UV Light Wand for Elimination of Bacteria Found in Pediatric

Endotracheal Tubes Team Members:Sarah Hodges Matthew SundermannJeffrey Turner Sarah Williams

Advisors

• Neal Maynord, MDPediatric Critical Care FellowMonroe Carell Jr. Children's Hospital at Vanderbilt

• Ty Berutti, MD, MS, MSAssistant Professor, Pediatric Critical CareMonroe Carell Jr. Children’s Hospital at Vanderbilt

Other Correspondents• James Harrington- Rutgers University, fiber optics

expert, mostly IR but some UVJames A. HarringtonDepartment of Material Science and EngineeringRutgers University

jaharrin@rci.rutgers.edu

• Prof. Yuji Matsuura at Tohoku University in Japan-Contact given to us by Dr. Harrington DOKO Engineering- Japan

info@do-ku.sakura.ne.jp

Problem Statement

• Ventilator Associated Pneumonia (VAP) is the second most common infection acquired by patients in the pediatric ICU

• 20% of nosocomial infections in the PICU can be identified as VAP

• Need a more efficient way to clear bacteria from pediatric endotracheal tubes to prevent VAP

Effects of VAPVAP Cause

of VAP

Extended mechanical ventilation

Bacterial build-up in endotracheal

tube

4 Day Extension of hospital stay

Increased cost of care ($40,000

per patient)

Increased mortality rate

Silver Nitrate Coated Endotracheal Tubes Reduce but Do Not Eliminate Bacterial Colonies

• STUDY: ▫ 12 of 21 bacteria populations the silver coated

endotracheal tubes reduced bacterial counts ▫ 7 the counts stayed constant ▫ 2 (specifically Enterobacter aerogenes and

Enterobacter cloacae) the colony count rose• A more effective method of eliminating bacteria

is necessary

UV Light Effectively Eliminates Bacterial Colonies Present in VAP

• E. coli is generally representative of a wide range of Gram negative bacteria

• High intensity UV light of wavelength 200-300 nm causes effective inactivation of the bacteria

• Maximum inactivation of E. coli occurs at 270 nm

Ultraviolet Radiation Safety Concerns• UV-C (100 -280 nm) cannot penetrate the dead

layer of human skin, but can burn the cornea• UV-C kills bacteria• No regulatory limits but the American

Conference of Governmental Industrial Hygienists (ACGIH) publishes Threshold Limit Values (TLV) ▫ 250 mJ/cm2 at 180 nm and 3.1 mJ/cm2 at 275 nm

• UV light can be blocked by opaque surfaceshttp://www.americanairandwater.com/UV-pdf/ultraviolet-radiation-safety.pdf

Primary Objective

• Design a device using UV technology to reduce the occurrence of VAP in pediatric patients

Secondary Goals • Device goals ▫ Effectively kill bacteria ▫ Fit through a 3mm diameter pediatric

endotracheal tube ▫ Flexibility sufficient to travel down the entire

length of an endotracheal tube • Build a prototype of the device • Test prototype to determine safety (Amount of

UV light allowed to escape from the endotracheal tube) and efficacy against bacteria

Solution Description • UV light source coupled to a hollow optical waveguide with an

internal aluminum coating

• UV light travels down the length of the hollow waveguide and is emitted from the end

• UV light strikes either reflection or scattering system and irradiates sides of the endotracheal tube ▫ May occlude up to 80% of the tube for about 15 seconds at the time

• Irradiation kills the bacteria in the tube

• Silicon tube and silver tube lining used to protect patient from UV radiation

Solution Description

UV Light Source

Hollow Waveguide

Reflection/ scattering System

UV Light Source • The LEDMOD Series- High

Power Fiber Coupled LED Modules ▫ Omicron Laser, Germany ▫ Deep UV wavelengths

available without fiber coupling

▫ Allow coupling of hollow waveguides

• Other UV LED options• Laser ▫ Potentially too expensive

• Water sterilization system ▫ Inexpensive option

http://www.omicron-laser.de/english/led-modules/ledmod-lab/led-mod-lab.html

Hollow Optical Waveguides • Traditional optical fibers are

not an option for transmitting UV light ▫ Traditional materials absorb

UV light

• Solution: Hollow Optical Waveguides ▫ Hollow core filled with air

(inert gas)- absorption loss in the core eliminated

▫ Aluminum thin-film coating on the inside of a capillary tube Doko Engineering LLC

