Biomedical Systems

VisSim Tutorial Series

Biomedical Systems: Modeling and Simulation of Lung Mechanics and Ventilator Controls Design
Mike Borrello, Metran America, Inc.

VisSim Tutorial Series: Biomedical Systems: Modeling and Simulation of Lung Mechanics and Ventilator Controls Design

VisSim Tutorial Series
Biomedical Systems: Modeling and Simulation of Lung Mechanics and Ventilator Controls DesignCopyright ©1997 Visual Solutions, Inc.

All rights reserved. Trademarks VisSim, VisSim/C-Code, and VisSim/Real-TimePRO are trademarks of Visual Solutions.

Excerpted with permission from Modeling and Visual Simulation in Industry, A. Mulpur and P. Darnell, International Thomson Computer Press, Boston, MA, 1997. The information in this document is subject to change without notice and doesnot represent a commitment by Visual Solutions. Visual Solutions does not assume responsibility for errors that may appear in this document.

Other books in the VisSim Tutorial Series include:
• • • • •

Fundamentals of Mathematical Modeling and Simulation. Peter Darnell and Arun Mulpur, Visual Solutions, Inc. Heating, Ventilation and Air Conditioning (HVAC) Controls: Variable Air Volume(VAV) Systems. Nebil Ben-Aissa, Johnson Controls, Inc. Introduction to 6-DOF Simulation of Air Vehicles. Robert Josselson, ITT Aerospace Systems Group. Simulation of Communication Systems. Eugene Estinto, Eritek, Inc. Simulation of Motion Control Systems. William Erickson, Indramat-Rexroth.

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VisSim Tutorial Series: Biomedical Systems: Modeling and Simulation of Lung Mechanics andVentilator Controls Design

Table of Contents
Introduction ........................................................................................................... 1 Overview of a Ventilation System........................................................................ 1 Model Development .............................................................................................. 2
PatientCircuit .................................................................................................................3 Endotracheal Tube ..........................................................................................................4 Flow Valves....................................................................................................................5 Patient ResistiveAirways ...............................................................................................6 The Lung as an Elastic Compartment.............................................................................6 Respiratory Drive ...........................................................................................................7

Model Construction.............................................................................................. 8
Constructing the VisSim Block Diagram .......................................................................9 Model Simplification ......................................................................................................9

Using the Model inSimulation........................................................................... 10
Investigating More Complex Properties of the Lung/Ventilator Model.......................11

Programming VisSim for Embedded Applications ......................................... 12
Hardware-in-the-Loop Simulation................................................................................12 Aliasing and Filtering Measurements.......................................................................13 Verifying Real Time in VisSim ................................................................................13 Step Rate Selection Considerations ..........................................................................15 Using transferFunction Blocks .................................................................................15 Choice of Integration...