VENTILATION AND PERFUSION MATCHING IN THE LUNG:

A computer model for teaching pulmonary physiology

 

VERSION 1.2
Please send any comments/suggestions to Dr. Martin Doerfler doerfm01@@popmail.med.nyu.edu
Send bug reports to Marc Waldman marc@@popmail.med.nyu.edu

Martin E. Doerfler, MD
Associate Professor of Clinical Medicine
Director, Critical Care Medicine
Division of Pulmonary / Critical Care Medicine
 
New York University Medical Center
Credits:
Created for the Hippocrates Project of the New York University School of Medicine by
Programming: Sulaiman Malik Carnegie Mellon University
Marc Waldman NYU Hippocrates Project
New York University Medical Center
Animations: Julio Garcia NYU Hippocrates Project
New York University Medical Center
Hippocrates Project Director: Martin Nachbar, MD Assoc. Prof. of Medicine and Microbiology
Director, Educational Computing
New York University Medical Center
 
Special thanks: To Barry Sorkin, RRT Division of Pulmonary / Critical Care Medicine, New York University Medical Center, for his invaluable suggestions and comments. Invitation to Collaborate:
We welcome collaboration on the development of new models and applications which use or are based on the models included at this web site. The code for the models has been intentionally placed in the open environment of JavaScript to facilitate the growth, accuracy, and utility of the models and applications derived therefrom. If, based on this work, you develop a useful model or application, we ask that acknowledgement of the original work be cited - e.g. Doerfler, M., VENTILATION AND PERFUSION MATCHING IN THE LUNG (http://endeavor.med.nyu.edu/research/gas-exchange/). If you wish to share your work please email us at doerfm01@@popmail.med.nyu.edu. Credit will be given for included materials in updated versions of the program. Ref.
 

This program has at it's core many of the routines and subroutines in:J.B West and P.D. Wagner; Pulmonary Gas Exchange in Bioengineering Aspects of the Lung. ed J.B. West pp. 361-454; Lung Biology in Health and Disease,vol 3, Marcel Dekker Inc. 1977

 

Introduction:

This program was developed as an interactive exercise for the teaching of Pulmonary Physiology to medical and graduate students. It is an advanced exercise that assumes that the students have a basic knowledge of the principals of gas exchange , the alveolar gas equation, and of the oxyhemoglobin saturation curve. It is ideally used as an adjunct to the Pulmonary section of a textbook of human physiology or (the author's preference) the CD-ROM of Interactive Physiology (Respiratory System, Andrea Salmi, Author), A..D.A.M. Software, Inc. and Benjamin Cumming Publishing, 1996.

Being written entirely in JavaScript, the program operation is not dependent on internet link capacity but on the speed of the host computer. It requires Netscape Navigator 3.0 or above and Shockwave (available from Macromedia) .There are 4 windows to simultaneously display during the operation of the program and the larger the monitor used the better. The program will run on older machines such as the Macintosh Quadra but runs best with newer faster machines using PowerPC or Pentium processors. The faster the better. (486 and older PCs have not been evaluated).

 
Operation:
In using the model the student first picks from the list of lung models. Four Ventilation/ Perfusion (V/Q) patterns have been created and the distribution of alveolar ventilation and perfusion are displayed:
1) The normal lung (Interpolated from John West's classic descriptions of the distribution of V/Q ratios in the normal lung in J.B. West RespiratoryPhysiology editions 1-5 )
2) An individual with many units with high V/Q or alveolar dead space (titled emphysema) ( Interpolated from Wagner, P.D. Dantzker, D.R., Dueck,R., Clausen, J.L. and West, J.B. Ventilation Perfusion Inequality in Chronic Obstructive Pulmonary Disease. J. Clin Invest 59:203-216, 1977)
3) An individual with areas of high V/Q, areas of low V/Q and areas of intrapulmonary shunt (titled COPD with acute bronchitis) ( Interpolated from Dantzker D.R. Chronic Obstructive Pulmonary Disease. New York,Churchill Livingstone 1983.)
4) An individual with a significant intrapulmonary shunt (titled Bronchial obstruction) (empirically created or made up )
5) A fifth option is available titled "User Defined" allowing the more experienced student (or faculty) to create their own V/Q distributions. The entries are percents and must add up to 1.0 for both V and Q. Once a "Model" has been chosen the student can then vary any of the variables in the left panels of the window. Default values have been chosen that represent a healthy person breathing room air at rest at sea level. The "Run" button is then clicked in the upper window and the program calculates the values for PO2, PCO2, O2 Content, CO2 content and R for each compartment, and a "results" window is generated that lists the pH, pCO2, pO2 and hemoglobin saturation of the arterial blood. The above compartment values are also displayed so that the student can see the mathematical contribution of each compartment to the exchange of O2 and CO2. Two animations are also generated, each in separate windows, labeled PO2 Animation and PCO2 Animation. The animations are color coded to allow visualization of the gas exchange in each of the twenty alveolar units.
We will be adding tutorials to the models over the ensuing months to guide beginning students through some of the major teaching points that are easily demonstrated by the program. For now, hopefully you will find this both educational and fun.
Martin Nachbar, M.D.
Assoc. Prof. of Medicine and Microbiology
Director, Academic Computing
New York University Medical Center
550 First Avenue
New York, NY 10016
(212) 263-5744
Fax (212) 263-8542
nachbar@@popmail.med.nyu.edu
Copyright 1997 New York University
All Rights Reserved