WO2001032075A2

WO2001032075A2 - Cellular transmission of physiologic data

Info

Publication number: WO2001032075A2
Application number: PCT/IL2000/000704
Authority: WO
Inventors: David Rubin; Shmuel Zinger
Original assignee: Aerotel Medical Systems (1998) Ltd.; Natali - The Israel Company For Emergency Medical Services Ltd.
Priority date: 1999-11-01
Filing date: 2000-11-01
Publication date: 2001-05-10
Also published as: WO2001032075A3; IL132680A0; AU1172501A; IL132680A

Abstract

A method of transmitting physiologic signals data using a speech channel of a cellular telephone, comprising: selecting a frequency band which is not affected by speech compression of a transmission protocol of said speech channel; generating an acoustic signal in said frequency band, which signal encodes said physiologic signals data; transmitting said acoustic signal from a speaker to a microphone of said cellular telephone; and transmitting said received acoustic signals by said cellular telephone.

Description

CELLULAR TRANSMISSION OF PHYSIOLOGIC DATA

FIELD OF THE INVENTION

The present invention is related to the field of tele-medicine and in particular to the transmission of physiologic signals data, such as ECG measurements using cellular telephones.

BACKGROUND OF THE INVENTION

Cardiac patients need to have their cardiac activity monitored periodically over a long time. As physical checkups at a doctor's office are time-consuming and expensive, remote monitoring is a solution that is gaining prominence. In a typical application, such as described in US patent number 5,467,773 and German Patent application number 19707681, the disclosures of which are incorporated herein by reference, ECG signals are sensed using electrodes, encoded and then transmitted over a telephone (or cellular) line. Both digital and analog encoding schemes are known.

A problem with digital cellular telephones, which is not addressed in the above patents is that digital systems, for example GSM, and to some extent analog systems, use audio compression algorithms which can completely distort the transmitted signal, if an analog signal is used.

SUMMARY OF THE INVENTION An object of some preferred embodiments of the invention is to provide a viable method of transmitting ECG and other real-time biological sensing data over cellular networks.

An aspect of some preferred embodiments of the invention relates to encoding ECG data using audio frequencies that are not overly distorted by speech compression algorithms. In the example of the GSM cellular telephone system, the inventors have determined that the range of 2900-3100 HZ is not significantly affected by speech processing in GSM cellular networks. Similar frequencies may be used in standard TDMA networks, for example as used by a cellular provider named Cellcom Ltd., in Israel at the time of filing of this application. In other network types, such as CDMA, for example as used by a cellular provider called Pelephone Ltd., in Israel, at the time of filing of this application, or in other standards of the above network types, a suitable frequency band may be a different band which is minimally compressed, for example for the reason that there are few speech related frequencies in it. This same frequency bandwidth may also be used to transmit analog encoded commands to the sensor. Alternatively, such commands are transmitted to the telephone itself, the commands to be carried out using its display and audio capabilities. An aspect of some preferred embodiments of the invention relates to integrating a biological sensor, such as an ECG sensor, into a removable part of a cellular telephone, so that modification of the telephone itself is not required. In a preferred embodiment of the invention, the sensor is integrated into a battery for the telephone. Alternatively or additionally, the sensor is attached onto the telephone. Optionally, the sensor can be removed from the telephone and attached to a standard telephone handset, for example if the cellular telephone is damaged or if service is unavailable.

An aspect of some preferred embodiments of the invention relates to a method of communication between a cellular telephone and a biological sensor. In a preferred embodiment of the invention, the sensor generates an acoustic signal that is indicative of the sensed variable and this signal is transmitted, by air, over a non-trivial distance, such as 1 cm or more, for example 2, 3 or more cm, to a microphone of the cellular telephone.

