Infection Prevention Urinary Catheter

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Sponsors
Team Name Infection Protection
Duration Fall 2018 - Spring 2019
Faculty Adviser
  • Dr. Michael Maughan
Mentor
  • Andre Corpus
Client
  • Name / Organization
Team Members
  • Ed Hall
  • Amy Macias
  • Elena Tipton

The goal of the project is to design and develop a urinary catheter that can reliably reduce the incidence of Catheter-Associated Urinary Tract Infections (CAUTIs).


Problem Definition[edit]

Background[edit]

Catheter-Associated Urinary Tract Infections (CAUTI)

Indwelling urinary catheters are commonly used in both hospitals and nursing homes to help relieve patients with urinary incontinence or urinary retention. The use of a catheter allows the patient to empty their bladder. In most occurrences, catheters are used until the person can regain control of the bodily function, however, in many instances with elderly people or with individuals who have a permanent injury of illness, catheters are used on a long-term or permanent basis. While it is a very important device used in the healthcare industry, there is a large problem associated with the use of the traditional Foley catheter. Long-term catheter usage (2 weeks or more) is closely associated with high rates of Catheter-Associated Urinary Tract Infections (CAUTIs).


  • CAUTIs are the most common type of nosocomial (hospital-related) infection
  • About 23% of patients in US hospitals require the use of a urinary catheter
  • The risk of acquiring a CAUTI increases by about 3-7% each day that an indwelling urinary catheter remains inside the patient
  • These infections cause more than 13,000 deaths in the United States every year, and also create over $400M worth of increased costs to the care facilities that have to pay for treatments, etc. resulting from the CAUTI.


The clients for this urinary catheter re-design project were made aware of this healthcare problem by a relative who is currently a medical student. As a well-known issue with urinary catheters, Dr. John Crepeau and George Tanner of the University of Idaho were compelled to present this problem with the hopes of creating a new urinary catheter that would prevent harmful CAUTIs, spare thousands of lives, and save millions of dollars for the healthcare industry.

2018 IPUC stats.png

Value Proposition[edit]

Currently, in the medical field, CAUTIs are perceived as an inevitable illnesses. Team Infection protection focuses on CAUTI prevention to give patients and healthcare workers peace of mind.

Deliverable[edit]

Develop a catheter design that will reduce bacterial growth and build-up within the urinary tract. The design must be manufacturable on a large scale basis, and it must be adaptable in size.

Specifications[edit]

  • The catheter shall allow for quick and easy insertion, anchoring, and removal. The anchor shall deploy once inserted in the bladder. At no point prior to removal shall the catheter slip from the bladder due to an anchor failure. Upon removal, the anchor shall be quickly and carefully released, leading to a smooth catheter withdrawal.​
  • The design must employ a mechanism which will allow solution/antibiotics to be pumped through the catheter to flush out the bladder and the urethra in order to prevent bacteria from building up, and consequentially causing an infection. Additionally, there must be a port and channel with the ability to connect/disconnect to a pump or syringe system which will be used to inject the system-flushing fluid.
Project Specifications
Design Area Specification
Design Metrics
  • Design must have a scalablity range of 12-26 Fr (1 Fr = 1/3 mm).
  • Design should support a urinary flow rate of 4 mL/s or more.
Patient Metrics
  • Including the time to carefully anchor the catheter within the bladder, insertion should take 45 seconds or less.​
  • The Coefficient of friction between the outer catheter surface and urethra tissue should be 0.2 or less.
  • Insertion force shall not exceed 1.12 lbs (5 N).

Design Considerations[edit]

2018 IPUC foleys.png

The 2-way Foley catheter seen above is the most common indwelling urinary
catheter. A single catheter can be used over a duration range of a couple
hours to 90 days.

The 3-way Foley catheter is less common. It is primarily used with
patients that have already contracted an infection within the bladder.
This catheter allows healthcare professionals to send medicine directly
to the bladder for infection treatment.

Project Learning[edit]

Design Concepts[edit]

Concept Advantages and Disadvantages
Embedded Spiral

2018 IPUC embeddedspiral.png

Pros:
  • No change to traditional profile​
  • Same procedure for insertion/removal​
Cons:​
  • No space creation for fluid flow​
  • Requires higher pressure for irrigation fluid discharge​
  • Increased difficulty of manufacturing
Outer Spiral

2018 IPUC outerspiral.png

Pros:​
  • Creates space for fluid to flush urethra​
  • Only one irrigation point at top​
Cons:​
  • Possible discomfort to patient​
  • Added surface area for bacteria growth
  • Displeasing profile​ which may be more difficult to market

Understanding the Root Cause of Infection[edit]

While using a catheter, a patient will become more susceptible to bacterial encroachment. The body has a natural defense to UTIs through recurrent urination throughout the day. A catheter inhibits the flow of urine in direct contact the urethra. Instead, urine flows intraluminally through the waste channel, and the urethra is left stagnant.

