April 9, 2004BME 272/2731 Investigation of Bubble Formation in Tuohy-Borst Adaptors Department of...
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Transcript of April 9, 2004BME 272/2731 Investigation of Bubble Formation in Tuohy-Borst Adaptors Department of...
April 9, 2004 BME 272/273 1
Investigation of Bubble Formation in Tuohy-Borst Adaptors
Department of
Biomedical Engineering
Melanie Bernard, Isaac Clements, & Jason Hirshburg
Advisor: Ted Larson III, M.D.
April 9, 2004 BME 272/273 2
Problem Statement• Bubbles are seen within the Tuohy-Borst Adaptor
– Origin/cause unknown
• Consequences– Can get stuck in small arteries, inhibiting blood and oxygen to the brain– Causes stroke in 0.1% of procedures (bubbles > 1ml)
• Accessory Problems– Bubbled are hard to remove; they stick to inner surface of tubing/adaptor– Occurs in adaptors of different length, angle of arm– May be from multiple sources
http://www.cookurological.com/products/ureteroscopy
April 9, 2004 BME 272/273 3
Problem Definition• Find the cause of the bubbles and correct it!– Constraints
• Solution must apply to all adaptor types• Any system changes must not significantly change adaptor cost or the catheterization
procedure.• Must eliminate problem without introducing new ones
– Limitations• Time – 6 months• Money – have only a
reasonable budget.• Equipment – don’t have access to blood or ultra- sound machines
www.urmc.rochester.edu/strong/ cardio/cathlab.htm
April 9, 2004 BME 272/273 4
Background• Dr. Larson has 15 years of experience in
interventional neuroradiology
• Catheter uses:– Angiography– Embolization of arteriovenous fistulas– Aneurysms– Preoperative embolization of neck and
intracranial tumors
• Bubbles are consistently observed in catheterization procedures (but have not been formally documented by Dr. Larson).
• Dr. Larson reverses flow 3 times without bubbles before proceeding.
www.angiodynamics.com
April 9, 2004 BME 272/273 5
Background cont.• Bubble Traps– Used when blood is
routed outside the body with pumps
• Cost Analysis– $45k/procedure
• $25k Radiology• ~4-6 min. to clear bubbles• ~3 hour procedure• =$700!!
http://www.laboratoryglassapparatus.com/parts_bubbletrap.gif
http://www.convergenza-online.com/dbt.htm
April 9, 2004 BME 272/273 6
Market Potential
• Target group– Operating rooms worldwide
• Will meet customer needs– Catheterization procedures will be safer
• Is technologically feasible– Physical principles and/or methods can be changed to eliminate
bubble formation
• Is economically viable– Adaptor costs should not rise after our changes
– Could save up to $700 per procedure (not including saving money that would be lost for inducing a stroke)
April 9, 2004 BME 272/273 7
Primary Objective• Our task is to discover the cause of bubble formation and
correct it
• Observations from Dr. Larson’s procedures: Bubbles…– Up to 10-20% of tube diameter– Stick to inner surface of
adaptor– Appear at the edge of the Y-junction– Occur before microcatheter is inserted– Typically occur when catheter flow is reversed and blood hits the edge
of the Y-junction and interfaces with the saline
April 9, 2004 BME 272/273 8
Previous Work• Observed device in a medical
procedure on 11/18/03
• Literature Search
• Innovation WorkBench (revised 3/2)
• Conducted experiments– Primary: tested equipment– Secondary: simulated pressures
and temperatures of entire system
– Tertiary: testing individual components to different conditions
• Filmed procedures on 2/2/04 and 3/31/04; obtained new supplies
• Performed calculations based on actual and worst-case scenario parameters
April 9, 2004 BME 272/273 9
Possible Sources of Bubbles1. Leaks
From 3-way valve
From rotating hemostatic valve
Between adaptor and catheter
2. Introduced during adjustments
In flushing process
Injecting contrast agent
Reversing fluid flow
3. AdaptorAngle of arm causes local pressure dropMicrobubbles pool at connections
4. Temperature differences
N2, O2, or CO2 coming out of blood
Air coming out of saline
5. Initial flushing processIn catheterIn saline tubePulling back saline syringe
6. SalineAir coming out of solutionPushed into system by pressure bagHigh flow rate and interaction with bloodPressure drop from 250 – 0 mmHg
7. Pressure change for N2, O2, & CO2 in blood
Local pressure drop at diameter change
Pressure drop across catheter
Pressure drop from 100 – 0 mmHg
April 9, 2004 BME 272/273 10
Experiments Conducted• Primary Experiments:
– Observed many bubbles throughout system
• Secondary Experiments:– Blood pressure = 120/80 (mmHg)– Saline pressure = 250 mmHg– Blood temp = 98.6 F– Saline temp = room
• Tertiary Experiments:– Tested connections for leaks
• 35 degree catheter turn
– Air solubility in saline under pressure (250 mmHg)
– Tested catheter for bubbles after flushing
– Tested bubble occurrence after syringe pull-back
April 9, 2004 BME 272/273 11
Videotaping the proceduresWe videotaped the bubble phenomenon during two actual procedures in Dr. Larson's operating room:
The first videotape was created on 2/24/04 with a standard VHS video camera.
