CA2333255A1

CA2333255A1 - A medical measuring system

Info

Publication number: CA2333255A1
Application number: CA002333255A
Authority: CA
Inventors: Gaby Bader
Original assignee: Individual
Current assignee: Biosys AB
Priority date: 1998-05-15
Filing date: 1999-05-17
Publication date: 1999-11-25
Also published as: US6171264B1; AU4405399A; ATE264651T1; EP1077632B1; AU752978B2; DE69916599T2; WO1999059460A2; EP1077632A2; JP2002515274A; DE69916599D1; WO1999059460A3

Abstract

Cellular radiotelephone communication systems and methods downlink digital coded speech from a cellular radio exchange to a cellular radiotelephone base station and uplink downsampled (i.e. undersampled relative to the Nyquist rate of two samples per symbol) radiotelephone signals from the cellular radiotelephone base station to the cellular radio exchange. The downsampled radiotelephone signals are demodulated at the cellular radio exchange and the digital coded speech is modulated at the cellular radiotelephone base station.
Diversity demodulation may be used at the cellular radio exchange, to diversity demodulate the downsampled radiotelephone signals at the cellular radio exchange. By downlinking digital coded speech from the cellular radio exchange to the cellular radiotelephone base station, and uplinking downsampled radiotelephone signals from the cellular radiotelephone base station to the cellular radio exchange, narrowband uplinks and downlinks may be provided between the base stations and the cellular radio exchange, to thereby reduce cost. Moreover, since demodulation takes place at the cellular radio exchange rather than at the base stations, low cost base stations may be provided. However, since downsampled radiotelephone signals are transmitted from the base stations to the cellular radio exchange, diversity demodulation may be performed at the cellular radio exchange, to thereby improve the voice quality of the cellular radiotelephone communications.

Description

bV0 99/59460 PCT/SE99/00834 A MEDICAL MEASURING SYSTEM
TECBNICAL FIELD
The present invention relates to a medical measuring system and in particular to a method and a system for portable measurement, surveillance, transmission recording and analysis of physical, physiological and other functions and parameters.

In various medical areas it is sometimes necessary to perform measurements and surveillance during long periods of time.
Examples of such medical areas could be neurology, cardiology, telemedicine, long-term nursing and home nursing.
During such long-term measurements, which typically last for days, the patient must at all time be connected to the measuring equipment in order for a continuous measurement to occur.
Furthermore, in most cases such measurements must be supervised by qualified personnel in order to prevent interruptions in the measurements and to check that the condition of the patient does not worsen. The latter is very important since measurements of the kind mentioned above often are included in treatment as follow-up examinations or in investigations for establishing a diagnosis. Thus, it is common that the person responsible for correctly carrying out the measurements is a doctor.
These long term measurements must therefore be carried out using ambulatory measurement equipment, since the patient can hardly be expected to remain in bed during the long periods required for obtaining a continuous series of measurements.
Further, the measuring equipment must be located at a hospital in order to there be supervised by a doctor in charge.
This is of course expensive for the payer of the hospital care and not particularly comfortable for the patient who WO 99!59460 PCT/SE99/00834

2 cannot leave the hospital despite the fact that he/she is not in any need of hospitalization at the movement.

It is an object of the present invention to reduce the costs resulting from long-term measurements.
It is another object of the present invention to improve the environment and reduce the difficulties for patients who need to undergo long-term measurements.
It is yet another object of the present invention to provide a measuring pad for measurements of physical and physiological parameters, which is very sensitive and which therefore can be located at a fairly long distance from a patient, for example beneath a thick mattress or even under a bed.
It is a further object of the present invention to provide a pre-amplifier, which is easy to handle and which produces or eliminates the risk for erroneous handling, and which is suited to be used together with the measuring equipment.
These objects and others are obtained by means of a method and system by means of which the measurements can be carried out at a distance from a hospital. Thus the patient is connected to a measuring system comprising measuring sensors and a unit for collecting data comprising a transmitter. The unit for collecting data preferably also comprises means for performing different analyses. The system also comprises a centrally located surveillance unit.
The measuring sensors sense various physical and physiological parameters, for example brain activities, actions of the heart, respiration, blood pressure, blood values/tests and body movements. The sensed signals are transmitted to a portable small device of low weight for collecting and/or analysing data, which is connected to a