The anatomy of the human body leads to heightened risks of infection. Escherichia coli (E. coli) is the most common type of bacteria that causes UTIs. The E. coli typically migrates from the anal cavity to the external urethral orifice (opening). Once the bacteria has entered the urinary tract, it can spread all throughout the urethra to the bladder, and if not treated, into the bloodstream.

Early Prototyping Methods[edit]

Dip Method

2018 IPUC dip.png

Team Infection Protection began the prototyping process with a liquid latex dipping method. The team dipped a metal rod into the latex multiple times to form the features from inside-out.
Drawbacks to this Method
  • The liquid latex cures to the shape of the dipped item. This made it difficult for the catheter to be made into a uniform cylindrical shape with the addition of the other features (balloon channel, irrigation channel, ports, etc.).
  • The high viscosity of the latex increased layer thickness drastically. This made prototyping to a specific diameter challenging
3D Printing Method

2018 IPUC 3dprint.png

To better obtain the detailed features, the team transitioned to prototyping with the flexible 3D print filament, Thermoplastic Polyurethane (TPU). Unlike the more common filaments, this 3D print material is flexible. This method yielded a visually appealing catheter.
Drawbacks to this Method
  • The layers of TPU were not printed in close enough proximity to the previous layer. Because of this, the catheter was not operable, due to its inability to hold liquid. Syringed fluids simply bled through the walls of the catheter.
  • 3D printing is not an ideal method for mass production

Chosen Design (preCAUTIon Catheter)[edit]

Composition[edit]

This design features 3 ports and 3 distinct channels. The largest channel is for waste drainage. The remaining two channels are the same size, with one being for the balloon anchor, and the other for urethra irrigation.The outer profile of the catheter includes a spiral to create space within the urethra.


Image: 400 pixels

How It Works[edit]

The catheter was designed to bio-mimic the natural bodily function, urination. To do so, the design allows for an irrigation solution to be injected into the appropriate irrigation port. The flushing solution travels through the catheter tube up to the base of the balloon, where the fluid is released to the urethra. The fluid then spirals down and out of the urinary tract, while maintaining contact with the maximum urethral tissue surface area.
Image: 400 pixels

Validation[edit]

2018 IPUC validation1.PNG

Flow Test[edit]

The flow test visually demonstrates how the urethra is irrigated to flush bacteria from the urinary tract. To set up this test the preCAUTIon Catheter was inserted into clear tubing so the test could be easily observed.

  • The red dye in the surrogate urethra represents bacteria
  • The blue liquid represents irrigation solution
  • As the blue liquid is syringed into the catheter, and is released to the urethra, the fluid turns dark and purple
  • When the "bacteria" has been completely flushed from the urethra, the liquid runs clear and blue
2018 IPUC flow.gif

Bacteria Test[edit]

2018 IPUC BacSetup.PNG
To conduct the bacteria test, it was important that the human body was simulated to allow for adequate bacterial growth. To simulate the body environment the following were executed:


  • LifeLike BioTissue Urethras were used. "The LifeLike Urethra closely simulates the urethra and the tissue cuts, feels, sutures and behaves live real live tissue"
  • The urethras were deposited into wet containers, and sealed to trap moisture.
  • A heating element was utilized to maintain the container temperature at 98.6°F


Testing Procedure
Both a commercially available Foley catheter and the preCAUTIon Catheter were coated with live E. coli before being inserted into the surrogate urethras. The Foley catheter sat stagnant throughout the duration of the test. However, the preCAUTIon Catheter was flushed once daily with 0.9% saline solution. After 6 days, both catheters were swabbed and the contents from the catheter were deposited onto nutrient agar petri dishes.


