US20080077020A1

US20080077020A1 - Method and apparatus for monitoring vital signs remotely

Info

Publication number: US20080077020A1
Application number: US11/849,051
Authority: US
Inventors: Steven Jay Young; William McKinnon Gillon; Richard Vincent Rifredi; William Todd Krein
Original assignee: BAM Labs Inc
Current assignee: Sleep Number Corp
Priority date: 2006-09-22
Filing date: 2007-08-31
Publication date: 2008-03-27
Also published as: US20230063373A1; US11439345B2; US20170065220A1; US20190069840A1

Abstract

A method and apparatus for monitoring vital signs, such as cardiopulmonary activity, using a ballistograph are provided. The method and apparatus may be used to monitor an infant sleeping in a crib, a patient in a hospital, a person with a chronic disease at home or in professional care, or a person in an elder-care setting.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Application No. 60/846,642, filed Sep. 22, 2006, which is hereby incorporated in its entirety by reference.

TECHNICAL FIELD

The present method and apparatus relate to monitoring vital signs, such as the presence of a heartbeat and breathing, in an human or animal, e.g., an infant sleeping in a crib, a patient in a hospital setting, a person with a chronic disease, a person in an elder-care setting, or an animal at home or in the care of a professional.

BACKGROUND

There are a variety of settings in which monitoring one or more vital signs of an individual can be important. For example, sleeping infants may be monitored for respiration or heartbeat, to alert parents or guardians to changes in the infant's heart of breathing status, caused for example, by sudden infant death syndrome (SIDS) or accidental suffocation. In a hospital setting, such as an emergency room (ER) waiting area, ambulance, or where an individual has been hospitalized with a cardiac condition, it may be important to monitor the individual's heart rate, both to provide an alert for a catastrophic systems failure or to monitor changes in heart rate status, e.g., in response to certain medications. Elder care patients who are at risk for cardiovascular failure or decline may also need vital-signs monitoring, to alert an attendant to dramatic changes in health status or the need for drug intervention. Typically, these are all settings in which an individual is lying or sitting at rest.
A number of devices designed for monitoring vital signs are known. In a hospital setting where a patient's heart rate and function are being monitored, it is usual to record a continuous electrocardiogram (EKG or ECG) of the patient. This is performed by attaching a number of electrodes to various points of the patient's chest and back region, to measure the rhythmic electrical activity of the heart. An EKG hookup tends to be uncomfortable and confining over extended periods, and requires a trained medical professional to apply the electrodes properly and to operate the device. For example, during sleep, the electrodes can come off the patient and cause a false alarm. The cost and inconvenience of EKG monitoring make it impractical for many health-monitoring settings, such as non critical hospital patients, infant or elder care monitoring.
A less intrusive means for measuring heart rate is a mechanical inertial device known as a ballistocardiograph, which is designed to record the volume of blood passing through the heart, at any period in time, based on the body's recoil as blood is ejected from the heart ventricles with each heartbeat. Such devices, as exemplified by U.S. Pat. No. 4,679,569, tend to have a rigid, mechanical plate structure and a complicated mechanism for measuring changes in plate motion.
There exists a need for a monitoring apparatus that has a simplified, relatively inexpensive construction, can be used comfortably by an individual on a mattress or chair, does not require any patient hookup, can be used easily by an untrained person, and provides accurate heart and respiration-rate information to a monitoring site or person.