3 central surveillance unit, for example via the public switched telephone network (PSTN), a radio system, in particular a cellular radio system, or via a satellite communication. The central surveillance unit is monitored by qualified personnel which can follow the measurements and also in certain cases reprogram the unit for collecting and analysing data during an ongoing measurement.
In a preferred embodiment the measuring sensors comprise a preamplifier having an identification circuit. The identification circuit is used for providing each preamplifier with a unique identity. The fact that each pre-amplifier is given a unique identity makes it possible for the unit collecting and analysing data to automatically check if the correct pre-amplifier has been attached to the correct input terminal and, if that is not the case, either correct the error or give a signal indicating that an erroneous connection has been made.
In yet another preferred embodiment a measuring pad for measuring physical and physiological parameters is provided.
The measuring pad comprises a film having piezo and/or pyro electrical characteristics, for example a PVF-film (Poly Vinyl Fluoride), or any other sensor having similar properties. By using such a film, which can convert movements into an electrical signal several advantages are achieved.
Thus, a measuring pad comprising such a film is easy to fold together and can be made very sensitive, whereby it can be placed beneath the mattress or even under the bed in which the patient is lying.
Furthermore, the signals transmitted to/ from the central surveillance unit can be image/video signals (if a camera is connected to the system), audio signals (such as speech), text signals (for transmission of prescriptions etc.) as well as biological signals. In this manner the personnel at the surveillance end of the system can have full access to information required for providing the patient with proper medical treatment at distance.

4 The use of the system as described herein provides a number of advantages compared to the prior art. Thus, the patient no longer needs to be in a hospital but can instead be at home or at an another suitable location. Hence, by using the system the cost for hospital care is reduced or eliminated.
Furthermore the patient can move around freely due to the ' fact that the measuring system and auxiliary equipment used for collecting data are made small and of low weight.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described more in detail and with reference to the accompanying drawings, in which:
- Figure 1 is a schematic view of an ambulatory medical measuring system:
- Figure 2 is a schematic diagram of a unit for collecting and analysing data.
- Figure 3 is a schematic diagram of a preamplifier used in the medical measuring system shown in figure 1.
- Figure 4 is a section through a measuring pad for use together with the medical measuring system shown in figure 1.
DETAILED DESCRIPTION
In figure 1 a schematic diagram of an ambulatory medical measuring system is shown. Thus a unit 1 for collecting and analysing data is connected to a measuring pad 2 and a pre-amplifier 3. The measuring pad 2 and the preamplifiers 3 sense different physical and physiological parameters and are described in more detail below in conjunction with figure 3 and figure 4. These signals are transmitted to the unit 1 for collecting and analysing data.
In the unit 1 the signals provided by the measuring pad 2 and the preamplifiers 3 are A/D-converted and stored and analysed. The digital data stored in the unit 1 can then be output from the unit 1 to an external computer 4.
The transmission of data to the external computer 4 can be carried out in a number of different ways. In a preferred embodiment the transmission is carried out using an infrared IR-interface. Such an arrangement has the advantage that the patient can be connected to the measuring equipment when data is transmitted from the unit 1 to the computer 4 without being physically connected to the computer 4. Thus, the risk

