Steve Warren

A wearable point-of-care system for home use that incorporates plug-and-play and wireless standards

A point-of-care system for continuous health monitoring should be wearable, easy to use, and affordable to promote patient independence and facilitate acceptance of new home healthcare technology. Reconfigurability, interoperability, and scalability are important. Standardization supports these requirements, and encourages an open market where lower product prices result from vendor competition. This paper first discusses candidate standards for wireless communication, plug-and-play device interoperability, and medical information exchange in point-of-care systems. It then addresses the design and implementation of a wearable, plug-and-play system for home care which adopts the IEEE 1073 Medical Information Bus (MIB) standards, and uses Bluetooth as the wireless communication protocol. This standards-based system maximizes user mobility by incorporating a three-level architecture populated by base stations, wearable data loggers, and wearable sensors. Design issues include the implementation of the MIB standards on microcontroller-driven embedded devices, low power consumption, wireless data exchange, and data storage and transmission in a reconfigurable body-area network.

Applying the ISO/IEEE 11073 Standards to Wearable Home Health Monitoring Systems

Objective. The goal of this effort was to investigate the feasibility of applying the ISO/IEEE 11073 (a.k.a. X73) standards, originally intended for bedside monitoring in hospital environments, to wearable, multi-sensor monitoring systems designed for home healthcare. Methods. The X73 upper-layer sub-standards (i.e., nomenclature specification, domain information model, application profiles, and vital sign device descriptions) were adopted and implemented on microcontroller-based sensor hardware to provide plug-and-play medical components. Three types of system elements (base stations, data loggers, and sensor units) perform the functionality required in this standards-based home health monitoring system and communicate using Bluetooth wireless modules. The base station incorporates a LabVIEW interface running on a personal computer. Each data logger and sensor unit is implemented on a microcontroller-driven embedded platform. Sensor units include wearable sensors (e.g., electrocardiograph, pulse oximeter) and nearby sensors (e.g., weight scale, ambient environment sensors). Results. The standards-based prototype system with an open architecture achieves plug-and-play performance suitable for a home environment. Each wireless element in the body/home area network can automatically detect other nearby devices, associate with them, and exchange data with them as appropriate. Conclusions. With minor modifications, the X73 standards can be successfully applied to wearable, wireless, point-of-care systems in the home.

Interoperability and Security in Wireless Body Area Network Infrastructures

Wireless body are networks (WBAN) and their supporting information infrastructures offer unprecedented opportunities to monitor state of health without constraining the activities of a wearer. These mobile point-of-care systems are now realizable due to the convergence of technologies such as low-power wireless communication standards, plug-and-play device buses, off-the-shelf development kits for low-power microcontrollers, handheld computers, electronic medical records, and the Internet. To increase acceptance of personal monitoring technology while lowering equipment cost, advances must be made in interoperability (at both the system and device levels) and security. This paper presents an overview of WBAN infrastructure work in these areas currently underway in the Medical Component Design Laboratory at Kansas State University (KSU) and at the University of Alabama in Huntsville (UAH). KSU efforts include the development of wearable health status monitoring systems that utilize ISO/IEE 11073, Bluetooth, Health Level 7, and OpenEMed. WBAN efforts at UAH include the development of wearable activity and health monitors that incorporate ZigBee-compliant wireless sensor platforms with hardware-level encryption and the TinyOS development environment. WBAN infrastructures are complex, requiring many functional support elements. To realize these infrastructures through collaborative efforts, organizations such as KSU and UAH must define and utilize standard interfaces, nomenclature, and security approaches

Wearable sensors and component-based design for home health care

Recent technology trends indicate that truly cost-effective home health care systems of the future will be constructed from distributed, plug-and-play, commodity components assembled on-the-fly to match the needs of a given patient. This paper describes early efforts in the Medical Component Design Laboratory: a research and teaching laboratory where component technologies developed for research will support student projects in closely related engineering courses. Two component-based prototypes are presented in this paper: a Bluetooth-enabled personal monitoring system and a plug-and-play pulse oximeter.

