Pain Stimulator

Adam Platt Jen Wells

Biz Slyziuk Kalee McFadden

Bryan Eckerle April 13, 2004

Dr. Stephen Bruehl

Research Interests Endogenous Pain Regulatory Systems,

Psychobiology of Emotions Focus: Understanding endogenous pain

regulatory systems and dysfunction associated with chronic pain.

Interaction between cardiovascular and pain regulatory systems to maintain homeostasis during painful stimuli compared to interaction in chronic pain patients

Blood Pressure

A5 Cell GroupNE Neurons and

α-2 receptors

Rostal Ventrolateral Medulla

NE Neurons and α-2 receptors

Caudal Ventrolateral

MedullaNE Neurons

Rostal Ventromedial Medulla

α-2 receptors

IntermediolateralCell Column

(SNS Preganglionic Neurons)

PeripheralSNS Terminals(α-2Presynaptic Autoreceptors)

Primary Afferent Fiber Terminals α-2 Presynaptic

Dorsal HornLaminae I-IV

α-2 Postsynaptic

Nucleus Tractus Solitarius

NE Neurons and α-2 receptors

Baroreceptor Input

PeriaqueductalGray

α-2 receptors

Locus CoeruleusNE Neurons and

α-2 receptors

Nucleus Raphe Magnus

Spinal Sites of Descending Modulation

Experimental Importance

NIH funded 120 subjects Two research sessions one week apart Stimulation of C-fibers Placebo vs. drug

Measures level of activity of receptors Draw conclusions on natural pain

systems in humans

Experimental Method

Dinamap Compact-T automated oscillometric BP monitor

Finapres 2300 ECG Cannula inserted into dominant arm Blood drawn to assess natural stress hormones

and inflammatory substances Forgione-Barber Finger Pressure Stimulator McGill Pain Questionnaire

Drugs to be Tested

Yohimbine Blocks 2 adrenergic receptors which inhibit release

of norepinephrine Used clinically for erectile dysfunction (orally) For Dr. Bruehl’s purposes, the FDA has only

approved injections

Naloxone Blocks opiate receptors Used clinically for heroine overdose Injected into patient

Problems with Existing Device

No electronic output Oral reading

No accurate measurement of pressure

Lever system with constant weight

No adjustability for height or hand dominance Adjustable only for finger

placement

Our Design

Device

Maintain lever system

Most stable design

Reposition weight to be placed vertically above finger

Adjustable Weight

2 – 5 lbs

Contact Point

Between top two joints on index finger of dominant hand

Middle Phalanx #2

Our Design… Cont.

Table Provided by Dr. Bruehl Transportation Positioning

Adjustable Height Sliding Tracks Forearm length

Slider scale mounted to table displaying “No Pain” to “Worst Pain Imaginable”

Scale mounted on each side of device

Device

(Pressure Transducer)

Slider Scale

A/D Converter

PC Computer

LabVIEW

Schematic

Device with Measurements

Materials

Aluminum Lucite Steel

Device Construction

In process Featheringill machine shop

LabView

Timer Sliding Scale Digital Display Graphical Output Audiovisuals Digital Data Storage

Patient Administrator Date Experimental Data

LabVIEW Interface

Potentiometers

Circuit sensitivity

≈ .62V/cm @ Vs=5V

Potentiometer sensitivity

≈ 1500Ω/cm

Questions?