There is thus provided in accordance with a preferred embodiment of the invention, a method of transmitting physiologic signals data using a speech channel of a cellular telephone, comprising: selecting a frequency band which is not affected by speech compression of a transmission protocol of said speech channel; generating an acoustic signal in said frequency band, which signal encodes said physiologic signals data; transmitting said acoustic signal from a speaker to a microphone of said cellular telephone; and transmitting said received acoustic signals by said cellular telephone. Preferably, said frequency band is between 2900 and 3100 Hz. Alternatively or additionally, said transmission protocol is a GSM protocol. Alternatively, said transmission protocol is a TDMA protocol. In a preferred embodiment of the invention, the method comprises transmitting a response signal, from a remote location to said cellular telephone; and sounding a sound responsive to said response signal by a speaker of said cellular telephone. Preferably, said response signal is transmitted using said speech channel.

In a preferred embodiment of the invention, said physiologic signals data is encoded using an FM encoding protocol. Alternatively or additionally, said physiologic signals data is encoded using an AM encoding protocol. Alternatively or additionally, said physiologic signals data is transmitted in real-time, as it is acquired. Alternatively, said physiologic signals data is transmitted from a memory, at a delay after it is acquired. In a preferred embodiment of the invention, the method comprises acquiring said physiologic signals data from a signal generated between two fingers, of different hands.

In a preferred embodiment of the invention, said physiologic signals data comprises ECG data. There is also provided in accordance with a preferred embodiment of the invention, apparatus for acquisition and transmission of ECG data, comprising: a casing adapted to be mounted on a cellular telephone; at least one electrode for acquiring ECG data; and a speaker for sounding said data to a microphone of said cellular telephone. Preferably, the apparatus comprises a battery powering both said apparatus and said cellular telephone.

Alternatively, the apparatus comprises a separate battery for powering said apparatus.

Preferably, said separate battery is rechargeable and comprising a charging circuit for charging said separate battery from a power circuit of said cellular telephone.

In a preferred embodiment of the invention, said at least one electrode comprises at least two electrodes. Alternatively or additionally, the apparatus comprises an isolator for isolating said at least one electrode from a power source of said apparatus. Alternatively, at least one electrode is not electrically isolated from a power source of said apparatus.

In a preferred embodiment of the invention, said at least one electrode is positioned such that it is blocked from access by a charger designed for a said cellular telephone, when said cellular telephone is inserted in said charger.

In a preferred embodiment of the invention, the apparatus comprises a modulation circuit which modulates said ECG data for sounding by said speaker. Preferably, said modulation circuit generates a signal between 2900 and 3100 Hz. Alternatively or additionally, said modulation circuit is an FM modulator. Alternatively or additionally, said modulation circuit is an AM modulator.

In a preferred embodiment of the invention, the apparatus comprises a casing for said apparatus. Preferably, said at least one electrode is flush with said casing. Alternatively or additionally, said casing is a same size as a standard battery for said cellular telephone. Alternatively, said casing is adapted to be mounted on said cellular telephone. In a preferred embodiment of the invention, the apparatus comprises a timing circuit which operates said apparatus for a fixed period of time after activation. Alternatively or additionally, the apparatus comprises a control for activating said apparatus. Alternatively or additionally, the apparatus comprises a detection circuit for detecting a data producing contact with said electrodes and for activating said apparatus in response to said detected contact. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood from the following detailed description of the preferred embodiments of the invention and from the attached drawings, in which: Fig. 1 is a side view of a cellular ECG monitor, in accordance with a preferred embodiment of the invention;

Fig. 2 is a schematic block diagram of a system including a cellular ECG monitor, in accordance with a preferred embodiment of the invention;

Figs. 3A-3C illustrate various isolation methods for cellular ECG monitors, in accordance with preferred embodiments of the invention;

Fig. 4A is a schematic block diagram of a cellular ECG monitor, in accordance with a preferred embodiment of the invention;

Figs. 4B-4F show a circuit diagram for the ECG monitor of Fig. 4A; and

Fig. 4G is a graph showing a frequency response of the circuit of Fig. 4B. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 is a side view of a cellular ECG monitor 100, in accordance with a preferred embodiment of the invention. Monitor 100 is integrated with a cellular telephone 102, which typically comprises a body, an antenna, a screen, a keypad and a microphone 112. A battery

