1. Endotracheal Tube Pressure Monitor
Client: Dr. Lester Proctor Professor of Anesthesiology
Advisor: Dr. Paul Thompson
Andrew Bremer
Colleen Farrell
Val Maharaj
Deborah Yagow

2. Overview Problem Statement Background Information Client Requirements
Design Alternatives
Design Matrix
Final Design and Future Work
References

3. Problem Statement
Dr. Lester Proctor has expressed the need for a pressure indicator which would be used for endotracheal tubes. Over inflation of the cuff on an ET tube can cause tracheal damage, especially in children, and Dr. Proctor is looking for a qualitative indicator which would be attached to the ET tube and would give a consistent reading on the pressure in the inflated cuff.

4. Background Information
Intubation Practice on STAN
Intubated Patient [Source:

5. Client Requirements Cheap and disposable Size Consistent measurement
Permanently attached to ET tube
Versatile enough to use on any size ET tube
Meets FDA safety requirements

6. Alternative Design 1: Mechanical Spring
Continuing prototype
Air pressure compresses spring
Indicating stem
Colors represent pressure ranges
T-Valve
Mechanical Spring Design (Endotracheal 17)

7. Alternative Design 2: Revised Mechanical Spring
Clear cylinder
Internal indicator
Air escape
Revised Mechanical Spring Design

8. Alternative Design 3: Enclosed Balloon
Balloon inside cylinder
Attaches over lead tube
Acts as indicator
Inflates according to cuff pressure

9. Alternative Design 4: Electric Pressure Transducer
Silicone diaphragm containing strain gauges
Wheatstone Bridge
Comparators
LED lights or LCD digital display readout
Omega PX DV
Low Cost Silicon Pressure Sensor with Millivolt Output

10. Alternative Design 5: Color Changing Plastic
New technology
Used as balloon or diaphragm
Plastic film changes color as stretched
Different colors represent pressure ranges
Plastic Film
(Source: Interactive Imaging Solutions)

11. Color Changing Plastic
Design Matrix
Category
Weight of Category
Electronic
Mechanical Spring
Balloon
Revised Spring
Color Changing Plastic
Safety 5 3 4
Ease of Use 15 11 13 14
Client Preference 10 8 6
Effectiveness
Price 20 16
Size 17
Durability/ Repeatability 7 1
Ease of Manufacturing
Total
100 54 80 81 85 65

12. Final Design Revised mechanical spring design Rolling diaphragm
(HydraulicsPneumatics)

13. Future Work Material Research Build prototype Testing
Calculation of spring constants
Calibration of indicating segments
Build prototype
Testing

14. References
Endotracheal Tube Cuff Pressure Indicator. December University of Wisconsin- Madison Biomedical Engineering Department. 28 February < Cuff_Pressure_Indicator.pdf>
Hi-Lo® Tracheal Tube with Lanz® Pressure Regulating Valve Nellcor Puritan Bennett LLC. 28 February <
Hydraulics and Pneumatics Penton Media Inc. 29 Feb <
Introduction to Pressure Transducers Omega Engineering. 28 Feb <
Proctor L Professor. Departments of Anesthesiology and Pediatrics, University of Wisconsin Medical School, Madison, WI Pers. Comm..
SolidWorks Software Education Edition. Copyright SolidWorks Corporation.
Spray SB, Zuidema GD, Cameron JL. Aspiration pneumonia; incidence of aspiration with endotracheal tubes. Am J Surg. 1976;131:701–703.
Surface Inspection System for Plastic Film & Sheet. Interactive Imaging Solutions. 5 March < linescan.com/pageseditos,20,left_E230F666,plastic,film,sheet,surface,inspection.html>
Webster, J.G. (ed.) Bioinstrumentation. New York: John Wiley & Sons.