reliable clinical monitoring using wireless sensor networks: experience in a step-down hospital unit...
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Reliable Clinical Monitoring using Wireless Sensor Networks: Experience in a Step-down
Hospital Unit
Yetta
Outline
• Introduction• Monitoring system• Clinical study• Clinical deterioration detection• Conclusion
Introduction
• Clinical deterioration detection• ICU / step-down unit / general care unit
• IEEE 802.15.4 / IEEE 802.11
• Heart rate (HR) and blood oxygenation (spO2)
Monitoring System
• TelosB / OxiLink pulse-oximeter
Monitoring System
• CTP (collection tree protocol)– Low reliability because of user mobility
• DRAP (Dynamic Relay Association Protocol)– Isolate the mobility from multi-hop routing• Single-hop to first relay• Relay to base station
node cost to root
B 2
C 2
D 1
E 0
E
D
CB
neighbor table of node A
A
Monitoring System
• Radio power management• Sensor component (OxiLink pulse-oximeter)– Control by TelosB– average over 8 sec
• Logging component– Batching flash writing
Clinical Study
• 1200m2
• 18 relays• 41 patients• Pulse and oxygenation were measured at 30-
and 60-second intervals
Reliability
• Network reliability• Sensing reliability
• Time-to-failure • Time-to-recover
Network Reliability
Mean = 22.4 min
95% <2.5 min
Sensing Reliability
• Significantly affected by patient movement, sensor disconnections, sensor placement, and nail polish
Improvement of Sensing Reliability
• Oversample
• Median reliability: 84%(30sec), 75%(60sec)
Median = 1.81 min 75% < 1 min => short burstLong-tailed => sensor disconnection
Improvement of Sensing Reliability
• Disconnection alarms
Clinical Deterioration Detection
Clinical Deterioration Detection
• CUSUM algorithm– detecting statistically significant changes in a
series of measurements– Sliding window
Conclusion
• High network reliability• System reliability dominated by sensor
reliability– Oversampling– Disconnection alarms
• Show the potential of real-time detection of clinical deterioration
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