We acquired a high resolution digital video camera to videotape a second procedure on 3/31/04.
April 9, 2004 BME 272/273 12
Videotape Analysis
Observations:
•There are many bubbles forming!
•Out of 4 minutes of footage, we recorded 15 bubble occurrences.
•Bubbles appear to be coming from within the catheter
•In 14 out of 15 cases, the bubbles appear under set conditions:
1. Saline is flowing forward into the catheter
2. The 3-way valve is opened and flow is reversed
3. Bubbles appear immediately and seem to be coming from within the catheter.
April 9, 2004 BME 272/273 13
Current & Future Work
• In a meeting with Dr. Larson, we laid out our final goals for the project, including:– Determining all possible sources of bubbles – Ruling out as many as possible through our observations,
calculations, and experiments.– Taking the remaining possibilities and determining the
likelihood of each theory.– Create a final analysis of the most likely cause.– Give suggestions for improving the situation.
• We have researched the following catheter clearing methods:– Wetting agents– Dynamic Bubble Traps (DBTs)– Degassing saline before injection (and heat?)
April 9, 2004 BME 272/273 14
Acknowledgements
Dr. Ted Larson and staff Dr. Paul King
Dr. Joan WalkerDr. Robert RoselliDr. Todd Giorgio
Dr. Cynthia PaschalDr. Rick HaseltonDr. Bob Galloway
Matt Lytle for his services as cameraman.
We would like to thank the following professionals and experts for their input:
April 9, 2004 BME 272/273 15
BibliographyCatheter Flushing, Bubble Formation within Catheters, Dynamic Bubble Traps, Wetting Agents:
http://www.ajnr.org/cgi/content/full/22/4/709http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=
http://www.convergenza-online.com/dbt.htmhttp://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/
http://www.bandwidthmarket.com/resources/patents/apps/2001/5/20010001111.html
Manufacturing Links for Tuohy-Borst Adaptors:http://www.cordis.com/logc/active/crdus/en_US/html/cordis/downloads/Product_Catalog.pdf
http://www.cookurological.com/products/ureteroscopy/5_06/5_06_06.htmlhttp://www.fda.gov/ohrms/dockets/ac/03/briefing/3993b1_CLiRpath-peripheral-IFU-revE-10.pdf
Images for Catheter Insertion Procedure:
http://www.angiodynamics.com/tips.htm
Interventional Neuroradiology Links:http://www.csmc.edu/2725.html
http://neurosurgery.mgh.harvard.edu/interventional/http://www.okxray.com/aneurysm_coiling.htmhttp://www.emedicine.com/radio/topic870.htm
http://www.carotidarterystenting.com/Articles/Article1.htm
April 9, 2004 BME 272/273 16
Questions…?
Visit our website at http://vubme.vuse.vanderbilt.edu/srdesign/2003/group17/
www.cookurological.com/.../ureteroscopy/ 5_06/5_06_06.html