5 for electrical current to be transmitted from the computer 4 to the patient is eliminated.
In another preferred embodiment the unit 1 is also provided with, e.g., a PCMCIA-card or PC-card or a similar device by means of which the unit 1 can connect to a telephone or data network. The computer 4 then does not need to be in the same room as the unit 1 when data is transmitted from the unit 1 to the computer 4. For example, the unit 1 can be located together with the patient at home and the computer 4 can be located at the hospital.
A doctor or another qualified person at the hospital can then connect to the unit 1 at any time and transmit measurements data from the unit 1 via for example the public switched telephone network or a cellular network to the computer 4. In such an arrangement the patient does not need to be disturbed or even know about when the unit 1 transmits data and must hence not be bothered by this.
In yet another preferred embodiment the unit 1 can in itself analyse the collected measurement data. Examples of analyses which the unit 1 can perform are comparisons between measured signals and threshold values corresponding to such signals.
Thus, an alarm can be activated in the unit 1 if such a threshold value is crossed either from above or from below and the computer 4 can be automatically contacted via the telephone or data network in order for the doctor or qualified personnel monitoring the computer 4 to immediately have access to all measurement data, in particular the data causing the triggering of the alarm.
In this manner an important event in the series of measured data can be spotted quickly, transmitted and possibly taken

6 care of. For example, the information transmitted can form the basis for moving the patient to a hospital in order to perform more thorough investigations and tests or that an emergency alarm is issued and that actions required are performed.
Another advantage achieved with such an arrangement is that it is possible to perform adjustments in the settings at distance. Thus, if the doctor or qualified personnel for one reason or another wants to measure some another physical or physiological parameter, which at present is not being measured, information thereof can be transmitted from the computer 4 to the unit 1 and collection of the new desired parameter can start in the unit 1.
In yet another preferred embodiment data regarding the patients earlier conditions and possible treatment can also be stored and transmitted to/from the unit 1. The unit 1 may also be equipped with a GPS-navigation system for continuous surveillance of the movements of the patient and in order to locate the patient quickly in the case an alarm signal is transmitted and the patient must be located quickly.
In fig. 2 a schematic block diagram of the unit 1 is shown.
Thus, the unit 1 comprises an input terminal 10 for analogue signals and an input terminal 12 for digital signals. The analogue input terminal is connected to a unit 14 wherein the signal is amplified and filtered. The output signal from the unit 14 is fed to an A/D-converter 16 wherein the signal from the unit 14 is converted into a digital format.
The output signal from the A/D-converter is fed to a _ computation and control unit 18. The signals input at the terminal 12 are also connected to the unit 18. The unit 18 is connected to a memory 20 in which information can be stored and from which the unit 18 can read information. The unit 18 is also connected to a unit 22 arranged to transmit and receive information from outside the unit 1. . The unit 22 can for example be a wireless modem or another suitable

7 interface.
The unit 1 can further comprise a power supply unit 24, for example a rechargeable or replaceable battery. In a preferred embodiment the power supply unit comprises a back-up function so that a battery can be charged or replaced without having to interrupt an ongoing measurement.
The unit 1 may also have an input terminal 26 to which equipment for control, calibration or analysis of the unit 1 can be connected.
In Fig. 3, a schematic block diagram of the pre-amplifier 3 is shown. Thus, the pre-amplifier 3 comprises a first amplifier 103, which is connected to a number of input terminals arranged to receive plug-in contacts for electrodes, which are attached to a person from whom measured data are collected.
The amplifier 103 is connected to a digital filter 105. The filter 105 filters the signals using a suitable filter. The filter may by different for different types of signals as described below.
The filter 105 is in turn connected to a second amplifier 107 wherein the signals are amplified a second time to a suitable output amplitude. The amplifier 107 is connected to an output terminal through which the pre-amplifier 3 can be connected to the unit 1. The pre-amplifier 3 can also be equipped with a wireless interface towards the unit 1. If such an arrangement is employed the need for cables and input/output terminals can be dispensed with.
Furthermore, the pre-amplifier 3 comprises an identification and calibration unit 109. The unit 109 can communicate with the unit 1 or with another external unit via a bi-directional data communication line. Thus, the unit 1 can read a unique ID-number and also, in a preferred embodiment, read calibration data stored in the unit 109.

