Inventive Problem Solving
Ideation Process
Project Initiation
Project Name: UV Light Wand for Elimination of Bacteria Found in Pediatric Endotracheal
Tubes
Project Timeline:
Project Team and Contact Information:
Sarah Hodges
[email protected]
(404) 314-0729
Matthew Sundermann
[email protected]
(412) 417-2861
Jeffrey Turner
[email protected]
(201) 919-0975
Sarah Williams
[email protected]
(770) 296-8118
Advisor Contact Information:
Ty Berutti, MD, MS, MS
Assistant Professor, Pediatric Critical Care
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Monroe Carell Jr. Children's Hospital at Vanderbilt
[email protected]
Neal Maynord
Pediatric Critical Care Fellow
Monroe Carell Jr. Children's Hospital at Vanderbilt
[email protected]
Paul H. King
Vanderbilt University School of Engineering, Department of Biomedical Engineering
[email protected]
1. Project objectives
· Design a device using UV technology which kills resident bacteria present in pediatric
endotracheal tubes in order to reduce the risk of ventilator associated pneumonia
· The device should deliver UV light to the entire endotracheal tube without escaping from
the tube
2. Importance of the Situation
A common problem in pediatric intensive care units (PICU) is the occurrence of ventilatorassociated pneumonia (VAP) caused by extended use of mechanical ventilation. The disease
leads to extended hospital stays, increased cost, and increased mortality rates. One of the most
significant risk factors associated with VAP is the presence of a foreign body or in this case an
endotracheal tube in the body for an extended amount of time. This project seeks to decrease
the build- up of bacteria within the tubes that often result in episodes of VAP.
Innovation Situation Questionnaire
1. Brief description of the situation
The situation involves finding a solution that helps reduce the bacteria that builds up within an
endotracheal tube during ventilation..
2. Detailed description of the situation
2.1. Supersystem - System - Subsystems
2.1.1. System name
UV light wand to kill bacteria within pediatric endotracheal tubes
2.1.2. System structure
The system includes a UV light source (UV LED or UV laser) and hollow waveguides that are
connected to shine UV light within an endotracheal tube.
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2.1.3. Supersystems and environment
The enivronment surrounding the light wand is assumed to be between body temperature and
room temperature. The system must be able be placed within moist or wet conditions.
2.1.4. Systems with similar problems
Systems with similar problems include adult patients with endotracheal tubes for ventilation.
The size of the pediatric tubes prevents all of the same solutions to be used for both adult and
pediatric patients.
2.2. Input - Process - Output
2.2.1. Functioning of the system
The wand needs to be able to emit UV light out of its sides and not out of the end to be able to
kill bacteria along the sides of the tube and not escape out the hole at the end of the
endotracheal tube.
2.2.2. System inputs
Inputs to the wand include the power and wavelength of the light emitted from the light
source into the optical fibers.
2.2.3. System outputs
System outputs include radiation and heat.
2.3. Cause - Problem - Effect
2.3.1. Problem to be resolved
The problem that we would like to resolve is bacteria that builds up in the endotracheal tube
and can lead to Ventilator Associated Pneumonia.
2.3.2. Mechanism causing the problem
Proposed modes of infection include inhalation of aerosols containing bacteria, oral secretions,
and spread of bacteria from the gastrointestinal tract. Infections most commonly include
Pseudomonas aeruginosa, Enterobacteriaceae, and Staphylococcus aureus from the VAP
aspirates.
2.3.3. Undesirable consequences if the problem is not resolved
Undesirable consequences of the problem include Ventilator Associated Pneumonia, increase
hospital stay, increase hospital cost, and increased risk of death.
2.3.4. Other problems to be solved
Other problems to solve would include preventing build up of bacteria along the endotracheal
tube which would eliminate the need to kill bacteria within the tube.
2.4. Past - Present - Future
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2.4.1. History of the problem
Currently, endotracheal tubes are cleaned using a vacuum system called a ballard that removes
bacteria and mucus build up within the tubes. There are also silver coated tubes that help
reduce bacteria formation in the tubes.
2.4.2. Pre-process time
If silver coated tubes and the ballard are used at the beginning of ventilation, the bacteria
within the tube will be reduced and the use of the UV wand will be more effective at killing
bacteria and preventing Ventilator Associated Pneumonia.
2.4.3. Post-process time
The ballard can be used after the UV light wand is used to clean out the debris.
