Human Respiratory Mechanics Demonstration Model Team Members: Kristen Seashore, Co-leader Lynn Murray, Co-leader Janelle Anderson, Communicator Malini Soundarrajan, BSAC Chris Goplen, BWIG Clients: Andrew Lokuta, Ph.D Kevin Strang, Ph.D Advisor: Naomi Chesler, Ph.D

Overview Background Client Requirements Previous Work New Design BioPac Integration Testing IRB Approval

Background Pressure changes in thoracic cavity  changes in lung volume  breathing P alv = Alveolar Pressure P pl = Intrapleural Pressure Movement of ribs & diaphragm cause pressure changes

Client Requirements Portable respiratory model Display alveolar & intrapleural pressures Show rib cage and diaphragm effects Easily replaceable parts Integrate with BioPac ® software Budget: $500

Previous Work Built “rib membrane” model –Analog pressure gauges –Gauges not sensitive enough –Construction problems –Previous design obscured lungs Lung material testing Initial pressure testing Membrane Constrained Panel Shows Rib Expansion Large Diameter Piston for Diaphragm

New Design Reposition rib membrane –Flat flange allows better sealing Incorporation of electronic gauges and displays Residual negative intrapleural pressure Seamless, leak-proof lungs New material: Polycarbonate –‘Machinablility’ vs. scratch resistance

New Design Rib membrane moved to sides Utilizes same piston Plug allows residual negative pressure Seamless lungs Old DesignNew Design Doc-cam flat back maintained *Electronic gauges/displays not shown on New Design

Software BioPac used by clients Electronic pressure sensors Adapted sensors for MP30

Future Testing - Leak-proof test new prototype - Signal calibration and smoothing - BioPac testing - Effectiveness in the classroom - Pressure testing

Expected Pressures By piston mechanism: –About 7 kPa (according to calculations) By rib membranes: –Half of piston pressure –About 3.5 kPa

IRB Approval Goal: determine the efficacy of model Plan: –Survey Physiology 335 students –Test before and after viewing model –Assess knowledge gained and utility of model

Study Design

Data Analysis & Expected Results Three different analyses: –Compare individual pre- and post-test scores Two sample t-test Expect 1-2 point increase (out of 7) –Compare average pre- and post-test scores Expect a higher average score in post-tests –Compare groups from different days Use data to eliminate confounding variables

Questions?