SUMMARY

The invention includes, in one aspect, an apparatus for monitoring heart and respiration rates of a human subject at rest, comprising, in operative condition,
(a) a sensing unit having (i) a fluid or gas-filled pad adapted to be placed on a bed, crib, or chair support, for cushioning at least an upper body portion of a subject lying on or resting against the support, mattress or cushion, and (ii) a pressure sensor in fluid communication with gas or fluid in said unit, for generating electrical signals in response to pressure variations within the gas or fluid in the pad, and
(b) a monitoring unit operatively connected to said pressure sensor, for (i) receiving signals therefrom, (ii) generating from said signals, information about the heart and respiration rates of the subject, and (iii) relaying such information to a monitoring station or individual.
In some embodiments, the pad is a fluid-filled pad. In some embodiments, the pad is a gas-filled pad.
In some embodiments, the apparatus further includes a pressure-control unit comprising a pump in fluid or gas communication with the pad and a controller operatively connected to the pump for maintaining fluid or gas within the pad at a selected pressure or within a defined pressure range.
In some embodiments, the pad comprises a single fluid or gas-filled chamber, having a pressure sensor in fluid or gas communication therewith, for generating electrical signals in response to pressure changes within the chamber.
In other embodiments, the pad includes at least two independent, fluid or gas-filled chambers, each of which has a pressure sensor in fluid communication therewith, for generating electrical signals in response to pressure changes within the associated chamber.
In some embodiments, the apparatus further includes an ambient-null device comprising a fluid or gas-filled ambient pad, a weight carried on the ambient pad, for exerting pressure thereon, and an ambient pressure sensor in fluid or gas communication with fluid in the ambient pad, for generating electrical signals in response to pressure changes within the fluid or gas, in response to ambient motion in the vicinity of the subject, wherein said monitoring unit is operatively connected to said ambient pressure sensor, for (i) receiving signals therefrom, and (ii) processing the signals received from the first-mentioned and ambient pressure sensors, to filter such ambient motion from motion related to the subject's heart and respiration rates.
In some embodiments, the monitoring unit includes a processor operative to (i) generate heart-rate information of the subject, based on time-dependent signals having frequency components in the range from about 0.1 to about 10 Hz, and (ii) generate respiration rate information of the subject based on time-dependent signals having frequency components in the range less than about 1 Hz. In particular embodiments, the information generated by the signal processor further includes blood-pressure information.
In some embodiments, the pad includes upper and lower independent, fluid or gas-filled chambers, each of which has a pressure sensor in fluid communication therewith, for generating electrical signals in response to pressure changes within the associated chamber, and the information generated by the processor includes information about the orientation of the individual with respect to the pad, based on a characteristic ventral, dorsal or lateral signals produced by processing the two separate signals generated for the two chambers.
In some embodiments, the monitoring unit includes a remote monitor, and a transmitter for transmitting such heart and respiration rate information from the processor to the monitor.
In some embodiments, the pad further includes temperature sensor for measuring the temperature of the individual on the pad.
In another aspect, a sensor unit for use with a monitoring unit is provided, for monitoring heart and respiration rates of a human subject at rest, comprising, in operative condition,
(a) a fluid or gas-filled pad adapted to be placed on a bed, crib, or chair support, for cushioning at least an upper-body portion of a subject lying on or resting against the support, and
(b) a pressure sensor in fluid communication with fluid in said unit, for generating electrical signals in response to pressure variations within the fluid or gas, and adapted to be operatively connected to such a monitor.
In some embodiments, the pad includes as single fluid or gas-filled chamber having a pressure sensor in fluid of gas communication therewith, for generating electrical signals in response to pressure changes within the chamber.
In other embodiments, the pad includes at least two independent, fluid-filled chambers, each of which has a pressure sensor in fluid or gas communication therewith, for generating electrical signals in response to pressure changes within the associated chamber. In some embodiments, the pad is a fluid-filled pad. In some embodiments, the pad is a gas-filled pad.
In another aspect, a method for monitoring vital signs is provided, including heart and respiration rates, of a human subject lying on or resting against a bed, crib, or chair support, comprising
(a) placing between the subject and the support, a fluid or gas-filled pad positioned for cushioning at least an upper-body area of the subject,
(b) generating electrical signals in response to pressure variations within the fluid or gas by a pressure sensor in fluid communication with fluid or gas in said pad, and
(c) processing the electrical signals received from the pressure sensor to generate information about the heart and respiration rate of the subject.
In another aspect, an apparatus for remotely monitoring heart and respiration rates of a human subject lying on or resting against a bed, crib, or chair support is provided, comprising
(a) a pad adapted to the placed between the subject and the support, for cushioning at least an upper body portion of the individual,
(b) a sensor on said pad for generating motion-related signals caused by the subject's heartbeat and breathing,
(c) a processor operatively connected to said sensor, for (i) receiving time-dependent signals therefrom, and (ii) generating heart-rate information of the subject, based on received time-dependent signals in the range from about 0.1 to about 10 Hz, and respiration rate information of the subject, based on received timed-dependent signals in the range less than about 1 Hz,
(d) a remote monitor for use by an individual in monitoring said subject, and
(e) a transmitter for transmitting such subject information from the processor to the individual.
In some embodiments, the apparatus further includes an ambient-motion device for generating signals related to ambient motion in the vicinity of the subject, and said processor is operatively connected to said device, for processing the signals received from the device, to filter such ambient motion from motion related to the subject's heart and respiration rates.
In another aspect, an apparatus for monitoring vital signs is provided, including heart and respiration rates, of a human subject lying on or resting against a bed, crib, or chair support, comprising

- (a) a pad adapted to the placed between the subject and the support, for cushioning at least an upper body portion of the individual, said pad comprising
- (i) a pair of confronting plates, one adapted to be supported on the mattress, and the other adapted for contact with the chest area of the individual, said plates being spaced apart for relative lateral movement in an XY plane and relative vertical movement in the Z direction,