Wearable sensor system for wireless state-of-health determination in cattle

Wearable systems for human and animal state-of-health determination share many design requirements. This paper discusses the design of a remote health monitoring system for cattle that hosts a suite of sensors and communicates wirelessly with a base station via Bluetooth telemetry.

An open test bed for medical device integration and coordination

Medical devices historically have been monolithic units — developed, validated, and approved by regulatory authorities as stand-alone entities. Modern medical devices increasingly incorporate connectivity mechanisms that offer the potential to stream device data into electronic health records, integrate information from multiple devices into single customizable displays, and coordinate the actions of groups of cooperating devices to realize “closed loop” scenarios and automate clinical workflows. However, it is not clear what middleware and integration architectures may be best suited for these possibly numerous scenarios. More troubling, current verification and validation techniques used in the device industry are not targeted to assuring groups of integrated devices. In this paper, we propose a publish-subscribe architecture for medical device integration based on the Java Messaging Service, and we report on our experience with this architecture in multiple scenarios that we believe represent the types of deployments that will benefit from rapid device integration. This implementation and the experiments presented in this paper are offered as an open test bed for exploring development, quality assurance, and regulatory issues related to medical device coordination.

A Short Study to Assess the Potential of Independent Component Analysis for Motion Artifact Separation in Wearable Pulse Oximeter Signals

Motion artifact reduction and separation become critical when medical sensors are used in wearable monitoring scenarios. Previous research has demonstrated that independent component analysis (ICA) can be applied to pulse oximeter signals to separate photoplethysmographic (PPG) data from motion artifacts, ambient light, and other interference in low-motion environments. However, ICA assumes that all source signal component pairs are mutually independent. It is important to assess the statistical independence of the source components in PPG data, especially if ICA is to be applied in ambulatory monitoring environments, where motion artifacts can have a substantial effect on the quality of data received from light-based sensors. This paper addresses the statistical relationship between motion artifacts and PPG data by calculating the correlation coefficients between arterial volume variations and motion over a range of stationary to high-motion conditions. Analyses indicate that motion significantly affects arterial flow, so care must be taken when applying ICA to light-based sensor data acquired from wearable platforms

Design of a plug-and-play pulse oximeter

Presents the design of a plug-and-play pulse oximeter that communicates with a LabVIEW virtual instrument. The sensor module samples plethysmographic data and sends them to a personal computer via an RS-232 serial link. The system configuration is described, and the response of the system is discussed when either the computer, sensor, or RS-232 connection breaks down. The oximeter is suitable for home use and can reliably collect pulsatile data from multiple body locations (e.g. finger, forehead, palm, etc.).

A novel algorithm to separate motion artifacts from photoplethysmographic signals obtained with a reflectance pulse oximeter

Pulse oximeters are mainstays for acquiring blood oxygen saturation in static environments such as hospital rooms. However, motion artifacts prevent their broad in wearable, ambulatory environments. To this end, we present a novel algorithm to separate the motion artifacts from plethysmographic data gathered by pulse oximeters. This algorithm, based on the Beer-Lambert law, requires photoplethysmographic data acquired at three excitation wavelengths. The algorithm can calculate venous blood oxygen saturation (S/sub v/O/sub 2/) as well as arterial blood oxygen saturation (SaO/sub 2/). Preliminary results indicate that the extraction of the venous signal, which is assumed to be most affected by motions, is successful with data acquired from a reflectance-mode sensor.

Implementation of a standards-based pulse oximeter on a wearable, embedded platform

This paper addresses software design considerations in implementing the medical information bus (MIB) standard on a wearable pulse oximeter. Underlying hardware constraints greatly influence software operation and performance. This design uses a PIC18 microcontroller with software written in C. A modified version of an MIB software implementation by Alaris medical systems will run on this hardware/software configuration. A hardware prototype has been created, and the underlying software is currently in development.