MAGNETIC AND ARTICULATING (MNA) BOUGIEASSISTED BREATHING TUBE PLACEMENT DURING INTUBATION

Dalhousie University Senior Design ProjectGroup #7

GROUP MEMBERS: CHRIS CLONEYLAURA HADLEYBRIAN JOSEPHIAN WESTHAVER

SUPERVISOR: DR. TED HUBBARD

CLIENTS: DR. ANDREW MILNE1,2, DR. DENNIS DRAPEAU11 DEPARTMENT OF ANESTHESIA – DALHOUSIE UNIVERSITY2 SCHOOL OF BIOMEDICAL ENGINEERING – DALHOUSIE UNIVERSITY

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Overview Introduction Requirements Methodology Testing and Initial

Design Final Design Results Future PlansAdapted from Fong 2004 [1]

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Introduction to Standard Intubation

Current Devices Breathing tube Laryngoscope

Technique Achieve visualization Insert breathing tube

15-17,000 intubations per year (QEII – anesthesia department )

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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.

IntroducingBougie

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Design Requirements

Requirement ResultMedical 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

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Design Methodology Mechanical devices

Difficult to use Magnets

Intuitive Allows for fine motion

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Testing – Distance

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.

0 1 2 3 4 5 6 7 8 90

10

20

30

40

50

60

70

80

Magnet Only Magnet on Bougie (125 mm)Magnet on Bougie (100 mm)

Number of Ceramic Magnets

Dis

tanc

e (m

m)

X

Error bars at 95% confidence (3 trials)

Minimum distance required for attraction

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Force required to pull magnets off of a steel beam. This standard test case is used to size commercial magnets for purchase.

Testing – Forces

0 1 2 3 4 5 6 7 80

10

20

30

40

50

60

Number of Ceramic Magnets

Forc

e (N

)

X

Error bars at 95% confidence (5 trials)

Minimum separation force

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External magnet Attracts magnetic bougie tip Varying force Controlled by anesthesiologist

or anesthesiologist's assistant

Bougie Magnetic tip attracted into trachea Flexible tip to encourage articulation In conjunction with video

laryngoscope

Key Features

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External magnet Cumbersome Imprecise

control

Initial Design Bougie

Tip not rigid enough

Tip connection is too delicate

MAGNET

MAGNET

Final Design Two Components

External magnet Interior bougie

External magnet moves flexible bougie tip

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Final Design – Bougie

Balloon Connection

Magnetic Tip

Final Design – Bougie12

Balloon• Inflated by syringe• Coarse articulation

50 mm

Final Design – Bougie12

Connection• Joins flexible end to

stiffer bougie shaft• Flexible material

allows for greater tip articulation

Final Design – Bougie12

Tip• Magnet encased by

flexible tip• Fine articulation

Final Design – Magnet13

Shell• Can be

disassembled for cleaning

Final Design – Magnet13

Magnet• 1-1/2” dia. x 1/4” thick• 50 N

Final Design – Magnet13

Final Design Implementation

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Magnetic Tip (Yellow)

Flexible Tip (White) Balloon (Orange) Trachea (Green) Esophagus (Red) Lung (Pink)

Safety

Sterilization Disposable bougie Casing easily

disassembled No detachable parts Forces

Cricoid pressure (30–40 N) [3]

Less than 10 N

15

0 5 10 15 20 25 30 35 40 450.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

6 Ceramic Magnets

Distance between large and small magnets (mm)

Forc

e (N

)Error bars at 95% confidence (3 trials)

Results16

Requirement ResultMedical grade materials PlasticsDisposable or easily sterilized BothPortable, volume less than 3500 cm3 < 500 cm3

Light, weigh less than 3 kg < 0.5 kg1-2 attempts to introduce breathing tube TBDLess than 25 seconds TBD

Future Plans17

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

Questions?18

AcknowledgmentsWe 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. 2004. Intubation. Retrieved from http://www.aic.cuhk.edu.hk/web8/Intubation.htm[2] Rassam, S., Wilkes, A., Hall, J., Mecklenburgh. 2005. A comparison of 20 laryngoscope blades using intubating manikin: visual analogue scores and forces exerted during laryngoscopy. Anaesthesia 60:384-394[3] Vanner, R. 1992. Tolerance of cricoide presure by conscious volunteers. International Journal of Obstetric Anesthesia. 1:4:195-198

Medium Testing