(iii) connecting the two plates, an L-shaped connector attached at opposite ends to the opposing plates and having a pair of laterally extending, orthogonally disposed arms, a strain gauge carried on each arm, in an XY plane, and a strain gauge carried on one of the arms, in a vertical plane, and
(b) a monitoring unit operative to transmit to a remote user, information about the heart rate of the individual, based on signals received from the pad's lateral-movement strain gauge devices, and about the respiration rate of the individual, based on signals received from the pad's vertical-movement strain gauge(s).
The apparatus of claim 20, wherein said two opposing plates are substantially rectangular, and connected by said L-shaped connectors in the region of each of the four corners of the two plates.
In some embodiments, the apparatus further includes a vertical-movement strain gauge connecting the two plates, for generating information about the weight applied by the individual on the pad.
In some embodiments, the monitoring unit includes a processor operative to (i) wherein said monitoring unit includes a signal processor operative to (i) generate heart-rate information of the subject, based on time-dependent signals received from each of the plural lateral-movement strain-gauge devices, and having frequency components in the range from about 0.1-10 Hz, and (ii) generate respiration rate information of the subject based on timed-dependent signals having frequency received from the at least one of the vertical-movement strain gauge(s), and having frequency components in the range less than about 1 Hz.
In some embodiments, the monitoring unit includes a remote monitor, and a transmitter for transmitting such heart rate and respiration rate information from the processor to the monitor.
In some embodiments, the pad further includes temperature sensor for measuring the temperature of the individual on the pad.
In some embodiments, the apparatus further includes a weighted strain gauge adapted for attachment to the bed or crib, independent of said pad, for detecting movement of the bed or crib, independent of movement within the pad, and the monitoring unit is operative to remove such independent movement from pad movement detected by the pad strain gauges.
In a related aspect, an apparatus for determining the presence of a subject is provided, comprising:
(a) a sensing unit having (i) a fluid or gas-filled pad adapted to be placed on a bed, crib, or chair support, for cushioning at least an upper body portion of a subject lying on or resting against the support, mattress or cushion, and (ii) a pressure sensor in fluid communication with fluid in said unit, for generating electrical signals in response to pressure variations within the fluid in the pad, and
(b) a monitoring unit operatively connected to said pressure sensor, for (i) receiving signals therefrom, (ii) generating from said signals, information about the presence of the subject and (iii) relaying such information to a monitoring station or individual.
In another related aspect, a sensor unit for use with a monitoring unit, for detecting the presence of a subject is provided, comprising:
(a) a fluid or gas-filled pad adapted to be placed on a bed, crib, or chair support, for cushioning at least an upper-body portion of a subject lying on or resting against the support, and
(b) a pressure sensor in fluid communication with fluid in said unit, for generating electrical signals in response to pressure variations within the fluid or gas, and adapted to be operatively connected to such a monitor.
A related method for detecting the presence of a subject on or in a bed, crib, or chair support is provided, comprising:
(a) placing on or in the bed, crib, or chair support a fluid or gas-filled pad positioned for cushioning at least an upper-body area of the subject,
(b) generating electrical signals in response to pressure variations within the fluid or gas by a pressure sensor in fluid communication with fluid or gas in said pad, and
(c) processing the electrical signals received from the pressure sensor to generate information about the presence of the subject.
In a related aspect, an apparatus for monitoring the presence of a subject lying on or resting against a bed, crib, or chair support is provided, comprising:
(a) a pad adapted to the placed between the subject and the support, for cushioning at least an upper body portion of the individual, said pad comprising
(i) a pair of confronting plates, one adapted to be supported on the mattress, and the other adapted for contact with the chest area of the individual, said plates being spaced apart for relative lateral movement in an XY plane and relative vertical movement in the Z direction,
(iii) connecting the two plates, an L-shaped connector attached at opposite ends to the opposing plates and having a pair of laterally extending, orthogonally disposed arms, a strain gauge carried on each arm, in an XY plane, and a strain gauge carried on one of the arms, in a vertical plane, and
(b) a monitoring unit operative to transmit to a remote user, information about the presence of the subject, based on signals received from the pad's strain gauge devices.
Apparatus for monitoring the presence of a subject, rather than health of a subject, may be connected to the internet and may further include any of the additional features described herein.
These and other aspects and embodiments of the present invention will become better apparent in view of the detailed description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic side or perspective view of a monitoring method and apparatus.

FIG. 2. is a diagram illustrating how an embodiment of the system works. A pad sensing unit detects heart and respiration from the infant subject. Optional temperature and audio sensors provide additional data. A digital signal processor (DSP) analyzes data from the mattress pad sensing unit and other data.

FIG. 3 is a diagram illustrating an embodiment of the system that utilized an air-filled mattress sensor connected to an air pump (i.e., a pressure-control unit) for maintaining pad pressure within a predefined range. Vibrations corresponding to heart and respiration functions are detected by a pressure sensor, communicated to a computer for analysis, and distributed via the internet.

FIG. 4A-4D shows exemplary configurations of air or fluid-filled pad sensors having a single chamber (A) or multiple chambers (B-D).

FIG. 5 is a diagram showing how an air or fluid-filled mattress sensor is used to generate health status data. Vibrations are detected by pressure sensors, and the data are filtered and compared by a microprocessor. An ambient vibration cancellation device is also depicted.