8 In a preferred embodiment the ID-number and the calibration data can be read continuously or every time the pre-amplifier is connected to the unit 1.
IN another preferred embodiment the pre-amplifier 3 can be informed of which type of signal which is to be measured.
This is accomplished by means of a special protocol, which informs the pre-amplifier that a particular type of signals are to be measured, for example heart or bzain signals.
Since the pre-amplifier is informed of which type of signals that are to be measured the filter 105 can be adjusted for that type of signals and also the amplifiers 103 and 107 can be set to levels, which are suitable for the type of signals to be measured.
Since each pre-amplifier 3 is given a unique identity the unit 1 can sense if the correct pre-amplifier has been connected to the corresponding input terminal of the unit 1.
If this is not the case, the unit 1 can correct the mistake or give a signal informing the user of his/her mistake.
Furthermore, since the unit 1 and/or the pre-amplifier 3 has knowledge of which type of signal that is to be measured, an alarm signal can be issued if the wrong type of signal is measured.
In Fig 4, a section through the measuring pad 2 is shown. The pad 2 comprises a pressure sensitive element 201 made of a material such as a PVF-film or another type of film, which generates an electrical voltage in response to physical _ movements or pressure changes. Around the element 201 a protective coating 202 is arranged.
The coating 202 isolates the element 201 from static voltages and other electrical noise. The pad 2 is preferably further provided with a shock absorbing material 3, which protects the element 201 from impacts. The material 3 is preferably a rubber material or another suitable flexible and robust

9 material.
The pad 1 has an outer coating made of a water resistant material 204, which prevents liquid from getting into contact with the pressure sensitive element 201. The element 201 can further communicate with the unit 1 via a cable 205, which is connected to the unit 1 and to the element 201. The cable 205 is passed through the outer coating 204 of the pad 2 through a watertight passage.
l0 In another preferred embodiment the interface between the unit 1 and the pad 2 is wireless. The element 201 then emits signals to the unit 1 via a wireless modem or via infrared (IR) light, or in any other suitable manner.
A portable system as described herein can be made of very low weight and the measuring parts of the system, i.e. the electrodes and its pre-amplifier(s), and the measuring pad, are therefore easy to bring along when a patient using them wants to move around. This gives the patient much more freedom than what can be achieved with the prior art.

Claims

CLAIMS:

1. A portable medical measuring system comprising:
- a plurality of sensors for measuring physiological parameters of a patient, - a data collecting unit comprising a memory for storing data corresponding to a long-term measurement and connected to the sensors for receiving signals from the sensors, the sensors and the data collecting unit being portable and mountable on a person, and - a surveillance unit located at distance from the data collecting unit and communicating over a bi-directional communication line with the data collecting unit, the memory in the data collecting unit thereby being accessible from the surveillance unit, and means provided for remotely controlling which of the multitude of parameters to be measured at a particular time.

2. A system according to claim 1, wherein the data collecting unit also is arranged to measure physical parameters.

3. A system according to claim 1, wherein the data collecting unit comprises means for analysing collected data.

4. A system according to claim 3, wherein means for issuing an alarm signal are connected to the analysing means.

5. A system according to claim 1, wherein the surveillance unit is arranged to transmit control and set-up signals to the data collecting unit.

6. A system according to claim 1, wherein the collecting unit comprises a GPS-transmitter for transmitting a position signal to the surveillance unit for continuously monitoring the position of the patient.

7. A system according to claim 1, comprising a signal amplifier device connected to the data collecting unit having an identification circuit for automatic identification of the amplifier.

8. A system according to claim 7, wherein the amplifier device has means for storing calibration data.

9. A system according to claim 7, wherein the amplifier device comprises a signal filter, the parameters of which can be controlled in response to control signal.

10. A system according to claim 1, comprising a pressure sensitive element made of a film arranged to convert pressure changes into an electrical signal and which is connected to the data collecting unit.

11. A system according to claim 10, wherein an elastic material is arranged around the film.

12. A system according to claim 10, wherein the film is made of PVF (Poly Vinyl Fluoride).