EmerLoc: Location-based services for emergency medical incidents

Abstract

Background

Recent developments in positioning systems and telecommunications have provided the technology needed for the development of location aware medical applications. We developed a system, named EmerLoc, which is based upon this technology and uses a set of sensors that are attached to the patient's body, a micro-computing unit which is responsible for processing the sensor readings and a central monitoring unit, which coordinates the data flow.

Objective

To demonstrate that the proposed system is technically feasible and acceptable for the potential users.

Method

Transmission speed is assessed mostly by means of transmission of DICOM compliant images in various operational scenarios. The positioning functionality was established both outdoor using GPS and indoor using the UCLA Nibble system. User acceptability was assessed in a hospital setting by 15 physicians who filled in a questionnaire after having used the system in an experimental setting.

Results

Transmission speeds ranged from 88 kB/s for a IEEE 802.11 infrastructure to 2.5 kB/s for a GSM/GPRS scenario. Positioning accuracy based on GPS was 5–10 m. The physicians rated the technical aspects on average above 3 on a 5-point scale. Only the data presentation was assessed to be not satisfactory (2.81 on a 5-point scale).

Conclusion

The reported results prove the feasibility of the proposed architecture and its alignment with widely established practices and standards, while the reaction of potential users who evaluated the system is quite positive.

Introduction

The healthcare industry continues to seek the ideal computing platform to serve caregivers. As the computer-based patient record system expands to support more clinical activities, healthcare organizations are asking physicians and nurses to interact increasingly with computer systems to perform their duties. Existing systems suffer from a number of shortcomings including lack of mobility, bulky and obtrusive hardware and lack of flexible functionality. Personal digital assistants (PDAs) represent a new category of devices, starting to be commercially deployed on healthcare and seem to better match the caregiver's needs by adopting the mobile computing paradigm [1].

In the era of mobile computing the trend in medical informatics is towards achieving two goals: the availability of software applications and medical information anywhere and anytime and the invisibility of computing; computing modules are hidden in multimedia information appliances [2]. Mobile computing applications are often made of collaborative parts spread over network components like computing devices, sensors and actuators [3]. As devices and users move from one location to another, applications must adapt to new environments served by heterogeneous networks. Furthermore, mobile applications are characterized by adaptation of their functionality subject to their current environment. Such environment may refer to the physical location, orientation or a user profile. In a wireless-mobile environment, changes of location and orientation are frequent. Sensing the identity and location of the user, through devices like GPS receivers or GSM handsets, is quite important both for security reasons and intelligently adapting user services according to the profile/location of the user. Mobile applications require dynamic forming of wireless ad hoc networks and on-the fly system configuration. The dynamics of such systems are complex because they require not only system reconfiguration and low level configuration, but also service discovery and monitoring in order to provide the best available services. The introduction of Bluetooth and IEEE 802.11 WLAN technology, along with the 2.5G/3G networks, provide a sufficient technology basis for the construction of such “intelligent medical environments”.

In this paper we describe a ubiquitous application, middleware and network infrastructure for handling emergency incidents in random locations either in a controlled environment (e.g., hospitals) or in sites where immediate health support is not possible (e.g., urban areas). The system is intended for patients suffering from chronic diseases or requiring continuous monitoring of their physical condition due to recent health problems. The pre-requisites for the proposed infrastructure are summarized below:

• The patient wears (or carries) a personal device capable of monitoring his vital signals (i.e., ECG, blood pressure, heart rate, breath rate, oxygen saturation and perspiration), processing them and transmitting alarm signals (along with the recent vital signs) whenever predefined thresholds are exceeded and an emergency situation is imminent. Personal devices could be PDAs, mobile phones, communicators, etc.

• The patient's attendant doctor carries a portable device (PDA or Tablet PC) capable of receiving the alarm signals and the full range of the patient's biosignals. Such device is also capable of retrieving, upon request, data from the patient's medical record relevant to the vital signal that initiated the alarm.

• Communication flow is controlled/coordinated by a patient central monitoring unit (CMU), possibly located within a hospital, which acts as a Network Operation Center (NOC). Such unit has full access to the patient's medical record, is capable of receiving vital signals, and intelligently relaying such information to the attendant doctor. Moreover, the CMU can correlate the present location of both the doctor and the patient and provide specific guidance to the doctor on how to reach the patient.

The paper is structured as follows. Section 2 discusses the state of the art in wireless communications for the development of mobile medical applications and patient telemonitoring systems. Section 3 outlines the architecture of the proposed platform while Section 4 describes, in more detail, the distinct modules comprising the system. In Sections 5 System operation description, 6 The system in practice, we present the system operation in practice along with the application results and, finally, Section 7 concludes the paper.