FIG. 6 is a schematic showing how data generated by multiple sensors are analyzed by a DSP and used to trigger events.

FIG. 7. shows an example of processed data generated from a pad sensor using a 6-month-old infant subject.

FIGS. 8A and 8B illustrate components of a two-plate mechanical sensor having orthogonally disposed strain gauges for monitoring heart and respiratory functions. 8A is a side view showing an infant subject. 8B is a top view showing the strain gauges connecting the two plates.

FIG. 9 is a schematic showing how data generated by a mechanical sensor are analyzed by a DSP and used to trigger events.

FIG. 10 is a schematic showing how a wireless transceiver receiving data from a mattress sensor communicates with a remote microcontroller for monitoring and responding to health status data.

DETAILED DESCRIPTION

I. Introduction

A method and apparatus are provided for monitoring the presence and health status of human and animal subjects/patients. The method and apparatus utilize a pad or plate sensor unit adapted to be placed in a bed, cushion mattress, infant crib, or the like for generating health status data corresponding to the subject's cardiac function and/or respiration (i.e. breathing). The pad or plate sensor may be a fluid or gas-filled device, an electromechanical device, an optical device, or a semi-conducting device, depending on the embodiment.
Data generated from the sensor unit may be combined with additional data (e.g., generated by one or more additional sensors), filtered, and relayed to a microprocessor for recording or analysis. Processed data may be used to trigger one or more events. In some examples, the event is to sound an alarm or alert medical professionals to deteriorating health status of a subject. The health status data that trigger an event, and the events that are triggered, may be pre-selected by a user depend on the particular application.
The method and apparatus are readily integrated with internet/web-based services, wireless telecommunications, advanced audio and video processing, instant messaging, digital and analog signal processing, medical record databases and patient records, and private and public health agencies, thereby linking a subject's health status to any number of services.
FIG. 1 shows an exemplary monitoring method and apparatus. The view illustrates an infant crib 6 with a sensor pad or plate sensor 1 adapted for use as a mattress. A wireless in home monitor 2 is provided, e.g., to allow a parent or guardian 7 to monitor data from the sensor 1 via a wireless phone or internet protocol link 3. The crib is further equipped with a camera 4 to transmit live or delayed video, e.g., to allow the determination of whether the infant, adult, or animal is on its back, front, or sides, by identifying features of the subject, and a panic button 5. A wired or wireless transceiver can also be equipped to communicate between the sensor and the camera, panic button and remote monitor. As shown in FIG. 2, the pad or plate sensor 1 detects heart 9 and respiration vibrations in from the infant subject 10 along with data from optional additional sensors (i.e., a microphone 7 and thermometer 8). These data are transmitted, by wire or wirelessly, to a digital signal processor (DSP) 11, which analyzes the data and triggers appropriate actions.
The method and apparatus are described in more detail, below.

II. Monitoring Apparatus

A feature of the present method and apparatus is a sensor unit adapted for placement on a bed, crib, chair, automotive or avionics seat, or similar rest surface for a human or animal. In some embodiments, the sensor is in the form of a mattress or mattress pad, upon which a subject will rest. In other embodiments, the sensor is in the form of a cushion or cushion pad, upon which a subject will sit or lean. In other embodiments, the sensor is in the form of plate upon which a subject will rest.
Both fluid/gas-filled sensors and electromechanical sensors may be used according to the present method and apparatus. Such sensors may be referred to as ballistocardiographs, monitor-enabled pads or mattress, vital signs sensors, or health status data sensors.
Embodiments of the pad or plate sensor are described, below.

