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.