WO2001064103A1

WO2001064103A1 - Bed mattress monitor

Info

Publication number: WO2001064103A1
Application number: PCT/AU2001/000219
Authority: WO
Inventors: Colin Edward Sullivan
Original assignee: Health Smarts Group Pty Ltd
Priority date: 2000-03-02
Filing date: 2001-03-02
Publication date: 2001-09-07
Also published as: AUPQ596800A0

Abstract

This invention concerns a bed mattress equipped with sensors to monitor patients or invalids. The mattress is associated with a bed. A computerised control system is integrated with the bed and associated with the mattress to receive and process signals received from the mattress sensors, and it is able to transmit them for remote evaluation. The mattress, includes a series of transversely extending grooves in its upper surface, arranged in the area overlayed between the shoulder to the hip, and in which there are located displacement sensor assemblies. Also an array of wells are arranged in the area overlayed between the shoulder to the hip and at different locations across the mattress. In the wells are located acoustic sensor.

Description

BED MATTRESS MONITOR

Technical Field

This invention concerns a bed mattress equipped with sensors to monitor patients or invalids, The mattress is associated with a bed. A computerised control system is integrated with the bed and associated with the mattress to receive and process signals received from the mattress sensors, and it is able to transmit them for remote evaluation.

Background Art

Pressure sensitive mats for use on top of mattresses have been known for some time. These mats are used, for instance, to sense whether an infant lying on the mat is moving, or has stopped moving. If all movement, including breathing movement, stops for longer than a predetermined period of time, an alarm is activated.

More complicated arrangements have also been proposed, where sensors are installed inside a mattress. These sensors are intended to register body functions, such as respiration and heart beat. However, to date they have not been well developed or found to be effective,

Summary of the Invention

The invention, as currently envisaged, is a bed mattress of fire retardant foam, such as Dunlop foam EN80, including:

A series of transversely extending grooves in the upper surface of the mattress. The grooves are arranged in the area overlayed between the shoulder to the hip, and in the grooves there are located displacement sensor assemblies. These assemblies may be arranged to extend just above the upper surface of the mattress.

The is also an array of wells arranged in the area overlayed between the shoulder to the hip and at different locations across the mattress. In the wells there are located acoustic sensor assemblies. These assemblies may also be arranged to extend just above the upper surface of the mattress.

The displacement sensor assemblies may include the sensors themselves embedded in strips of the mattress material, and the strips may be cushioned in the grooves by pads. The sensors may be PNDF coaxial cable comprising a central conductor surrounded by a PVDF strip and a braid outer conductor.

The grooves cut into the mattress may be 'V-shaped in section, as may the strips, and two softer foam pads may be provided extending along either side of the contacting surfaces. The upper surface of the strips may extend above the level of the surface of the mattress, and the sensor may extend just below the upper face of the strip.

The acoustic sensor assemblies may comprise a housing with a diaphragm of PNDF material extending across the top, and a cushion of moulded high rise latex foam material or silicone dome located on top of the diaphragm. The PVDF membrane may be housed in an aluminium casing which forms the shield and live connection of the sensor.

The grooves may extend horizontally and directly across the mattress, and the wells may be arranged between the grooves. The mattress may be mounted on a bed, and a computerised control system may be integrated with the bed and associated with the mattress to receive and process signals received from the mattress sensors. It is able to transmit them for remote evaluation.

A console may be provided to receive the signals produced by the sensors and process them for display or interpretation. A liquid crystal touch screen incorporated at the end of the bed is preferred. The data may be played forward or backward and different data may be synchronised for simultaneous display.

The signals that may be extracted include signals representing: body movement, heart movement, heart sounds, breathing movement, breathing sounds in the frequency range of 50-1000F£z. Such a sensor may amount to an electronic stethoscope. Additional sensors may be provided to capture readings of weight, temperature and muscle movement, as well as gastric and gut sounds, reflux and muscle spasm sound etc, generated by the patient. Audio and video surveillance may also be provided. A recording may be made. Flags may be used to identify selected episodes in the recording. A time loop and trigger may enable selected episodes only to be recorded.

Remote monitoring may be provided.

Signals may be transmitted over a telephone network for the remote monitoring.

The equipment may be used to monitor a patients basic vital signs, and to conduct a basic physical examination. Optional extra monitoring may also be provided.

Brief Description of the Drawings

An example of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is an elevation of a mattress including sensor assemblies arranged in it;

Figure 2 is a plan view of the mattress of Figure 1;

Figure 3 is a detail showing the mounting of a displacement sensor in the mattress;

Figure 4 is a detail showing the mounting of an acoustic sensor in the mattress;

Figure 5 is a block diagram of the signal processing system.