Performance Criteria and Other Design Considerations • Compatibility constraints▫ Solution must be suitable for pediatric applications▫ Patient must be protected from harmful UV light

• Cost and Reusability Constraints▫ Protective sheath on any device desirable for efficiency

• Effectively eliminate bacteria ▫ A sufficient amount of light must reach the bacteria

Pediatric Endotracheal Tubes- 3 mm diameter minimum

J. Pediatr. (Rio J.) vol.79 suppl.2 Porto Alegre Nov. 2003

Pediatric Endotracheal Tubes- Radius of Curvature

• Radius of curvature for larger (7mm) ETT > 15 cm

• Waveguides may not be suitable for smaller ETT

• Future work on this device could include thinner, more flexible waveguides as they are available

Silicon and Silver Protect the Patient from UV Light

• A study on contact lenses found UV-C light is significantly blocked by silicone ▫ ETT are typically silicone

• The silver coating on the inside of the silicone ETT provides an extra barrier to UV light▫ Photometer testing

• Need to ensure no UV light escape from the end of the tube

Laube et.al. 2004

Loss of Light-Factors

• Internal coating of the hollow waveguides ▫ Aluminum was found to

minimize this loss

• Bending of the waveguide

• Efficiency of coupling between the UV light source and waveguide

Matsuura et. al. 2004

Performance Metrics

• Success determined by: ▫ Size appropriate prototype completed ▫ Photodetector indicates no UV light escaping

from the endotracheal tube▫ Bacterial cultures eliminated

BudgetItem Cost Supplier Description

4 Silver Lined Endotracheal Tubes

$20 each *4 = $80 To be determined Silver nanoparticle lined endotracheal tubes.

2 Small UV light emitter $100 each *2 = $200 Bass Pro Shops UV light emitter designed for water purification. To expose inside of tube to kill bacteria.

Hollow Waveguides (1mm)

$200 each Doko Engineering Purpose is to transmit light from UV light emitter down endotracheal tube

Total: $480 Budget subject to change as project progresses

Cost-Benefit AnalysisPrototype Costs:

• $200 UV light waveguide• $50 in waveguide

modificantions• $300 UV light source-this cost

will be shared between all patients who use

• Total Cost: $550

Benefit:

• $10,000 average extra cost for each case of VAP

• Conservatively if we are 50% effective the benefit to each possible patient is $5,000

• About 27% of ICU patients are infected with VAP. Final benefit per patient will be $1,350

Future Work

• Order/ purchase materials for prototype

• Locate UV light detector

• Build prototype

• Test prototype against bacteria

References Laube T. Apel H. Koch HR. Ultraviolet Radiation Absorption of Intraocular Lenses.

Opthamology. 2004. 111:880-885.

Matsuura Y. Harrington JA. Optical Properties of Small-bore Hollow Glass Waveguides. Applied Optics. 1995. Vol. 34 No. 30.

Matsuura Y. Miyagi M. Hollow Optical Fibers for Ultraviolet and Vacuum Ultraviolet Light. IEEE Journal of Selected Topics in Quantum Electronics. December 2004. Vol 10 No. 6.

Matsuura Y. Miyagi M. Hollow Waveguide for Ultraviolet Light and Making the Same. United States Patent. October 2000.

Rello J. et. al. Activity of a Silver Coated Endotracheal Tube in Preclinical models of ventilator-associated pneumonia and a study after extubation. Crit Care Med. 201 0 Vol 38 No. 4.

Wang T. et.al. Pulsed ultra- violet inactivation spectrum of Escherichia coli. Water Research. 2005 Vol. 39: 2921-2925.