1. The No-Hurt Insert:
Proximity Device to
Monitor ETT Position
Hyde, Manuel, Russin, Shrestha
Senior Projects Conference
May 9, 2014
2. Complications of Endotracheal Intubation
Esophageal Intubation
Patient hypoxia
Bronchial Intubation
Right lung hyperinflation
Left lung collapse
These problems are caused by
prolonged endotracheal tube
(ETT) misplacement
Divatia, J.V., and K. Bhowmick. "Complications of Endotracheal Intubation and Other Airway Management Procedures.“ Indian Journal of
Anaesthesiology 49.4 (2005): 308-18.
Adapted from Wikipedia user PhilippN
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carina
3. Problems with Current Solutions
• Chest X-Ray
– Verifies ETT placement inside
trachea (Hossein-Nejad 2013)
– Radiation exposure on the order
of 3-4 mRem (Bubsy 2011)
• Bilateral Ausculation
– Listening to breaths using a
stethoscope
– 60% of main stem bronchial
intubations occurred despite the
presence of equal breath sounds
(Brunel et al. 1989)
Bubsy, Bruce. "Radiation and Risk." The Radiation Information Network.
Idaho State University. 2011.
Brunel, W., D.L. Coleman, D.E. Schwartz, E. Peper, and N.H. Cohen.
"Assessment of Routine Chest Roentgenograms and the Physical Examination
to Confirm Endotracheal Tube Position." Chest 96.5 (1989): 1043-1045.
Adapted from Khan 2009
Adapted from gstatic.com
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4. Problems with Current Solutions
Capnometry
Monitoring of concentration and
partial pressure of CO2 in exhaled air
Cannot detect endobronchial
intubation
An ideal solution would involve continuous
monitoring of the position of the ETT so that it
would always be where it needs to be
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Sanders, A.B.. "Capnometry in Emergency Medicine." Annals of Emergency Medicine 18.12 (1989): 1287-90.
5. Specifications
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Product Specification Design Specification
1. Product cannot fall off in patient Degree of Collapse < 0.5 under ISO
standard 10079-3
2. Airflow change caused by the
product must be insignificant
Airflow cannot be reduced by more than
20% under ASTM F 1242-96 and ISO 5631
3. End user is alerted with well-
understood alarms
Alerts with tonal sequence of A4-C4-F4-
A4-C4 under IEC 60601
4. Immune to the operational
environment
Variations in humidity and temperature
do not affect the results
5. Negligible time to first results Time for data acquisition is less than half
a second
6. Electrical components must be
isolated from the patient
No exposed wires and leakage current
will meet IEC 60601 (under 300 µA)
7. Materials are biocompatible Product composed of same material as
endotracheal tube
6. Standards-Driven Specifications
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PS 1: FIXATION
Same Material as ETT
Diameter
deformation of <50%
ISO 10079-3
ASTM F 1242-96 F, ISO 5361
ISO 10993
IEC 60601
Does not significantly
affect airflow
PS 7:
BIOCOMPATIBILITY
PS 2: AIRFLOW
PS 3: ALERT
MECHANISM
Alerts User with a
sequence of tones
(C,A,F,A,F) / (C,A,F)
7. Work Plan
Identify the primary problem
Analyze potential solutions
Construct prototype
Test prototype
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9. Design Option 1: One-Camera System
General Process:
Use focal point to measure
distance to a known object
Output data outlining
quantitative depiction of
distance
Why Not:
Percent error too large for
accurate results (~15000%)
Camera requires light
Screenshot from the app “EasyMeasure”
yielding nearly 15000 % error
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10. Design Option 2: Two-Camera System
General Process:
Take 2 video streams & overlay
them; run Fourier transforms
Output a third, interpreted video
stream outlining quantitative
depiction of distance
Why Not:
Processing time
Fitting two cameras into a trachea
would be problematic size-wise
Cameras require light
Not feasible in given time frame
Overlaid interpreted image of the
two raw images (above).
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11. Design Option 3: Proximity Sensor
General Process:
Ultrasonic wave +
acoustic theory to
determine distance
between sensor and object
Sensor outputs data
outlining quantitative
depiction of distance which
alerts changes in position
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Figure adapted from Dr. Hall’s
PING))) presentation
𝑣 𝑠𝑜𝑢𝑛𝑑 =
1 𝑖𝑛
74 µ𝑠
𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 =
𝑣 𝑠𝑜𝑢𝑛𝑑 ∙ 𝑡
2
13. Verification of physical proportionality between our
plastic model and the average human trachea
Feasibility Model Dimensions
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14. Calibration of PING))) Sensor
y = 0.9972x + 0.1231
R² = 0.9998
0
10
20
30
40
50
60
70
0 10 20 30 40 50 60 70
PING)))Distance(cm)
Actual Distance (cm)
Data becomes erroneous at distances <2 cm
http://www.rlx.sk/product.php?id_product=877
Calibration station
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15. Feasibility Experiment
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Goal: Determine functionality of ultrasonic sensor for detecting carina
18. Calibration of LV-EZ3 Sensor
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y = 3.8447x + 2E-13
R² = 1
0
50
100
150
200
250
300
350
400
0 10 20 30 40 50 60 70 80 90 100
MeasuredVoltage(mV)
Sensor-Calculated Distance (cm)
Linear region of sensor: 3.8447 mV / cm
This value was used in coding to calculate distance
amazon.com
19mm x 22mm
19. Works-Like Prototype v. 1.0
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5 cm x 5
cm grid 1 tick mark = 1 cm
1st Attempt at 10x scaled-up
model for testing
20. Represents active
sensing area for
our sensor
Provides a model
of how our sensor
will function; we
used this to
construct the
model trachea in
which we tested
our device
Sonic Cone Profile
-30
-20
-10
0
10
20
30
0 20 40 60 80 100
LateralDistancetoReferenceAxis
(cm)
Object Distance from Sensor (cm)
Experimental Sonic Cone Profile
(Adapted from MaxBotix Datasheet)
Problem Solutions Specifications Design Prototype Testing Review Future
21. Works-Like Prototype v. 2.0
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5 cm x 5 cm grid
carina
6 cm
Stabilizer
Stabilizer
22. Works-Like Prototype Validation
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Our prototype detects distance between the sensor and carina.