104 is usually also coupled to the cellular telephone. In a preferred embodiment of the invention, monitor 100 comprises at least one and preferably tow or more electrodes 106 that detect ECG signals from a patient when the patient touches them. Circuitry (not shown) converts the ECG signals into audio-frequency signals, which are converted to sound waves by a speaker 110. The sounds from speaker 110 are detected by microphone 112 and transmitted to a remote location. In a preferred embodiment of the invention, the sounds are transmitted by the telephone if they were speech sounds and not as digital or analog data packets.

In a preferred embodiment of the invention, the ECG signals are encoded using FM encoding. However, other non-AM encoding methods may be used as well, for example,

QPSK. Alternatively, AM type encoding methods may be used, however these may be less suitable in some situations due to interference from the body. However, in some uses of the monitor, the body is far enough away from the monitor that AM disturbances may not pose a problem.

In a preferred embodiment of the invention, the signals are used to modulated a carrier wave within a band between 2900 and 3100 Hz. In some cases a more limited bandwidth may be desired, such as between 2950 and 3050. Alternatively, a higher frequency band may be available, such as between 3000 and 3200 or 3300 Hz. Preferably, telephone 102 is a GSM telephone, in which a digital speech encoding method is used to reduce bandwidth requirements for speech. The inventors have determined that the above frequencies are less affected by signal processing of the speech sounds in GSM and in TDMA networks. Additionally to transmitting higher frequencies, monitor 100 may also generate a more direct acoustic encoding of the ECG signals, or at least the heart-beat itself, to reassure a patient that ECG signals are being detected and/or that the heart has a normal ECG signal.

In one embodiment of the invention, ECG monitor 100 is activated using a control 108 (shown for clarity protruding from the back of the device, but could also be flush and/or at the side of the device). Alternatively or additionally, electrodes 106 are pressure-activated, such that a pressure against them activates the ECG monitoring function. Alternatively or additionally, they may be electrically activated by the body electrical properties, for example its static charge or its effect on the capacitance of the electrodes or the presence of an ECG signal. In a preferred embodiment of the invention, a mechanical guard is provided on the electrodes and/or control 108 to avoid inadvertent operation of monitor 100.

In a preferred activation method, two electrodes 106 are used, and a patient touches each electrode with a finger from a different hand. Alternatively or additionally, monitor 100 is pressed against the flesh, for example on the chest or the abdomen. Possibly, monitor 106 may be held at different orientations on the body to simulate different placements of electrodes. Alternatively or additionally, a patient may use other electrode types than contact electrodes, for example adhesion type of vacuum type electrodes, that are then coupled to electrodes 106 or connected into one or more jacks or other connectors on monitor 100 (not shown). In one example, a standard vacuum electrode can have a metal pad attached to it, remote from the electrode which contacts the body, using a lead. One side of the pad is electrically isolated and the other is conductive. A patient presses the conducting side of the pad against an electrode 106 using the isolated side of the pad, in order to couple signals from the vacuum electrode to electrode 106.

In a preferred embodiment of the invention, once monitor 100 is activated it automatically works for a certain period, without user intervention. This period may be preset, for example half a minute or a minute. Alternatively or additionally, this period is determined based on the quality of the detected ECG signal. Alternatively or additionally, this period is modified responsive to a rudimentary analysis and detection of abnormalities in the ECG signal. Alternatively or additionally, this period is determined based on a schedule, for example one minute once a week or half a minute every day. Generally, in some preferred embodiments of the invention, the duration of measurement is not dependent on what is received at a remote location, rather, the ECG signal is transmitted using an open loop transmitting method.

