Non-Transcranial Non-Transcranial ElectroanesthesiaElectroanesthesia

Group 2Group 2 Students: Students: Ryan DemeterRyan Demeter

Matt JacksonMatt JacksonCaroline ShulmanCaroline ShulmanMatt WhitfieldMatt Whitfield

Advisors: Dr Paul King and Dr James BerryAdvisors: Dr Paul King and Dr James Berry

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Project DefinitionProject Definition

• Design, build, and test a system for both administering and recording data related to vagal nerve stimulation.

• Topics to cover: Project Background, Vagal Nerve Information, Design Ideas, Stimulation (production and application) Techniques, Testing, Current and Overall Status, and BMEidea

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Current Anesthetic TechniquesCurrent Anesthetic Techniques

• Sedationadministered through vein

• Local anesthesialocally numb area

• Regional anesthesiablock pain signals from single nerve bundle

• General anesthesiaComplete unconsciousness

Mayo Clinic

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Proposed New TechniqueProposed New Technique

• Non-invasively electrically stimulating the right and left vagal nerves at the neck level to produce general anesthesia

www.alegent.com/18117.cfm

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Background of ElectroanethesiaBackground of Electroanethesia

• Electroanesthesia can occur by passing electric current through the scalp (Kano et al. 1976)

• Quicker recovery time and less biological effect during and after surgery than gas (Photiades, 218-225)

• Heal better (Sances & Larson, 21-27)• Less of a buildup of gases in the body (Sances & Larson, 218-219)• Few detrimental effects on EEG or ECG (Sances & Larson, 55-58)• Electrolyte levels in extracellular and intracellular fluid of the brain

(Sances & Larson, 148-175)• Decreased gastric acid secretion (Sances & Larson, 33-46) • FDA concerns

• Vagal nerve stimulation (Kirchner et al., Ness et al.)

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• 10th cranial nerve• Location: both sides of the neck• Composition: A, B, and C-fibers• Function: motor and sensory (visceral afferent) signals • Not fully myelinated until adulthood (Koo et al. 429-433)• Parasympathetically innervates pharynx, larynx, lungs, heart, esophagus, stomach, small

intestine, colon• Shown to help control seizures and depression (VNS)• Best route to the central nervous system (Rutecki 1990)

Vagal Nerve InformationVagal Nerve Information

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• A-fibers– Adapt to constant stimulus and exhibit presynaptic

inhibition– Respond well to low stimulus (George et al. s56-s61)– Conduction Speed: 90 to 30 m/s1

– Selectively activated by low intensity VNS– No effect on EEG recorded in the rats studied by

Hammond et al. (1992)

• B-fibers– Respond well to low stimulus (George et al. s56-s61)– Conduction Speed: 20 to 10 m/s1

– No effect on EEG recorded in the rats studied by Hammond et al. (1992)

• C-fibers– Continue to fire with constant stimulus– Conduction Speed: 1.6 to .3 m/s1

– Convey pain signals

Cont…Cont…

[1] Woodbury, DM and J.W. Woodbury. “Effects of Vagal Stimulation on Experimentally Induced Siezures in Rats.” Epilepsia. 31.Suppl. 2 (1990): s7-s19

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Mechanism: efferentMechanism: efferent

• Over-stimulation of vagal nerve can result in faintingParasympathetic innervationsSlows breathing and heart rateReduced O2 to brain » » fainting

Not desired effect!

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Mechanism: afferentMechanism: afferent

• Over-stimulate pain centers in brainTotal loss of consciousness?Loss of pain perception?

• Ideally stimulation needs to be more powerful than VNS, but low enough not to cause efferent effects

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Project BackgroundProject Background

• Currently, electroanesthesia devices are in use in Europe.

• In less developed countries where anesthesia technology is lacking, an electroanesthesia device would reduce both the cost of the procedure and the need for technical personal (anesthesiologist). – S. Leduc – Europe, Japan, Russia, and Germany– Activation of a theoretical pain center – 35 V, 4 mA, 100 Hz, rectangular pulsating signal – Alternative method

• Descending mechanism and the interconnections within the brain

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CostCost– Gas anesthesia

• In the case of gas anesthesia, more is required for treatment and cost are around twenty to forty dollars a patient (Kurpiers et. al., 69-75, VUMC 2006).

– Liquids

• between three and nine times as expensive as gas anesthesia per volume (Kurpiers et. al., 69-75).

– Electroanesthesia will reduce the high cost of anesthesia for surgery and other procedures by reducing the need to keep large quantities of liquid and gas anesthesia on hand.

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Cost cont.Cost cont.

Current

– Monitor including vital signs

• $ 50,000

– The machine• $70,000 for

– Gas• $100 

Ours• vital signs equipment

– $2,000 if added

• The laptop cost – $600

• electrical components – $100

• Electricity– $10.00

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MethodsMethods

• Computer system• Vital signs monitoring equipment• Testing

– Phase I: - Device components connected and tested to assure compatibility-Software integrated and tested to assure compatibility and proper operation-Test inputs and outputs of device

– Phase II: Applicator testing to assure proper outputs and operation

– Phase III: Testing of device operation with a rat

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Design 1Design 1

• Too Complex• Un-needed

components

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Design 2Design 2

• Less Components Needed

• Laptop keyboard eliminates need for an additional keyboard

• Internal components dependent on stimulation method

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Stimulation ParametersStimulation Parameters

• Stimulation of both Vagal Nerves

• 20 Hz Rectangular pulse signal

• Pulse length of 250 µs (Liporace et al. 885-886)

• 50 µA (Kirchner et al. 1167-1171)

• 25 V

• Need to consult more with Dr. Berry to estimate best parameters

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LabVIEWLabVIEW

Old Design• LabVIEW user

interface• DAQ Controller

– Expensive to actually buy DAQ controller

New Design• LabVIEW user

interface• Sound Output

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LabVIEW cont.LabVIEW cont.