3. Resources, constraints and limitations
3.1. Available resources
SUBSTANCE RESOURCES:
endotracheal tube
bacteria
UV radiation
FIELD RESOURCES
UV radiation
SPACE RESOURCES
wand has to fit within the smallest pediatric endotracheal tube (3 mm diameter)
length of endotracheal tube
HUMAN RESOURCES
our design team- Sarah Hodges, Matt Sundermann, Jeff Turner, Sarah Williams
our advisors- Ty Berutti, Neal Maynord, Paul King
3.2. Allowable changes to the system
Small changes in the type of endotracheal tubes may be allowed. This may help the UV light
wand be more effective but will be more expensive because silver coated tubes are a little bit
more expensive that the endotracheal tubes that are most frequently used.
We can also change the source of light within the wand. UV lasers will provide more
powerful light than UV LEDs. The collumnated light from the laser will be more easy to
couple into the tube. It may also reduce light that is lost so that a higher intensity of light
reaches the end of the tube.
3.3. Constraints and limitations
The total diameter of the wand cannot be changed because it has to fit down the smallest
pediatric endotracheal tube (3 mm diameter). The length of the light wand has to be able to
reach the end of the largest endotracheal tube. The hollow waveguide has to be flexible
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Inventive Problem Solving
enough to make the sharp bend that the tube makes within the trachea.
3.4. Criteria for selecting solution concepts
Criteria for selecting a solution include the elimination of bacteria from within an endotracheal
tube without allowing UV light to escape the wand into surrounding tissue.
Problem Formulation and Brainstorming
Diagram--UV Light Wand for Endotracheal Tube
3/30/2011 10:34:53 PM.
1. Find an alternative way to obtain Kill bacteria that offers the following: does not
require Illuminate side of endotracheal tube with UV light is not influenced by Flexible to
make bend in trachea.
3. Resolve the contradiction: Fit within a pediatric endotracheal tube should be provided
to produce Illuminate side of endotracheal tube with UV light and shouldn't be provided
to avoid Obstruct endotracheal tube.
6. Resolve the contradiction: Illuminate side of endotracheal tube with UV light should be
provided to produce Kill bacteria and shouldn't be provided to avoid Irradiate tissue.
7. Find a way to eliminate, reduce, or prevent Irradiate tissue under the conditions of
Illuminate side of endotracheal tube with UV light.
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Develop Concepts
1. Categorize preliminary ideas
Light Source
water sterilization system
UV LED
UV Laser
Fiber Technology
traditional fiber optics
hollow waveguides
mirror system
Reflective Tip
mirrors
scattering device
2. Combine ideas into concepts
A UV LED of UV laser can be used as the light source to transmit UV light down hollow
waveguides. The light will then be scattered at the end to be reflected on the sides of the tube
to kill bacteria.
Evaluate Results
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1. Meet criteria for evaluating Concepts
Improve convenience
Make the device easily sterilizable. Disposable protective sheaths can be used to easily
reuse the device. Also, the device should have an easily portable light source.
Increase reliability
Add protection around the fiber to prevent breaking. Stong epoxy needs to be used to securely
attach the fiber to the light source so that no light is lost in movement.
Reduce cost
Make the device reusable and easily sterilizable. The type of laser will determine the total
cost of the product.
Reduce energy consumption
Use the lowest power that will effectivly kill bacteria but also fit within the time constraints
that the tube is allowed to be obstructed.
Improve functional efficiency
To make the product more effective however, a higher power of light source will need to be
used. A high powered laser will be the most effective source because the most light from the
source will be able to be coupled into the fiber with large amounts of light loss.
Reduce interaction with the environment
Make sure the device is fully sealed and that a vacuumed area will contain nitrogen so that the
atmosphere does not absorb most of the UV light.
2. Reveal and prevent potential failures
Potential failures
- the fiber is unable to bend enough to fit down the smallest ETT
- a laser source is not even powerful enough to kill enough bacteria
- too much light is lost in scattering the light that does travel down the hollow waveguide
- too much light is lost in coupling of the device
3. Apply Patterns/Lines of Evolution
Increasing ideality
The ideality can be increased by increasing the power so that more bacteria is killed. The
preciseness of coupling will also ensure less power to be lost so the most bacteria can also be
killed. To reduce undesired features such as exposure of the tracheal tissue to UV light, silver
coated ETT tubes should be used.
Element universalization
Elements that can easily adjust the amount of power of the light that is used would be a good
feature adjust the light depending on the size of tube that is used to get more consistent results
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Inventive Problem Solving
in all sizes of tubes.
4. Plan the implementation
To implement the project, sample hollow waveguides will be obtained to couple light from a
UV LED and a blue laser light source. This will help prove whether the concept of a device
using UV light would be an effective way to kill bacteria in endotracheal tubes.
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