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

Overview Problem Statement Motivation Background Information Client Requirements Design Alternatives Future Work

Problem Statement Build mechanical respiratory model for class instruction Display alveolar and intrapleural pressures Demonstrate rib cage and diaphragm expansion Properly scale lungs Portable Usable with document camera Operable by single user

Problem Motivation Current device breaks easily  Must replace whole unit Poor physiological accuracy No pressure comparison

Background Thoracic Cavity = Ribs + Heart + Trachea + Lungs + Diaphragm Breathing causes pressure changes in lungs Alveolar pressure, P alv Intrapleural pressure, P pl

Background Continued Lung Volume dependent on:  Difference between P alv & P pl  Lung elasticity Intercostal muscles and diaphragm modulate lung expansion 4

Client Requirements Display pressure differences Demonstrate diaphragm and rib cage motions Usable with document camera Easily replaceable parts Integrate w/computer BIOPAC (2 nd semester)

Current Devices Dome Plexiglas ® container Balloons to represent lungs Single elastic membrane for diaphragm 20demos/Lung%20Model.htm

Homemade model Current device models Animated online models No physical models that represent the thoracic movement Competition

Design Constraints Must be operable by one person Must weigh less than 20 lbs Need parts that can be replaced easily Fits on document camera (~11x14in) Budget: Under $500

General Design. Clear acrylic thoracic cavity Flat back for document camera Custom elastic lungs Healthy Emphysema Pressure gauges show relative pressures Alveolar Intrapleural

Hinged Door Design Common features Hinged doors show rib expansion Elastic diaphragm membrane Hinged Doors Show Rib Expansion Alveolar and Intrapleural Pressure Gauges Elastic Diaphragm Membrane Custom Elastic Lungs Clear Acrylic Thoracic Cavity Flat Back for Use on Document Cam

Pros Elastic membrane similar to diaphragm muscle Diaphragm membrane easily replaceable Doors represent partial movement of ribcage Cons Doors hard to seal with membrane Membrane wears quickly Low change in volumes Three handle operation Hinged Door Design

Common features Membrane constrained panel shows rib expansion Large diameter piston for diaphragm Membrane Constrained Panel Shows Rib Expansion Large Diameter Piston for Diaphragm Rib Membrane Design

Pros Diaphragm piston provides large volume displacement Two handle operation Rib membrane easily replaceable Cons Membrane wears quickly Rib operation may obscure lungs Hard to get large volume with “ribs” Rib Membrane Design

Common features Membrane constrained quarter sections show rib expansion Elastic diaphragm membrane Membrane Constrained Quarter Sections Show Rib Expansion Elastic Diaphragm Membrane Quarter Section Design

Pros Quarter sections physiologically representative Diaphragm membrane easily replaceable Cons Sections hard to seal with membrane Membrane wears quickly Three handle operation Quarter sections only attached by membrane Quarter Section Design

Design Matrix Design 1: Hinged Door Design 2: Rib Membrane Design 3: Quarter Section Ease of Replacement (20) Physiological Accuracy (20) Ease of Use (15)10155 Durability (15)10155 Pressure Display (10)999 Weight (10)888 Cost (10)888 TOTAL (100)708570

Future Work Order materials Construct prototype Test device Revise design as needed More material & electronics research Computer/software integration

References 1.Model of the Lungs and Diaphragm. ng%20Model.htm (16 October 2007) 2.Brown, A Physiology of the Respiratory System. (14 October 2007) 3.United Spinal Association (14 October 2007) 4.Widmaier, E. et al Human Physiology: The Mechanisms of Body Function. Boston, McGraw-Hill, pp

Questions