1. Dalhousie University Senior Design Project
Magnetic and articulating (MNA) Bougie assisted breathing tube placement during intubation
Group Members:
Chris Cloney
Laura Hadley
brian joseph
Ian Westhaver
Supervisor: Dr. Ted Hubbard
Clients: dr. Andrew Milne1,2, dr. Dennis Drapeau1
1 Department of anesthesia – Dalhousie university
2 School of Biomedical Engineering – Dalhousie University
Group #7
Dalhousie University Senior Design Project

2. Overview Introduction Requirements Methodology
Testing and Initial Design
Final Design
Results
Future Plans
Adapted from Fong 2004 [1]

3. Introduction to Standard Intubation
Current Devices
Breathing tube
Laryngoscope
Technique
Achieve visualization
Insert breathing tube
15-17,000 intubations per year (QEII – anesthesia department )

4. Design Problem
Difficult Intubation: 2-3% of all intubations (300 – 500 per year)
Design and construct a device to use with a video laryngoscope to insert a breathing tube in difficult intubation scenarios.
Introducing
Bougie

5. Design Requirements Requirement Result Medical grade materials
Disposable or easily sterilized
Portable, volume less than 3500 cm3
Light, weigh less than 3 kg
1-2 attempts to introduce breathing tube
Less than 25 seconds

6. Design Methodology Mechanical devices Magnets Difficult to use
Intuitive
Allows for fine motion

7. Testing – Distance X Minimum distance required for attraction
Error bars at 95% confidence (3 trials)
Minimum attraction distance between small magnet and large ceramic magnet. It was determined that a magnet with the strength of at least 6 ceramic magnets should be used.

8. Testing – Forces X Minimum separation force
Error bars at 95% confidence (5 trials)
Force required to pull magnets off of a steel beam. This standard test case is used to size commercial magnets for purchase.

9. Key Features Bougie External magnet
Magnetic tip attracted into trachea
Flexible tip to encourage articulation
In conjunction with video laryngoscope
External magnet
Attracts magnetic bougie tip
Varying force
Controlled by anesthesiologist or anesthesiologist's assistant

10. Initial Design Bougie External magnet Tip not rigid enough
Tip connection is too delicate
MAGNET
External magnet
Cumbersome
Imprecise control
The initial bougie design featured a magnet tip on a cord with an inflatable chamber. The magnet tip would be attracted to the external magnet and guided into the trachea, and the chamber would be inflated. This inflation would effectively lengthen the bougie. The breathing tube is then guided into the trachea using the bougie and the bougie is removed. We found that the tip was too flexible, and the likelihood of the magnet becoming detached was too high. From this, a tip that is softer but not completely flexible is needed.
The initial external magnet design featured a magnet attached to a cam follower to be placed on the patient’s neck. The magnet would attract the internal magnet into the trachea. The force of the external magnet applied to the internal magnet is adjusted by the cam mechanism. We found that this device hindered the intubation procedure, and so a smaller device is needed.
MAGNET

11. Final Design Two Components External magnet moves flexible bougie tip
Interior bougie
External magnet moves flexible bougie tip
From this our final design features a handheld external magnet, and a bougie with a magnetic and flexible tip, and a balloon.

12. Final Design – Bougie
Magnetic Tip
Balloon
Connection

13. Final Design – Bougie Balloon Inflated by syringe Coarse articulation
50 mm

14. Final Design – Bougie Connection
Joins flexible end to stiffer bougie shaft
Flexible material allows for greater tip articulation

15. Final Design – Bougie Tip Magnet encased by flexible tip
Fine articulation

16. Final Design – Magnet

17. Final Design – Magnet
Shell
Can be disassembled for cleaning

18. Final Design – Magnet
Magnet
1-1/2” dia. x 1/4” thick
50 N

19. Final Design Implementation
Magnetic Tip (Yellow)
Flexible Tip (White)
Balloon (Orange)
Trachea (Green)
Esophagus (Red)
Lung (Pink)

20. Safety Sterilization No detachable parts Forces Disposable bougie
Casing easily disassembled
No detachable parts
Forces
Cricoid pressure
(30–40 N) [3]
Less than 10 N
Error bars at 95% confidence (3 trials)

21. Results Requirement Result Medical grade materials Plastics
Disposable or easily sterilized
Both
Portable, volume less than 3500 cm3
< 500 cm3
Light, weigh less than 3 kg
< 0.5 kg
1-2 attempts to introduce breathing tube
TBD
Less than 25 seconds

22. Future Plans
Construction of first iteration of final design by Jan 31st
Testing completed through month of February
Usability of external design
Forces directly on vocal cords
Possible cadaver testing
Iteration of design and final construction

23. Questions? Acknowledgments References
We would like to thank our clients Dr. Andrew Milne and Dr. Dennis Drapeau for their time and insight on this project.
We would also like to thank our supervisor Ted Hubbard for the direction and intuition provided for this project.
References
[1] Sally Fong Intubation. Retrieved from
[2] Rassam, S., Wilkes, A., Hall, J., Mecklenburgh A comparison of 20 laryngoscope blades using intubating manikin: visual analogue scores and forces exerted during laryngoscopy. Anaesthesia 60:
[3] Vanner, R Tolerance of cricoide presure by conscious volunteers. International Journal of Obstetric Anesthesia. 1:4:

24. Medium Testing