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Delivering ElectroanesthesiaDelivering Electroanesthesia

• Gain Stage

- Advantage: Computer compatible

- Disadvantage: Noise, unforeseen circuitry problems

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DetailsDetails

• Sound card (Output only 1 V)– Gain(~25)

• Enclosed Circuitry

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Recent ContactsRecent Contacts

• Ray Booker - Simulation engineer at Ctr. for Medical Simulation

– Discussed head and neck phantoms • Cost• Availability• Function

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Airway ModelAirway Model-Relatively inexpensive (POSITIVE)

-Immediately available (POSITIVE)

-Thin, plastic head and

neck (NEGATIVE)

-No damage from electric shock

(POSITIVE)

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Impedance testingImpedance testing

• Acquire pig head from slaughterhouse– Pig skin has properties like human skin

• Testing phase

• Signal needs to be effective at a thickness of roughly 2 cm

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Patent SearchPatent Search

• #6,393,319 May 21, 2002• Data for electrical waveforms stored on CD • Amplified and conditioned for stimulation via

electrode on the skin

• However….

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Current StatusCurrent Status

• Received grant of $500 to prepare for BMEidea

• Improving and debugging LabView schematic and programming

• Patent search for sound card as a voltage source

• Building gain stage

Overall StatusOverall StatusMonth Description

November 2005Look into previous research done on VNS and Electroanesthesia. Develop schematics

and possible device physical designs. Start design development.

December 2005Proceed with research and finalize our design approach. Assemble basic design

components. Develop software and user interface.

January 2006 Begin designing prototype model and testing.

February 2006Proceed with prototype design and testing. Obtain IRB approval to test our

device as early as possible.

March 2006Run experiments if approved and make modifications where necessary. Continue

work-up and finalize design.

April 2006Continue to finalize Design and prepare paper and presentation poster. Submit

prototype to BMEidea competition.

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BMEideaBMEidea

• Problem objective statement – Develop an applicator and control device for electroanesthesia. Our

device will control and administration electroanesthesia. The device will be portable, self sustaining, and rechargeable.

• Documentation of the final design, including applicable standards and risk analysis

– Class II Medical Device Standards– Design Safe

• Prototype of the final design– In progress

• LabVIEW in form, not function• circuit

– To come• housing

• Proof that the design is functional and will solve the problem – Theoretical

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BMEideaBMEidea• Results of a patent search and/or search for prior art, assessment of patentability

– See above • Anticipated regulatory pathway

– 510(k)– In progress

• Estimated manufacturing costs – See Cost Slide

• Market analysis– market need

• Reduction of anesthesia costs– competitive landscape

• none (European Design)– potential market size

• very large– replace most anesthesia devices

– selling price (undetermined)– reimbursement status (????)

• Business plan detailing strategy for commercialization and opportunity statement– In Progress

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Most Important ReferencesMost Important References10 of 3110 of 31

Ammons, W. Steve, Robert W. Blair, and Robert D. Foreman. "Vagal Afferent Inhibition of Primate Thoracic Spinothalamic Neurons." Journal if Neurophysiology 50.4 (October 1983): 926-940.

Bohning, DE, MP Lomarev, S Denslow, Z Nahas, A Shastri, and MS George. "Feasibility of vagus nerve stimulation-Feasibility of vagus nerve stimulation- synchronized blood oxygenation level-dependent functional MRI." Investigative Radiology 36.8 (2001): 470-479.

Fries, Richard. E-mail interview. 5 2005.

“FDA: Significant Risk and Nonsignificant Risk Devices”. Mount Sinai School of Medicine. 1 September 2005. <http://www.mssm.edu/irb/pdfs/appendix/13.pdf>

Hammond , EJ, BM Uthman, SA Reid, and BJ Wilder. "Electrophysiological studies of cervical vagus nerve stimulation in humans: I. EEG effects.." Epilepsia. 33 (1992): 1013-1020.

Kano, T, GS Cowan, and RH Smith. "Electroanesthesia (EA) studies: EA produced by stimulation of sensory nerves of the scalp in Rhesus monkeys." Anesthesia and Analgesia (1976): 536-541.

Kirchner MD, A., F. Birklein MD, H Stefan PhD, and H.O. Handwerker PhD. "Left vagus nerve stimulation suppresses experimentally induced pain." Neurology 55.8 (2000): 1167-1171.

Melzack, Ronald, and Patrick D. Wall. "Pain Mechanisms: A New Theory." Science 150.3699 (1965): 971-979.

Sances Jr., Anthony, and Sanford J. Larson. Electroanesthesia Biomedical and Biophysical Studies. New York: Academic Press, Inc., 1975.

Woodbury, DM and J.W. Woodbury. “Effects of Vagal Stimulation on Experimentally Induced Siezures in Rats.” Epilepsia. 31.Suppl. 2 (1990): s7-s19