A. FLUID/GAS-FILLED PAD EMBODIMENT

In some embodiments, the sensor uses a fluid or gas-filled pad upon which a subject will rest. The fluid/gas-filled pad may be connected to a suitable fluid/gas pump to maintain a desirable pressure and/or volume in the pad. The pad is further connected to an fluid/gas pressure sensor, which monitors the pressure changes in the pad in response to a subject's hear function or respiration. According to this embodiment, incident pressure waves caused by shifting body weight in response to cardiopulmonary activity induces a change in the measured pressure, which data are sampled and processed. This embodiment of the method and apparatus are illustrated in FIGS. 3-5.
As shown in FIG. 3, a custom air mattress 10 is operably connected to an air pump 21 for filing the pad sensor to a preselected pressure or volume and an air pressure sensor 31 for monitoring the pressure in the mattress 10. Ballistic motion of the subject infant 100 caused by cardiac function and breathing cause pressure variations in the pad sensor 10, which can be detected by the pressure sensor 31, which produces or alters electrical signals in response to pressure variations. A signal (i.e., data; typically electrical) from the pressure sensor 31 is received by a microprocessor 200 for analysis. The raw or processed signal/data may be sent to the internet 300 for distribution.
FIGS. 4A-D illustrate several embodiments of an air or fluid-filled pad sensor 10, shown from the side (beneath an infant 100) and from the top. FIG. 4A illustrates a single chamber pad sensor. FIGS. 4A-4C show different configurations of multiple chamber pad sensors, where lines or a grid indicate the separate chambers. Each chamber may be connected to a separate pressure sensor or multiple chambers may be connected to a single pressure sensor (not shown). The dark ovals in each panel represent conventional structures within the mattress. The pad may include any number of ribs, which may be part of the individual chambers. In some embodiments, the pad includes a single chamber. In other embodiments, the pad includes at least two chambers. In related embodiments, the pad includes a plurality of chambers. Where the pad sensor includes a plurality of chambers, the chambers may be vertically or horizontally stacked. The subject may rest on a stack of chambers or may rest on several adjacent chambers.
FIG. 5 illustrates and embodiment that employs an air or fluid-filled pad 10 for monitoring a subject's 100 cardiac and/or respiratory function and an ambient null sensor device 50 for monitoring ambient motion in the vicinity of the subject 100. The air or fluid-filled pad 10 and ambient null device 50 are separately connected to pressure sensors 30, 31, which provide pressure data for filtering and analysis by a microprocessor 200. The air or fluid pump 20 for filing the pad sensor 10 is indicated. The same or a different pump 20 may be connected to the ambient null device 50 (not shown).
Where an ambient and null device/sensor is used in combination with a pad sensor, the signal from the null device may be subtracted from (i.e., used to “null” or “cancel out”) the signal from the pad sensor, allowing background signal (i.e., noise) subtraction.
In some embodiments, the pad sensor is filed with air. In related embodiments, the pad sensor is filled with an inert gas. In other embodiments, the pad is filled with a fluid. In particular embodiments, the fluid is an aqueous solution or water, optionally with an additive to retard the growth of microorganisms. Preferred fluids are inexpensive and non-toxic. Air-fluid emulsions or hybrid air/fluid configurations should produce similar results.
Pad sensors may be made of virtually any conventional material that is air or water-tight, as required by the particular embodiment. Exemplary materials include but are not limited to plastic (e.g., polyethylene, polypropylene, latex, vinyl, etc.) and fabric (e.g., canvas). Fabrics may be treated with a plastic or other coating to make them air or fluid-tight, as required. The pad may be covered for comfort or protection, so long as the covering does not substantially insulate the sensor from the vibrations generated by the subjects heart and/or lung function.
Where the pad sensor includes multiple chambers (e.g., FIGS. 4B-4D), each chamber may be operably connected to a separate pressure sensor or a plurality of chambers may be connected to a single pressure sensor. Generally, one pad is used for each subject. Where a single pad is used to monitor a plurality of subjects, e.g., as in the case of a large pad for monitoring a plurality of infants or adults, a plurality of chambers is preferred, thereby allowing distinction between the heart and respiratory functions of each subject on the mattress sensor.
The pad may include foam or ribbing to provide structural support, to reduce resonance or harmonics, or to preventing “bottoming out” under the weight of the subject. Foam may also allow for self-inflating of the pad. Ribbing may be the result of compartmentalization or chambers, as described above. Ribbing may also be used to focus the incident waves on the pressure sensor. In some embodiments, the pad sensor is in the form of a “U” shape to force incident waves to the ends of the tube, where the pressure sensor is typically located.
While changes in the dynamic pressure in the pad are used to monitor cardiopulmonary health status data (i.e., vital signs), static pressure in the pad sensor can be used to measure a subject's weight. In this manner, the pad sensor can also be used to provide weight data (e.g., over time), or to detect the presence or absence of the subject on the pad.

B. MECHANICAL PLATE EMBODIMENT

In some embodiments, the cardiac and respiratory functions are monitored using a mechanical plate (or electromechanical) sensor. In a particular embodiment, the plate sensor includes at least one weighted strain gauge for detecting vibrations resulting from cardiac and/or respiratory functions of a subject.
An embodiment of the method and apparatus that employs a strain gauge is shown in FIGS. 8A and 8B. As shown in FIG. 8A, the plate sensor apparatus comprises an upper plate 60 and lower plate 61. The subject 100 rests on the upper plate 60. As shown in FIG. 8B, the upper and lower plates are connected via one or more strain gauges 71, 72, 73, 74, each having a first end 62 attached to the upper plate 60 and a second end 63 attached to the lower plate 61. The strain gauges may be adapted to measure strain in any dimension, such as the X, Y, and Z, axes as shown in FIG. 8B. Strain gauges may also measure the rotation of one plate with respect to the other, the tilting of one plate with respect to the other, or the flexing of the upper or lower plate.
Ballistic movement of the subject in response to heart and lung function is generally not limited to a single direction. In some embodiments, it may be desirable to monitor movement in several directions to increase the sensitivity of the plate sensor. However, it is generally not necessary to monitor movement in all directions. In some embodiments, it may be adequate to monitor movement in one direction. Thus a limited small number of strain gauges, such as 1, 2, 3, 4, 5, or 6 should be sufficient to detect cardiac and/or lung function. The two plates may further be connected by springs, foam, an air or fluid-filled bag or cushion, etc. to maintain a nominal separation distance between the plates. The weight of the intended subject will be reflected in the springs, foam, or other material used to maintain distance between the plates.
FIG. 9 is a schematic diagram showing how an electromechanical sensor is used according to the method and apparatus. Electrical signals from strain gauges or pressure sensors measuring movement in the X 81, Y 82, and Z 83 axes, along with (optionally) electrical signals from other sensors, such as a microphone 84 and temperature gauge 85 are fed into filters 90, received by an analog to digital converter 95, or similar device, and analyzed by a digital signal processor (DSP) 200. The DSP includes preselected or learned/trained parameter information (arrows pointing down towards DSP 200) and may trigger one or more events (arrows point away from DSP 200). The DSP 200 may also communicate with a wireless transceiver 400 for further distributing the processed signal.

