Problem Statement HyDRRA Hydration Determination by Resistance & Reactance Analysis Team Pferck...
-
Upload
howard-stanwood -
Category
Documents
-
view
225 -
download
5
Transcript of Problem Statement HyDRRA Hydration Determination by Resistance & Reactance Analysis Team Pferck...
Problem Statement
HyDRRAHydration Determination by Resistance & Reactance Analysis
Team PferckDouglas J. Hall, Cara G. Welker, Mary Morgan Scott, Rachel-Chloe Gibbs, Skylar C. Haws
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
A
• Dehydration alone causes 518,000 annual hospitalizations and $5.5 billion in charges 1
• Hyperhydration is the most common electrolyte imbalance in hospitals, occurring in about 2% of all patients 2
• Current gold standard: Acute hydration measurements are obtained by invasive swan-ganz catheter placement, which is invasive & impractical and requires trained clinicians to use.
Many clinical disorders correlate with hydration status. However, health care providers have few reliable non-invasive methods for real-time quantification of hydration status in the clinic.
The solution must:• Correlate diagnostic information to changes in hydration status• Assess hydration status in clinical setting without prior background
monitoring• Allow the provider to easily translate/display data• Provide the patient with a noninvasive, unobtrusive and
comfortable product
Bodystat QuadScan 4000• $3,000 retail• Difficult data transfer• No patient data storage• Inconvenient and slow
UI• Results not
communicated in a clinically relevant way
Special thanks to Matthew Walker III ,PhD; Kevin Sexton, MD; Franz Baudenbacher, PhD; James Pietsch, MD; Tracy Perry, and René Harder
Hydration Determination by Resistance and Reactance Analysis
• Human body can be modeled as electrical circuit
• Capacitive elements are frequency dependent
• Obtain impedance data at various frequencies
• Correlate impedance values with hydration status
• Compare to market competitor• Establish improved device and
model for clinical prediction of hydration status
Protocol1. Collect general patient data (height, weight, and
age) from nursing staff2. Sanitize and clean surfaces of skin with rubbing
alcohol and cotton wipes for electrode placement
3. Place electrodes in one of the testing configurations (see right)
4. Record impedances using Bodystat and BIVA devices
5. Repeat step 4 after dialysis treatment6. Remove electrodes and collect post-treatment
weight7. Record total volume of fluid lost during treatment
Bioimpedance Vector Analysis (BIVA) Device
• Digital multifrequency impedance spectrometer
• Frequency scanning range: 5-200 kHz• Wireless data transfer via Bluetooth• 4 Lead Setup: Current source / Voltage
measurementFigure 2. BIVA device developed by Dr. Baudenbacher
Our design• Sleek design• Mobile interface• Wireless data transfer
and cloud storage• More accurate
measurements• Patient data records
Purpose: Correlate impedance changes to fluid volume loss for hydration status algorithm developmentExperimental Population: Dialysis patientsExclusionary Criteria: Congestive heart failure, diureticsIRB Status: Pending after preliminary review
Main Menu Normal Hydration Hyperhydrated
Design: HyDRRA
Needs Assessment
Background
BIVA Device
User Interface & Data Transfer Clinical Study Design
Comparison to Competitor
Preliminary Results
Conclusions & Future Steps
Acknowledgments
Completed• Established detection sensitivity• Designed and submitted clinical
IRB study• Designed GUI for Android
application• Comparison with competitor
Future• Determine indicative test
frequencies and electrode placement regimes
• Develop hydration status algorithm based on study results
• Code Android application
Wrist to Ankle
Transthoracic
Set up device and
place electrodes
Run determined
range of frequencies
Impedance correlated to
hydration based on
established model
Voltage change
converted to impedance
reading
Change in voltage
measured by device
Display hydration status on Android Device
ReferencesProblem: It is challenging to reliably induce a quantifiable amount of water loss or overload outside of the clinical settingSolution: Clinical study in an experimental population that undergoes rapid, quantified fluid loss
Market
1. Kim, S. "Preventable hospitalizations of dehydration: Implications of inadequate primary health care in the United States." Annals of Epidemiology 17.9 (2007): 736.
2. "Overhydration." Gale Encyclopedia of Medicine. 2008. The Gale Group, Inc. 8 Apr. 2014 http://medical-dictionary.thefreedictionary.com/overhydration
3. Wang, Zimian, et al. "Hydration of fat-free body mass: new physiological modeling approach." American Journal of Physiology-Endocrinology And Metabolism 276.6 (1999): E995-E1003.
4. Dunkelmann, Lea, et al. "Estimation of dehydration using bioelectric impedance in children with gastroenteritis." Acta Paediatrica 101.10 (2012): e479-e481.
MEDICALHydration Monitor
MEDICALEMT and ER
Triage
ATHLETICEndurance Sports
MEDICALLong-Term Care
ATHLETICRace Participant
Triage
COMMERCIALPersonal Monitor
0 20 40 60 80 100
120
140
160
180
200
0
5
10
15
20
25
BIVABodyStat
Frequency (kHz)
Imp
ed
an
ce
Dif
fere
nc
e
(Oh
ms
)
Figure 6. A positive impedance change is seen in both the BIVA and BodyStat over all frequencies after weight loss of at least one pound during workout (n=3)
0 50 100 150 2000
0.51
1.52
2.53
3.54
Before Overhydra-tion
Mid Over-hydration
After Overhy-drationBefore Dehydra-tionAfter De-hydration
Frequency (kHz)
Pe
rce
nt
Dif
fere
nc
e (
%)
Figure 7. A greater difference is seen between the BIVA and BodyStat devices at more hydrated states, but the difference between the two devices is still relatively small
Dehydration Protocol (n=8): Subjects exercised without rehydrationOverhydration Protocol (n=4): Subjects drank 1/100 of their body weight every hour for 12 hours
Figure 1. The body can be modeled as an electrical circuit
Figure 3. GUI for an improved Android application. Main menu (Left), healthy results (Center), and hyperhydrated results (Right) are shown.
Figure 4. Process flowchart outlining the function of the device
Figure 5. Bodystat and BIVA devices
Figure 8. Dialysis overview
Figure 9. Bowling pin diagram for market capture. Courtesy of Anna Rose Kelsoe.