Best Modes of the Invention

Referring first to Figures 1 and 2, mattress 1 comprises a foam mattress 2 having formations in its upper surface to receive sensor assemblies between the shoulder and the hip areas.

Three triangular grooves, indicated at 3 extend transversely across the mattress to receive displacement sensor assemblies 4. Cylindrical cutouts 5 in the surface of mattress 2 receive acoustic sensors 6. Referring now to Figure 3, the displacement sensor assemblies 4 can be seen to comprise a coaxial sensor 7 embedded in a strip 8 of the same material as the mattress. The strip 8 has a triangular wedge-shaped section, and is mounted into a groove in the upper surface of the mattress. The strip 8 is cushioned in the triangular groove 3 by two mats 9 and 10 of softer foam material. In this way the longitudinally extending sensor 7 is held in good contact with a body lying on the bed no matter where the body is positioned along the length of the sensor.

The sensor 7 is a coax having a central conductor 11 and an outer braid conductor 12 separated by PVDF material. The sensor 7 generates an electrical signal related to the amount of distortion it experiences; relative to its relaxed position, where it is straight and horizontal. The sensor is not sensitive to where the distortion takes place along its length.

Referring now to Figure 4, the acoustic sensor assemblies 6 are seen to be mounted in cylindrical recesses 5 cut into the upper surface of the mattress. The sensor comprises a cylindrical body 14 having a diaphragm of PVDF material 15 across it's top to generate electrical signals in response to acoustic and pressure signals received, by the piezo electric effect. A thin layer 16 of closed cell latex material is placed over the top of the sensor and stands slightly proud of the upper surface of mattress 2 to make contact with a body lying on the bed. An array of the acoustic sensors are arranged on the bed so that one is in proximity to the body no matter where it rolls from side to side.

The cylindrical body, namely aluminium casing, of sensor 6 extends at the top to shield the diaphragm, and an aluminium ring 17 locks it in place and provides a live connector. Signals received from the sensors are taken and analysed in order to generate signals which represent body movement, heart movement, heart sounds, breathing movement, breathing sounds, in the frequency range of 50-1000Hz, and abnormal breathing sounds such as crepitations which identify fluid in the lungs and rhonchi or wheezing which might signify asthma.

Additional sensors may be provided to measure temperature, muscle movement and other sounds generated by the patient such as vocalisation or gut sounds. Video surveillance may also be provided. Manual measurements may be made by a nurse to confirm the readings of the sensors or for calibration purposes.

Signal traces representing these signals are extracted from the gross signals received by the sensors using appropriate filtering and processing. These signals may be displayed for review, for instance in a console 20 mounted at the foot of the bed. The signals, before or after processing, may be recorded, and they may also be transmitted, for instance over a telephone network, to a remote location for review. The signals may be logged against the particular patient and stored in their records. To assist in this there may be a sensor associated with the bed and the console to detect the identity of the patient. This may achieved by reading a tag that the patient wears, such as a bar coded bracelet or an electronic identity device.

A flag algorithm may be provided to respond to particular signals, or combinations of signals, in order to mark time epochs where events of interest may be taking place. For instance, the onset of crepitations can be used to flag the occurrence of fluid in the lung airways and so indicate insipient heart failure or lung infection. The algorithm may flag an epoch extending over a period of time beginning before the crepitations commenced, and extending into the future following the time of onset. This epoch may, as a result be easily identified from a recording taken, say, overnight. Alternatively, the flag may act as a trigger to cause only the epoch to be recorded. In another example a digital camera may trigger the capture of physiological events such as coughing fits, spasms or strokes during the event plus fifteen seconds before and after the event has concluded.

Referring now to Figure 5 the signals from the sensors, indicated generally at 30, are subject to preamplification in preamplifiers 31, filtering in filters 32, analogue to digital conversion in converters 33 and computer signal processing in computer 34. The computer processing will develop algorithms to identify heart rate, beat to beat, breathing rate, and breathing sounds as well as other signals of interest. Traces are extracted from the signals and are displayed on screen 35, or they may be transmitted over a telephone network indicated generally at 36 for remote review at remote terminals 37.

Additional features of the system may involve a call alarm for nurse's help, a telephone facility or a TV/Nideo conferencing facility. Oximetry, EEG, ECG and blood glucose and other inputs may also be provided. A power supply together with circuit breakers which would trip in the event of current leakage may also be provided.