C. FURTHER EMBODIMENTS

Combinations of gas/fluid pressure sensors and strain gauges may be used to increase the sensitivity of detection of vibrations resulting from heart and lung function. In addition, other types of sensors may be used in addition to, or in place of, gas/fluid-filled and electromechanical sensors. Cost and practicality should be considered in the design. The above-described sensors offer adequate sensitivity without being overly elaborate in design.
Although preferred health status sensors are non-invasive, non-entangling, and unobtrusive, some embodiments employ a sensor that is worn or attached to the subject, e.g., in the form of a wrist or ankle-worn sensor. Such sensors may be adapted to communicate with a processing or analytical device in a wireless manner, thereby minimizing the intrusive nature of the sensor.

III. Additional Sensors

In addition to the pad or plate sensor for detecting vibrations from heart function and/or breathing, the method and apparatus may include one or more additional sensors for obtaining health status or environmental data. Such additional sensors include but are not limited to temperature sensors for monitoring ambient temperature and/or the temperature of the subject; light sensors for monitoring ambient light; weight sensors for measuring subject weight, moisture sensors for detecting bed-wetting or other nocturnal emissions; audio and/or video sensors for detecting crying, fussing/complaining, snoring, tossing and turning, position indicators for detecting changes in mattress angle, changes in the subjects orientation, etc.
Exemplary additional sensors include microphones, cameras, thermometers, photoelectric devices, microelectromechanical sensors (MEMS), sphygmomanometers, strain gauges, accelerometers, inclinometers, altimeters, barometers, radiation detectors, moisture gauges, and the like. In some embodiments, the additional sensors obtain data in a non-invasive manner, much like the pad sensor. In other embodiments, the additional sensors are connected to the subject. Data from such additional sensors can be used passively, i.e. recorded for later use; sent periodically to web pages or cell phones; displayed on a monitor, etc. Data from such devices can also be used actively, i.e. used to determine ambient light, detect motion via frame differencing, triggering an alarm, etc. Exemplary additional sensors are exemplified, below:
A. Ambient Light Monitors
Ambient light monitors (photo detectors, photo diodes, CCD integrators, etc.) can be used to capture and track the amount of light in the room occupied by the subject. By looking at the spectral components, it is also possible to determine if the source is natural or artificial light.
B. Video Capture Device
Video capture devices, such as visible-light or infrared (IR) cameras, can be used to take snapshots, time lapse images, or continual frames of the subject. In some embodiments, data from a video capture device is used to trigger a wake-up alarm, turn on or off lights, etc. Data from an infrared detector may be used to monitor the temperature of a subject. Video data may also be used to determine the position of a person or animal, as well as when the person/animal has turned over.
C. Audio Sensors
Audio sensors, such as microphones, can be used to identify crying, coughing, snoring, screaming, hiccoughing, groaning, and/or “fussiness.” Microphones are well known in the art.
D. Temperature Sensors
Temperature/thermal/IR sensors can be used to monitor ambient room temperature and/or a subject's body temperature. Where the temperature sensor measure a subject's temperature, it may be placed on the top of the mattress sensor or built into the pad or plate sensor. Non-contact thermometers are particularly useful for measuring a subject's body temperature.
E. Chemical Sensors
Chemical sensors can be used for warning and/or diagnosis. For example, carbon monoxide, carbon dioxide, oxygen, natural gas, methane, hydrogen sulfide, and ammonia sensors can be used to identify life threatening environmental conditions caused by, e.g., poor ventilation, smoke, fire, etc. Chemical sensors may also be used to monitor flatulence or metabolic conditions that result in the production of detectable chemical species (e.g., ketosis, trimethylaminuria). A carbon dioxide sensor may be utilized to determine if an infant has rolled over onto its front, a potential condition for suffocation. A vast number of chemical sensors are available, depending on the chemicals likely to be present in the particular environment.
F. Weight Sensors
In some embodiments, it may be desirable to monitor a subject's body weight in addition to the subject's cardiac and/or respiratory function. Body weight monitoring is readily accomplished using a conventional scale, which is typically placed under the mattress sensor.
Body weight may also be determined from the average (i.e., static as opposed to dynamic) pressure in the pad sensor or on the plate sensor, which corresponds to the weight of the subject. In this manner, the pad or plate sensor may serve as both a cardiac function/breathing monitor and a weight sensor (or scale).
G. EKG/EEG
Electrocardiographs (EKG; ECG) may be used to supplement data from the pad sensor, to calibrate the pad sensor, or to detect particular cardiac abnormalities.
In some embodiments, electroencephalograph (EEG) data is obtained from a subject to monitor brainwaves. This embodiment is particularly useful for studying sleep patterns in subjects and for monitoring subjects for brain activity following a stroke, heart attach, or trauma.
H. Movement Sensors
In some embodiments, movement (or motion) sensors are used in combination with the pad or plate sensor to detect the presence of the subject in the room, to determine whether a crib, bed, chair, sofa, etc. is occupied, to monitor gross subject movements. Movement sensors include inclinometers, accelerometers, photodetectors, and the like.