In some preferred embodiments of the invention, battery 104 is enclosed in a standard size battery shell in which both a (smaller) battery and monitor 100 are contained. Alternatively, battery 104 is enclosed in a larger than usual shell, to accommodate at least part of the volume of monitor 104. Alternatively, monitor 100 is attached to the outside of the battery. Alternatively, monitor 100 is attached as a separate unit, sandwiched, between battery 104 and cellular telephone 102. Alternatively, in a less preferred embodiment of the invention, monitor 100 is a stand alone device which is placed in proximity to the cellular telephone during transmission.

In a preferred embodiment of the invention, speaker 110 is oriented so that sounds from it will reach microphone 112. Preferably, a suitable cellular telephone model is selected so that speaker 110 is flush with the battery 104. Alternatively, speaker 110 protrudes, for example to provide a better angle to the microphone. Alternatively or additionally, speaker 110 includes a sound-guide tube (not shown) which can be aimed at the microphone. Possibly, the tube is flexible so that it can be attached to a flip-opening mouthpiece of some known types of cellular telephone. Alternatively or additionally, sound travels using solid conduction through telephone 102 between speaker 110 and microphone 112. Fig. 2 is a schematic block diagram of a system 200 including cellular ECG monitor

100 and a receiving station 206, in accordance with a preferred embodiment of the invention. In the exemplary system shown, a monitor 100 measures an ECG signal and transmits it using a cellular telephone 102 to a receiving station 206. Typically, receiving station 206 comprises a telephone receiver 202 and, optionally, a computer 204. In some cases, telephone receiver 202 is degenerate and comprises a telephone sampling card which is inserted in a personal computer and which samples analog signals off a telephone line and provides them to a data bus of the computer. Receiving station 206 may be a central station, for example for a central monitoring unit. Alternatively, receiving station 206 may be located at a doctor's office. Possibly, data at one or more receiving stations is forwarded to a second remote location (not shown).

A computer 204 (or other suitable circuitry) is useful for automating the monitoring process. In one example, the computer can initiate a reminder call to a patient to monitor his ECG, possibly waiting on-line for the ECG data. Alternatively or additionally, computer 204 or a remote computer can analyze the ECG data, possibly in real-time, to alert the patient for a need to see a physician or possibly order immediate help. Alternatively or additionally, computer 204 can provide automatic feedback to the patient that the measurements are arriving at a high enough quality. Possibly, computer 204 operates an INR (interactive voice response) menu system, to guide the activity of the patient. Alternatively or additionally, a test control (not shown) may be supplied in conjunction with monitor 100, to transmit a test signal to computer 204. Possibly, this and/or other controls are voice operated. Possibly, voice analysis is carried out at computer 204 or at a central office of the telephone, rather than by monitor 100.

It should be noted that since a regular speech channel is preferably used, there is available a return path for messages and alerts from the receiving station to the patient, on the same channel. Possibly, if a problem is detected, a loud feedback to the patient may be generated, to alert bystanders. Alternatively, a call-back function may be utilized by computer 204. Alternatively or additionally, in some cellular phones, a data lead connects the battery and the cellular phone. This contact, or other available contacts may be used for the transmission of data.

Alternatively or additionally to real-time measurement and transmission of ECG, a patient may record ECG measurements, using an optional memory 120, and transmit them later. This feature is useful, for example, if the patient feels a special condition that may pass by the time a cellular connection is completed. Alternatively or additionally, a delay may be provided between the patient activating monitor 100 and the actual transmission of ECG signals, to allow time for electrode placement and/or making a cellular connection.

Optionally, a distressed patient can be located using a GPS locator coupled to the cellular telephone or the battery or using cellular localization techniques known in the art.

Alternatively or additionally, a composite control may be attached to the cellular telephone such that pressing it activates both the cellular telephone and monitor 102, for example to simultaneously call for help and transmit up-to-date ECG data.

In a preferred embodiment of the invention, monitor 100 transmits patient identification information, for example at the beginning, middle or end of the call. The patient ID or other important information may be transmitted using analog encoding and/or using a DTMF or DTMF-like encoding. The ID may be programmed, for example using dip-switches in monitor 100. Alternatively, a caller ID function is used to associate a particular cellular telephone with a particular patient.