The mattress may have an integrated computer recording system to enable the continuous recordings from the sensors. In addition, this integrated computer system now can function as a portal or interface to a digital network for local observation and further provides an integrated system which can take externally recorded signals or data. Thus the system has an external input module into which an array of measures can be recorded. These include blood pressure, for example that recorded with an automatic sphygmomanometer, spirometry or peak flow measures, electrocardiogram, and other biological signals, and pathology measures such as blood glucose. Some of these measures will be measured with a device operated by the patient or nurse, such as a finger prick blood sample taken with hand held biosensors, the result of which is transmitted to the bed integrated computer hub, either directly with cable connections or by local telemetry. The provision of a touch screen as part of the bed, allows for the direct entry of data, such as a temperature measure, into the system.

The integrated computer recording system also can act as the hub for recording of all telemetered functions. For example, many people have ambulatory recording of electrocardiogram (the "Holter" monitor), by means of a portable recorder attached to the patient, for instance on a waist belt like a mobile phone. The bed system is designed to act as the receiving station for any telemetered (radio transmitted) signals. Thus, instead of the patient requiring a full recorder for ambulatory electrocardiogram, they can wear a miniature sensor with transmitter with the receiver being part of the bed, and the data being recorded in real time in the integrated bed computer. This has the particular advantage of allowing the operation of detection algorithms, which may identify dangerous heart rate change, and then call back to a nursing station, or remote carer.

The mattress may also incorporate therapeutic functionality such as air pockets that are automatically inflated and deflated to move the patient and prevent bed sores. This functionality may be initiated in response to algorithms driven by signals from the sensors. This may operate according to an automatic regime, or respond to signals from the sensors.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A bed mattress, including: a series of transversely extending grooves in the upper surface of the mattress, arranged in the area overlayed between the shoulder to the hip, and in which there are located displacement sensor assemblies; and an array of wells arranged in the area overlayed between the shoulder to the hip and at different locations across the mattress, and in which there are located acoustic sensor assemblies.

2. A bed mattress according to claim 1, where the mattress is constructed of fire retardant foam.

3. A bed mattress according to claim 1, where the displacement sensor assemblies include sensors embedded in strips of the mattress material, and the strips are cushioned in the grooves by pads.

4. A bed mattress according to claim 3, where the displacement sensors are PVDF coaxial cables comprising a central conductor surrounded by a

PVDF strip and a braid outer conductor.

5. A bed mattress according to claim 3, where the grooves are 'V'-shaped in section, as are the strips, and two softer foam pads extend along either side of the contacting surfaces of the grooves and strips.

6. A bed mattress according to claim 1, where the acoustic sensor assemblies comprise a housing with a diaphragm of PVDF material extending across the top, and a cushion located on top of the diaphragm.

7. A bed mattress according to claim 6, where the cushion is of moulded high rise latex foam material or silicone dome.

8. A bed mattress according to claim 6, where the PVDF membrane is housed in an aluminium casing which forms the shield and live connection of the sensor.

9. A bed mattress according to claim 1, where the grooves extend horizontally across the mattress, and the wells are arranged between the grooves.

10. A bed mattress according to claim 1, where the mattress is mounted on a bed. and a computerised control system is integrated with the bed and associated with the mattress to receive and process signals received from the mattress sensors.

11. A bed mattress according to claim 10, where the computerised control system is able to transmit the signals for remote evaluation.

12. A bed mattress according to claim 10, where a console is provided to receive the signals produced by the sensors and process them for display or interpretation.

13. A bed mattress according to claim 12, where the console includes a liquid crystal touch screen at the end of the bed.

14. A bed mattress according to claim 10, where the computerised control system is able to extract signals representing: body movement, heart movement, heart sounds, breathing movement, breathing sounds in the frequency range of 50-1000Hz and crepitations.

15. A bed mattress according to claim 14, where additional sensors are provided to capture readings of weight, temperature and muscle movement, as well as gastric and gut sounds, reflux and muscle spasm sound generated by the patient.

16. A bed mattress according to claim 10, where audio and video surveillance are also provided.

17. A bed mattress according to claim 10, where records of the signals are made, flags are used to identify selected episodes in the recording, and a time loop and trigger enable selected episodes only to be recorded.

18. A bed mattress according to claim 1, incorporating sensors to receive information concerning the identity of a person lying on, or being adjacent, the bed.

19. A bed mattress according to claim 1, incorporating a portal interface.

20. A bed mattress according to claim 1, incorporating therapeutic functionality.

21. A bed mattress according to claim 20, where the therapeutic functionality is triggered by signals received from the sensors.