IV. Ambient Null Sensor Device

In some embodiments, the pad or plate sensor is used in combination with an ambient (or null) sensor device for measuring ambient motion in the vicinity of the subject. In preferred embodiments, the ambient null device is similar to the pad or plate sensor for monitoring cardiopulmonary vibrations, differing in that the subject does not rest on the ambient null sensor. In other embodiments, the ambient null device is a device different from the pad or plate sensor, including but not limited to an accelerometer or bob weight device.
The ambient null device is used as a “control” for environmental changes that are not due to movement of the subject in question. The signal/data from the ambient null sensor can be subtracted from that of the pad or plate sensor to reduce background noise and account for changes in the environment in which the subject is resting on the pad or plate sensor.
In preferred embodiments, the ambient null device incorporates a sensor similar to that of the pad or plate sensor, such that the data produced are comparable. In some embodiments, the sensor is of the same type or model. Alternatively, the ambient null sensor is of a different type that the pad or plate sensor, including any of the sensor types described herein.
Not all embodiments of the present method and apparatus require use of an ambient null device/sensor. Vibrations resulting from heart function and breathing are regular and rhythmic and not easily confused with ambient noise; therefore, it should generally not be necessary to use an ambient sensor device unless suitable analog or digital filters, including software filters, cannot be designed. Ambient null devices are generally only required where background noise (including noise from other human or animal subjects) interferes with detection and monitoring of cardiac function and/or respiration.

V. Data Processing

Raw data from a pad or plate sensing unit and, optionally, other sensor(s) and inputs, are processed to produce processed data. Processing may be by analog means or by digital means.
FIG. 6 shows a typical data processing arrangement. Input data from, e.g., one or more pressure sensors or strain gauges 61 and optional additional sensors 62 are filtered using band- pass filters 63, 64, 65, amplified, and digitized, e.g., using an analog to digital converter 66. The filtered signals are then sent to a DSP 67 for further processing and/or analysis. The DSP 67 may trigger alerts, alarms, or events directly and/or may be sent to a remote location using a wireless transceiver 68. The remote location may be, e.g., the internet or a remote monitor. In other embodiments, input data is first digitized and then filtered or otherwise processed. Data from different sensors may be processed differently.
FIG. 7 shows exemplary cardiopulmonary data obtained from an infant placed on a pad sensing unit as described. The raw sensor data were processed through a 10 Hz low-pass filter, amplified, digitized, digitally band-passed, and then fed to a fast Fourier transformer to convert the data to the frequency domain. Similar results could have been obtained by amplifying and digitizing the raw signal and using a digital/software low-pass filter. Since the beating frequency of a human heart is approximately 50-200 beats per minute (0.83-3.33 Hz) the frequency range of interest for monitoring human (and many other animal) heart rates is from about 0.1 to about 10 Hz, or from about 1 to about 5 Hz, or even from about 2 to about 5 Hz. Since the respiration/breathing frequency of a human is about 10-20 breaths per minute (0.16-0.33 Hz) the frequency range of interest for monitoring human (and many other animal) breathing rates is from about 0.1 to about 1 Hz but generally less than about 1 Hz.
Analog and/or digital filters can be used to select any portion of a signal for analysis. Other frequency ranges may be of interest, e.g., for monitoring coughing, screaming, hiccoughing, snoring, groaning, turning, flipping, shivering, shaking, convulsions, movements in dreams, erotic stimulation, or other movement.
Processed data can be analyzed by a microprocessor and used to trigger an event or event set, such as alerting medical professionals to assist in identifying, preventing, or treating the subject, sounding an alarm, etc, as described. The event set that is triggered depends on the rules created or tailored by the user. Examples include sending a message via the internet, logging an entry in a log file, changing a database entry, and the like. Data can also be recorded, with our without accompanying analysis, for later reviewed.
The present method and apparatus are ideally integrated with internet/web-based services, wireless telecommunications, advanced audio and video processing, instant messaging, digital and analog signal processing, medical record databases and patient records, and private and public health agencies.
Where the method and apparatus are connected to the internet, filters and/or microprocessors used to process raw data and/or analyze processed data may be at a location remote from the sensing unit. In one embodiment, raw data are transmitted via an internet connection to a microprocessor associated with a server. In another embodiment, data processed by a local microprocessor are transmitted via an internet connection to a microprocessor associated with a server.

