Wireless Smart Sensors An emerging technology that will transform healthcare

1
Wireless Smart SensorsAn emerging technology
that will transform healthcare
Jim Welch, CTO, Welch Allyn Monitoring Nat Sims
MD, Partners Healthcare Rick Hampton, Partners
Healthcare
IEEE September 2004
2
What is the need?
Patient care is becoming increasingly complex

• Hospital systems capacity is at or near limits
• Length of stay reduction is approaching
  diminishing return
• Minimally invasive therapies are migrating from
  acute care facilities to out-patient or minimal
  stay facilities
• Existing monitoring devices are too costly and
  complex to become broadly applied

care is moving from Hospital to Home
AND
Health care must shift the hospital to the home
to meet the ever increasing demands for lower
costs and improved outcomes
3
American Heart Statistics
a compelling need

• 63 Million Americans have cardiovascular disease
• 1.1 Million heart attacks each year
• 540,000 deaths each year
• Approx. half in hospitals and a quarter of these
  are unmonitored
• Survivability in home 5, hospital 55, airport
  with AED 80

• Estimated cost to hospitals for unwitnessed
  cardiac code is between 15K-25K due to
  increased LOS (13.4 days for resuscitated
  patients)
• Survivability in hospitals 38 if defibrillated
  within 3 min, 21 if longer

4
from the Hospital to the Home
The Acuity Slope

• 30 of Nurses
• 80 of Resource Consumption
• 5 of Patients

Shifting Innovation Down the Acuity Slope

• 70 of Nurses
• 20 of ResourceConsumption
• 95 of Patients

5
Innovate down the continuum of care
Technology Disruption Trajectory
General Care
lt100
6
What is a smart sensor
The future of monitoring technology

• Body worn, comfortable to wear
• Information reduction within the sensor (e.g.
  waveforms to numerics and alarms)
• EC13 Compliant
• Pacemaker detect (HW)
• Untethered connectivity
• Preferably to an existing infrastructure
• Long life (1-3 days)
• Automatic detection and notification of
  clinically significant event
• Much lower cost than existing, traditional
  sensing methods

7
Making smart sensors possible

• Moores Law driving smaller, less expensive and
  lower power microprocessors
• Emergence of low cost SOC
• Emergence of inexpensive bi-directional standards
  based radio technologies
• Advances in materials for use in sensors.
• World wide proliferation of wireless
  infrastructure

Technology Convergence
8
Addressing an unserved market
Clinical Applications

• Non-monitored bed
• US estimate 460,000 non monitored acute care beds
• ED surges
• Mass casualty applications
• Homeland defense
• Military
• Hostile environments
• Home

9
Smart Sensor System Overview
System Architecture

• Low cost, limited feature on-body sensor
• Wireless Personal Area Network
• Patient worn wireless gateway
• Client / Server
• Wireless Local Area Network (WLAN) or (WAN)
• Clinician carried respondent device

Patient-Worn Devices
Sensor
Gateway
802.15.4
802.11b
Server
802.11b
Clinician-Worn Devices
10
Sensor Characteristics

• Worn anywhere on upper left chest (over heart)
• Continuous analysis of single channel ECG
• AAMI EC 13 compliant
• Full pacemaker detection
• Additional channels can be achieved by placing
  more sensors on the body in appropriate
• Transmitts ECG sample upon alarm or request
• Proprietary disposable electrode (3 days)
• Single patient use
• Integrated disposable battery
• Patents pending

11
Smart Sensor Architecture
Radio 1-2mA
Analog 1-1.5mA
Digital 2-4mA
Power Source 2 ea 2035 coin cells at 3V
12
Wireless networks
Respondent Device
Sensors
Gateway
Server
WBAN
WLAN / WAN
WLAN / WAN
13
Technology challenges
Mitigating the Risks

• Battery life
• Sensor 1-3 days (skin wearability)
• Gateway 5 days (average length of stay)
• Signal quality
• Shorter distance between electrodes
• False alarms from motion artifacts
• Network reliability

14
Electrode Placement Study
Comparison of signal amplitude vs. electrode
distance
Study conducted through ASE Saturday Academy
15
Experimental Results
Challenging historical assumptions
Study conducted through ASE Saturday Academy
16
Artifact Comparisons Tooth brushing
Sample Smart Sensor Signal
17
Sample Smart Sensor Signal
Artifact Comparisons Walking
18
Noise Metric Measurements
Quantifying the Noise
Right Hand Tooth Brushing
Study conducted through ASE Saturday Academy
19
less false alarms

Subject Standard Nightingale
Andrew 4 5
Chris 25 0
Emma 7 0
Greg 8 0
Jim S 0 0
Katya 2 0
Lorraine 28 7
Craig 5 0
Suzanne 0 1
Rob 19 3
David 3 1
Shawn 7 2
Lisa 12 3
Jim 6 0
Steve 4 2
Sum 130 24
Percentage 84.4 15.6
Comparison of false postive alarms
20
Conclusions

• End to end low cost smart sensor systems are
  achievable
• Closely spaced electrodes can provide sufficient
  performance to meet clinical and regulatory
  requirements
• Optimization of electrode configuration and
  placement can result in improved measurement
  reliability (lower false alarms) in highly
  ambulatory applications