Results
The "cloudy" streaks on the control plate indicate substantial bacterial growth on the Foley catheter. The few spots on the experiment plate demonstrate the preCAUTIon Catheter's ability to effectively remove bacteria from the urethra.
2018 IPUC Bacteria.PNG

Insertion Test[edit]

Healthcare professionals expect full catheterization is attainable without exceeding an applied force of 1.12 lbf (5N) to the catheter. The key components used for the insertion test were a catheterization model and a force gauge. The insertion test was conducted with a commercially available Foley catheter and the preCAUTIon Catheter. The following steps describe the testing process:

Testing Procedure

  • String was attached to each catheter
  • The catheter was adequately lubricated
  • The catheter was passed through the catheterization model and the maximum force was recorded
  • The preceding steps were performed 5 times and the average of the 5 trials was documented


Results
This test indicated that the required insertion force for the preCAUTIon Catheter is greater than the common Foley catheter. However, the experimental force value is nearly a quarter of the maximum recognized value of 1.12 lbf.

2018 IPUC InsertSetUp.png
2018 IPUC Insert.PNG

Manufacturability[edit]

How the Foley Catheter is Made[edit]

  1. The first step in the manufacturing of a Foley catheter is the production of the long, thin tube that will be inserted into the bladder. The liquid rubber silicone is poured into a room temperature vulcanization (RTV) rubber mold. The mold is shaped like the desired catheter with either two or three outputs.
  2. The silicone is then heat cured. This procedure can take anywhere from 0.5 to 40 hours. Once cooled, the tube is withdrawn from the mold.
  3. A small opening is then punched in the distal end of the tube furthest away from the two outputs.
  4. A thin band of cured latex is slipped over the tube by hand to form a sheath around the tube. It is positioned so that the latex covers the opening that has been punched in the tube.
  5. To form the balloon, the entire length of the tube is dipped in latex, which creates an overcoat layer and bonds the band to the tube proximate to the distal and proximal ends of the band, forming the balloon. This adds to the thickness of the balloon and is used to adjust the outer diameter of the tube to the desired size.
  6. The catheter is then transported to the packaging center where it is put into a kit with a needleless syringe (to fill the balloon) and a drainage bag
Read more about catheter production here

Slight Change in the Manufacturing Process[edit]

2018 IPUC inject.png
To produce the prototype shown in the picture to the right, the following steps were performed:


  1. The catheter mold file was created in SolidWorks
  2. The mold was 3D printed with Polylactic Acid (PLA) filament
  3. 2-part silicone mix was well-stirred and vacuumed to removed air bubbles.
  4. The silicone mix was injected into the mold to cure for 18 hours

The steps to form the balloon were also completed.

2018 IPUC mold.png
To produce the preCAUTIon Catheter on a large scale, the only projected adjustment in the manufacturing process would be to alter the mold in which the silicone is poured. The remaining steps will remain the same.

Project Conclusion[edit]

  • The innovative design allows for the removal of harmful bacteria from the urinary tract​
  • The preCAUTIon Catheter Provides a relatively atraumatic insertion, with potential to make removal less traumatizing than it currently is
  • The design can be easily manufactured based on current practices​
  • Additional testing is required to further assess the design

Team Members[edit]

Team Infection Protection[edit]

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2018 IPUC teamphoto.JPG
2018 IPUC ed.jpg
Ed Hall

Major: Mechanical Engineering
Hometown: Chugiak, Alaska
Graduation Date: May 2019
Future Goals: Ed aspires to devise green solutions that will have positive effects on both the world and the people in it.
Email: hall2189@vandals.uidaho.edu


2018 IPUC amy.jpeg
Amy Macias

Major: Biological Engineering
Hometown: Nampa, Idaho
Graduation Date: December 2019
Future Goals: After completing her undergraduate degree, Amy hopes to ultimately start a career innovating medical equipment to keep up with the ever changing modern world.
Email: maci8945@vandals.uidaho.edu


2018 IPUC elena.jpg
Elena Tipton

Major: Mechanical Engineering
Hometown: Fruitland, Idaho
Graduation Date: May 2019
Future Goals: After graduation, Elena will start her career working as an engineer for Hewlett-Packard.
Email: tipt4166@vandals.uidaho.edu


Additional Documentation[edit]

Project Schedule

File:2018 IPUC Schedule.pdf

Meeting Agenda

File:2018 IPUC Agenda.pdf

Meeting Minutes

File:2018 IPUC Meeting Minutes.pdf

Presentations

File:2018 IPUC PreliminaryPresentation.pdf
File:2018 IPUC ConceptDesignReview.pdf
File:2018 IPUC Engineering Release Review.pdf
File:2018 IPUC EXPO.pdf

Budget

File:2018 IPUC Budget.pdf