Pain Stimulator

1. PREVIOUS DEVICE IMPROVED DEVICE Screening and Questionnaires 5 Min. Resting BP Assessment Assess Barorecptor Sensitivity (BRS) 15 Min. Seated Rest 5 Min. Seated Rest Insert Cannula Assess Emotions (EAS) Plasma Sample Drug Infusion Over 10 Min. 30 Min. Adaptation 20 Min. Seated Rest Assess EAS and Side Effects Plasma Sample Insert Finger Adjust & Apply Pressure 5 Min. Rest Assess BRS: 5 Min. Seated Rest LabVIEW collects data for 1 minute, data is saved and exported for future statistical analysis Pain Stimulator Bryan Eckerle1, Katharine McFadden1, Adam Platt1, Elizabeth Slyziuk2, Jennifer Wells1 Advisors: Paul King, Ph.D.1 and Stephen Bruehl, Ph.D.3 1Vanderbilt University Department of Biomedical Engineering 2Vanderbilt University Department of Mechanical Engineering 3Vanderbilt University Medical Center Department of Anesthesiology PROBLEM STATEMENT Dr. Bruehl’s main objective is to understand endogenous pain regulatory mechanisms in humans, with particular interest in the relationship between blood pressure, acute pain sensitivity, and chronic pain. He is currently studying the effects of Yohimbine, a selective α-2 adrenergic receptor antagonist, to understand the role of the adrenergic system in regulation of pain pathways. He is using a device based on the original Forgione-Barber Finger Pressure Stimulatorto stimulate C-fibers. The device has a fixed amount of weight attached to a lever with an unknown amount of pressure being applied to the dorsal surface of the second phalanx of the index finger. It is mounted on a table that does not allow for adjustments to accommodate variance in subject height or forearm length. Additionally, the system does not include an electronic output. The administrator asks the subject for a numerical pain rating on a scale from 0 to 100, anchored with “no pain” and “worst pain imaginable,” thus creating a numerical bias. Our objective is to create an adjustable, electronically integrated, and standardized acute pain stimulus to compare responses under placebo and under blockade of various receptors. SYSTEM SCHEMATIC EXAMPLE OF PREVIOUS DATA Subject Number 008 NO GRAPHICAL OUTPUT Reported Pain Level: 30, 50, 65, 90 MANUAL DATA ENTRY NECESSARY Circuit sensitivity = .6V/cm @ Vs=5V Potentiometer sensitivity = 1500Ω/cm RESULTS Potentiometer Circuits DEVICE PC Computer LabVIEW 7.1 USB DAQ NI 6009 Contact Switch Circuit APPROACHES CONSIDERED Vibration, thermal and electrical stimuli were considered, but ultimately rejected in order to maintain pressure stimulus of C-fibers. A pneumatic pressure device was also considered, but rejected for the stable and reliable lever system already in place. • ADDITIONAL EQUIPMENT • National Instruments LabVIEW Version 7.1.1 • National Instruments USB-6009 Data Acquisition Device • Mouser Electronics 60mm Linear 10k Taiwan Alpha Slide Potentiometer • PROJECT DELIVERABLES • Modified version of Forgione-Barber Finger Pressure Stimulator • Software for data acquisition • Vertically adjustable medical table • Sliding scales to eliminate number bias • Integrated system: device mounted to table, connected to sliding scale and software CONCLUSION Design specifications were met so that the experiment is adjustable for subject variance, automated, and electronically integrated. The study is improved as a result. EXPERIMENTAL PROCEDURE IMPROVED EXPERIMENTAL PROCEDURE Screening and Questionnaires 5 Min. Resting BP Assessment Assess Baroreceptor Sensitivity (BRS) 15 Min. Seated Rest 5 Min. Seated Rest Insert Cannula Assess Emotions (EAS) Plasma Sample Drug or Placebo Infusion Over 10 Min. 30 Min. Adaptation • IMPROVEMENTS • ELECTRONIC OUTPUT using LabVIEW 7.1 • Automated Timer Digital Data Storage • Digital Display Ability to Export data for further statistical analysis • Graphical Output Automated Start of Data Acquisition (contact switch) • Audiovisual Cues • Adjustability • Hand Dominance Forearm Length • Subject Height Adjustable Weight Applied directly over Contact Point • Pain Reading • Linear Potentiometers eliminate numerical bias 20 Min. Seated Rest Assess EAS and Side Effects Plasma Sample Insert Finger Adjust & Apply Pressure 5 Min. Rest Assess BRS: 5 Min. Seated Rest 15s Manual Data Entry & Analysis 15s 15s 15s Numerical Pain Rating Numerical Pain Rating Numerical Pain Rating Numerical Pain Rating