/