Figs. 3A-3C illustrate various isolation methods for cellular ECG monitors, in accordance with preferred embodiments of the invention. Although isolation may not be strictly required, as monitor 100 is not usually coupled to the body while connected to a line voltage, such isolation may be desirable for increasing the safety level of use.

Fig. 3 A illustrates a first configuration 300, in which a monitor 100 uses a separate battery 302 from a battery 104 used by a cellular telephone 102. A charger 304 connects only to battery 104. Battery 302 may be a non-rechargeable battery, possibly containing enough energy for a fixed number of uses, for example for a year's worth of monitoring. Possibly, a use counter is provided in this or other embodiments to limit the number of times the device is used, for example, to ensure payment of fees or to ensure periodic calibration and/or other maintenance of monitor 100. Alternatively or additionally, a clock function may be provided to monitor the term of use of monitor 100.

Alternatively, a separate charger may be provided for battery 302. Preferably, when battery 302 is being charged, access to electrodes 106 is mechanically restricted, for example by the design of the charger.

Fig. 3B illustrates a configuration 310, in which a single battery 104 is shared by both monitor 100 and telephone 102, and an isolator 312, such as an optical, acoustic, RF or magnetic coupler is used to isolate the electrodes from the charger. Alternatively, nonconducting electrodes are used. Alternatively, isolation may be provided on the connection between monitor 100 and battery 104.

Fig. 3C illustrates a configuration 320, in which a battery 302 of monitor 100 is recharged by battery 104 (or from another source) using non-contact energy transmission means 322, for example RF coupling.

Fig. 4A is a schematic block diagram of a cellular ECG monitor, in accordance with a preferred embodiment of the invention. Figs. 4B-4F show a circuit diagram for the ECG monitor of Fig. 4A. Each of figures 4B-4F shows a part of the circuit, which is shown in a plurality of figures for convenience of presentation. Outgoing arrowheads labeled with a letter on the right side of a figure show connection points with ingoing arrowheads labeled with the same letters on the left side of a following figure. Table I is a parts list of the components of the circuit shown in Figs. 4B-4F.

TABLE I

ECG signals are such that, even without processing, they have a generally narrow bandwidth. An advantage of ECG signals is that this bandwidth is generally narrower than the available transmission bandwidth. Optionally, the signals may be filtered prior to being transmitted, to reduce noise and/or further limit the bandwidth. Fig. 4G is a graph showing a frequency response of the circuit of Fig. 4B, in accordance with a preferred embodiment of the invention. The above description has focused on ECG signals, however, a similar device may also be used to detect and transmit other types of physiologic signals, for example, pulse oximetery signals, EEG signals, blood pressure measurements and respiration. Some of these signals may also be measured using a contact electrode on monitor 100, others, such as EEG, may require a separate electrode. Such a separate electrode is preferably stored in a compartment of monitor 100. Alternatively or additionally, monitor 100 may be used to monitor the operation of an implanted device, such as a pacemaker. In one example, a pacemaker in a safe mode may generate an extra voltage spike every beat. Similar extra spikes are known in the art. This spike and/or other characteristics of the pacing signals can be detected as being overlaid on the ECG. Alternatively or additionally, an implanted device, such as an insulin pump, may generate an electric field, possibly pulsed or otherwise modulated, to be sensed by electrodes 106 or by field detectors, such as coil detectors.

The present invention has been described in terms of non-limiting embodiments thereof. It should be understood that features described with respect to one embodiment may be used with other embodiments and that not all embodiments of the invention have all of the features shown in a particular figure. In particular, the scope of the claimed invention is not limited by the described embodiments but by the following claims. In some embodiments only methods have been described, the scope of some embodiments of the invention is intended to encompass also hardware and/or software implementations of these methods. Section titles, where they appear, are not to be construed as limiting subject matter described therein, rather section titles are meant only as an aid in reading the specification. When used in the following claims, the terms "comprises", "comprising", "includes", "including" or the like mean "including but not limited to".

