Introduction

Oxygen promises pervasive computing will make the world a better place. The Scalable Medical Alert and Response Technology Project (SMART) [1] project examines deploying Oxygen technologies in the waiting area of an Emergency Department to wirelessly monitor vital signs and locations of otherwise unattended patients. This will give waiting patients some security that their condition is being monitored even though a caregiver is unavailable. The Emergency Department caregivers will be alerted to problems occurring in the waiting room in real-time, while alerts and patient priorities can be dynamically adjusted depending on the circumstances. We hope to gain some insights from this Emergency Department deployment with goal of being able to quickly deploy this system in disaster situations where patients drastically outnumber available caregivers.

Approach

In this project we plan to monitor patients in the waiting room who have an initial complaint of chest pain. We will give each patient a handheld computer and two sensors. The sensors, which will be monitoring the electrical rhythms of the heart (ECG) and the oxygenation levels (SpO2), will send their data to the patient's handheld. The handheld will forward the data to a central server. The central server will monitor the signals and alert appropriate caregivers when there is a problem. The system will also have an indoor positioning system, such as Cricket [2], for locating patients, caregivers, and equipment.

Progress

During the past year we built a prototype of this system. The prototype has four components: a wearable patient monitor, a central computer, a caregiver interface and a tracking system. The patient monitor is based on an HP iPAQ model 5500. This PDA interfaces to a sensor box. The sensor box provides physiological signals from a 1-lead ECG sensor and an SpO2 sensor to the PDA. The sensor box also gives the PDA location information from a Cricket listener. The PDA forwards this data wirelessly to the SMART Central computer.

The SMART Central computer analyzes the patient data for alarm conditions. Alarm conditions include high heart rate, low heart rate and low SpO2. When an alarm condition is detected, it is dispatched to an available caregiver.

This prototype system also gives each caregiver a PDA. These PDAs allow the caregivers to see the roster of patients and to click through to see a patient's vital signs in real-time. The caregiver's PDA also has a Cricket listener so that SMART Central can track caregivers. The PDAs built-in vibration feature is used to alert the caregiver PDA has received an alarm.

To achieve our goals for tracking patients and caregivers, we are using the Cricket location system. This system consists of beacons and listeners. Each beacon is placed on a wall and emits RF messages indicating the beacon's location. The beacon also emits ultrasound chirps. The cricket listeners are attached to the patients' and caregivers' PDAs. The listeners report the difference in the time of arrival of the RF and ultrasound messages from each beacon they can hear. SMART Central uses this information to figure out where the patients and caregivers are.

We submitted two papers and a demo proposal to the AMIA 2005 conference.

Future

During the upcoming year, we plan to deploy this system in an actual emergency room and evaluate its acceptance by patients and caregivers. We will also evaluate our sensor and platform choices, given the ongoing improvements in the available technologies. We have ongoing research projects in the following areas: real-time analysis of mobile ECG signals, managing energy consumption on tiny wireless sensors, transmitting vitals signs data and video from an ambulance via a cellular network, asset tracking, and alarm management.

Research Support

This research is supported by the National Library of Medicine, Acer Inc., Delta Electronics Inc., HP Corp., NTT Inc., Nokia Research Center, and Philips Research under the MIT Project Oxygen Partnership, and CIMIT, the Center for the Integration of Medicine and Innovative Technology.

References:

[1] Lucila Ohno-Machado and Dorothy Curtis. Smart: Scalable Medical Alert and Response Technology.

[2] Nissanka B. Priyantha, Anit Chakraborty, Hari Balakrishnan, The Cricket Location-Support system, Proc. 6th ACM MOBICOM, Boston, MA, August 2000. http://cricket.csail.mit.edu