23. User Interface for Sensor Output
Too far Too close
Appropriate
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28. Looks-Like SolidWorks Model
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Top View
Front View Isometric Right View Section View
3.8 cm
Ø = 13.4 mm
12.2 mm
29. Looks - Like Prototype
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DTA
Monitoring
System
Endotracheal Tube
30. Airflow Model (Specification 2)
Poiseuille’s Law for Fluid through a Tube:
∆𝑃 =
8𝜇𝐿𝑄
𝜋𝑟4 = 4.41 Pa
ΔP: pressure drop
L: tube length (30 cm)
µ: dynamic viscosity of air (0.02 cP)
Q: volumetric flow rate of air (≥ 7.2 L/min)
r: tube radius (4.5 mm)
http://www.kirbyresearch.com/
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31. COMSOL Airflow Model (Spec. 2)
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DTA
cm
cm
cm
cm
ETT
COMSOL Simulation: Airflow at 370 L/min
32. Statistical Analysis of Flow Rate
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00:10
Upper
Reservoir
Timer
ETT
Graduated
Cylinder
Tubing
Two-tailed t-test, equal variance
P < 0.05 indicates statistical difference
The null hypothesis was not rejected
Null Hypothesis: DTA does not
affect flow rate (Specification 2)
33. Fixation Strategy Testing
IDinitial
(mm)
ODinitial
(mm)
ODtest
(mm)
Degree of
Collapse Pass/Fail
Trial 1 8.81 11.74 11.30 0.05 PASS
Trial 2 9.09 11.71 11.05 0.07 PASS
Trial 3 8.89 11.70 11.46 0.03 PASS
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Testing Design Specification 1: Degree of collapse must be <0.5
60 kPa vacuum for 5 minutes at a time
34. Review
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Design Specification Did we meet the specification?
1. Degree of Collapse < 0.5 under ISO
standard 10079-3
Yes
2. Airflow cannot be reduced by more
than 20% under ASTM F 1242-96 and
ISO 5631
Yes
3. Alerts with tonal sequence of A4-C4-
F4-A4-C4 under IEC 60601
Yes
4. Variations in humidity and
temperature do not affect the results
N/A
5. Time for data acquisition is less than
half a second
Yes
6. No exposed wires and leakage current
will meet IEC 60601 (under 300 µA)
N/A
7. Product composed of same material as
endotracheal tube
N/A
35. Future Work
New Specs:
Material of sensor
Better field depth
Biocompatibility
Stability of the collimation in the final system
Most Promising Aspect:
Direct measurement of the distance rather than
interpolation
Hindrances to implementation:
Precision of tools and machines
Revision steps for the creation of a new sensor
Problem Solutions Specifications Design Prototype Testing Review Future
36. Future Work
J. Yang, R. Chen, et al., "A 2.5-mm diameter probe for photoacoustic and ultrasonic endoscopy," Opt. Express 20, 23944-23953 (2012).
Make the current system
wireless
Create size-appropriate
sensor through the IFM
Cone Profile can be
collimated – the focus of
the field can be adjusted
Make the scaled down
system wireless
Problem Solutions Specifications Design Prototype Testing Review Future
Df = 7.1 F2λ
37. Not Pictured: Vinh Lam, Gordon Reger, Vassia Roulia
Acknowledgements
LSUHSC-Shreveport
Dept. of Anesthesiology
Louisiana Tech University
Dr. Charles Fox III Dr. J. Arthur Saus
Dr. Sridhar Tirumala Dr. Sudipta Sen Dr. Craig Hamilton
Dr. Patrick O’Neal
Dr. Kelly Crittenden
Austin Hoggatt
Dr. Abdul Khaliq Jeffery Weisman
// Design Constraints and Specs one slide if possible with two columns
// Design Constraints and Specs one slide if possible with two columns
// flowchart
//Color coded with work distributed among team members
SAY THIS: Even if we were to outsource the creation of an app with minimal error, the camera would likely be too large to fit in the distal end of the ETT. Additionally, the camera and the processor would need to be in the end of the tube or there would need to be long, soldered wires connecting the camera to the processor located outside the body.
SAY THIS: There are large processing delay elements inherent to the dual camera system. Retrieval of 640x480 images takes 32 milliseconds (60 frames per second), and MATLAB processing of 640x480 images takes 3.3s per data set. This means that in the time it takes to process the first data, there would already be 198 more sets to process. These will accumulate exponentially, causing additive delay.
//Need labels and scale on pictures
// Need text saying 10x model
David
// Need a text saying scale for each grid at the bottom
Ranjita
Hannah
// New video
David
Hannah
// picture of ETT + DTA with everything labeled like Murphy eye, DTA, etc
// Make picture easily understandable
// Labels and scales???
// Labels and scales: not sure if the scales are correct
// Need text on statistical testing for what? // Describe specific specification for what we are testing
// one-tailed? // P-vales > 0.05 is not significant