Claims

1. A method of transmitting physiologic signals data using a speech channel of a cellular telephone, comprising: selecting a frequency band which is not affected by speech compression of a transmission protocol of said speech channel; generating an acoustic signal in said frequency band, which signal encodes said physiologic signals data; transmitting said acoustic signal from a speaker to a microphone of said cellular telephone; and transmitting said received acoustic signals by said cellular telephone.

2. A method according to claim 1, wherein said frequency band is between 2900 and 3100 Hz.

3. A method according to claim 1 claim 2, wherein said transmission protocol is a GSM protocol.

4. A method according to claim 1 claim 2, wherein said transmission protocol is a TDMA protocol.

5. A method according to any of claims 1-4, comprising transmitting a response signal, from a remote location to said cellular telephone; and sounding a sound responsive to said response signal by a speaker of said cellular telephone.

6. A method according to claim 5, wherein said response signal is transmitted using said speech channel.

7. A method according to any of claims 1-6, wherein said physiologic signals data is encoded using an FM encoding protocol.

8. A method according to any of claims 1-6, wherein said physiologic signals data is encoded using an AM encoding protocol.

9. A method according to any of claims 1-8, wherein said physiologic signals data is transmitted in real-time, as it is acquired.

10. A method according to any of claims 1-8, wherein said physiologic signals data is transmitted from a memory, at a delay after it is acquired.

11. A method according to any of claims 1-10, comprising acquiring said physiologic signals data from a signal generated between two fingers, of different hands.

12. A method according to any of claims 1-11, wherein said physiologic signals data comprises ECG data.

13. Apparatus for acquisition and transmission of ECG data, comprising: a casing adapted to be mounted on a cellular telephone; at least one electrode for acquiring ECG data; and a speaker for sounding said data to a microphone of said cellular telephone.

14. Apparatus according to claim 13, comprising a battery powering both said apparatus and said cellular telephone.

15. Apparatus according to claim 13, comprising a separate battery for powering said apparatus.

16. Apparatus according to claim 15, wherein said separate battery is rechargeable and comprising a charging circuit for charging said separate battery from a power circuit of said cellular telephone.

17. Apparatus according to any of claims 13-16, wherein said at least one electrode comprises at least two electrodes.

18. Apparatus according to any of claims 13-17, comprising an isolator for isolating said at least one electrode from a power source of said apparatus.

19. Apparatus according to any of claims 13-17, wherein said at least one electrode is not electrically isolated from a power source of said apparatus.

20. Apparatus according to any of claims 13-17, wherein said at least one electrode is positioned such that it is blocked from access by a charger designed for a said cellular telephone, when said cellular telephone is inserted in said charger.

21. Apparatus according to any of claims 13-20, comprising a modulation circuit which modulates said ECG data for sounding by said speaker.

22. Apparatus according to claim 21, wherein said modulation circuit generates a signal between 2900 and 3100 Hz.

23. Apparatus according to claim 21, wherein said modulation circuit is an FM modulator.

24. Apparatus according to claim 21, wherein said modulation circuit is an AM modulator.

25. Apparatus according to any of claims 13-24, comprising a casing for said apparatus.

26. Apparatus according to claim 25, wherein said at least one electrode is flush with said casing.

27. Apparatus according to claim 25, wherein said casing is a same size as a standard battery for said cellular telephone.

28. Apparatus according to claim 25, wherein said casing is adapted to be mounted on said cellular telephone.

29. Apparatus according to any of claims 13-28, comprising a timing circuit which operates said apparatus for a fixed period of time after activation.

30. Apparatus according to any of claims 13-29, comprising a control for activating said apparatus.

31. Apparatus according to any of claims 13-29, comprising a detection circuit for detecting a data producing contact with said at least one electrode and for activating said apparatus in response to said detected contact.