VI. External Devices and Platforms

In some embodiments, it may be desirable to use in the present method and apparatus in combination with an external device or platform, such as a text messaging platform, data logger, printer, alarm system, alert siren, or other data acquisition or actuating device; or a computer (i.e., microprocessor) capable of performing analytical functions.
In some embodiments a message platform is used for delivery of data, messages, alarms, and alerts. These messages may take, for example, the form of text messages (short message service, SMS) sent by way of telephone services, email, voice calls, and in home monitoring media including audio, video, and heart and breathing sounds, either in the form of direct audio, or simulated sound processes. Telephone services utilized by embodiments of the invention may include either or both the public switch telephone network (PSTN) connections and cellular telephone connections as well as a IP network connection.
Alarms or alerts may be triggered by processed signal data that are outside normal values or meet pre-selected user trigger points. Such alarms or alerts may be delivered by a telephone, web, or other service, as described. Alarms or alerts may be sent to e.g., pre-selected health care professionals (including paramedics, physicians, nurses, police, and the like), relatives and/or guardians, public health agencies, child services, etc., as determined by the user. Simple alarms or alerts are audible and/or visible signals, such as horns, buzzers, sirens, lights, and the like.
Alarms, alerts, and/or panic signals may also be localized to particular places in a home, hospital, elderly, care facility, or infant care facility. Such signals may transmitted by wired or wireless technology, such as cabling, WiFi, Zigbee, Bluetooth, etc., for contacting receiving devices such as cell phones or personal digital assistants (PDAs).
Some embodiments may also include a “panic button” that can be manually activated by the subject or another person. The panic button may cause a signal to be sent to pre-selected health care professionals, relatives and/or guardians, public health agencies, child services, etc., as above. As above, the signal can be sent via a telephone, the web, or another service, as described.
In some cases, it may be desirable to trigger an automatic action in response to processed data. For example, it may be desirable to disturb a subject's sleep with an audible and/or visible signal or through vibration, shaking, or physical contact with the subject. In other embodiments, pre-selected health status data causes, e.g., medication to be dispensed to a patient, a respirator to begin pumping air, a defibrillator to restart a subject's heart, a portion of a mattress to be raised or lowered, etc.
In some embodiments, the external device is a data logger or recording device for keep track of a subject's health status data. In other embodiments, a printer of chart recorder is connected. Most any of the described external devices can be used in combination.
FIG. 10 shows an exemplary system in which data from a pad or plate sensor (and optional additional sensors) is communicated to a microcontroller 92 via a wireless transceiver 91. The microcontroller 92 analyzes the data, which may be viewed or presented on a remote monitoring device 93, in addition to being sent to the internet, being used to trigger event sets, etc. The remote monitoring device could be located, for example, in a physician's office, a nurse's station, a fire department or paramedic station, a parent's or guardian's bedroom, etc.
In all cases, the method and apparatus make include two-way (or more) communication between subject and a remote monitoring location. The two-way communication may be audio, e.g., using microphones and speakers; video, e.g., using cameras and monitors; or text, e.g., using email, messaging, or the like.

VII. Internet Connectivity

Embodiments of the method and apparatus include a web portal, as part of the monitoring capability. The web portal is supported by a web server through which users may access the web. Connection to a web portal also provides access to a back-end server to capture, store, and analyze data from the various sensors of the system. The web portal typically includes an interface for the user to set various pre-selected parameters, such as which data triggering alerts or alarms.
In some embodiments, the interface provides access to a user's account (typically the subject's account), where preferences are pre-selected, and where billing and management are handled. The interface may further provide storage, presentation, and delivery of data that have been recorded. The data may be annotated with, for example summaries and analyses. The web portal may further provide drug recommendations, advertising material, news, tips, or other information based on health status data collected from the subject.
Connectivity to the internet and/or local area networks permits the pad or plate (or additional) sensors of the present method and devices to be linked to patient/invalid monitoring devices, alert services, and web applications for transmitting, receiving, and storing health data. In particular embodiments, the method and device are used to provide alerts or alarms in response to an adverse cardiovascular or respiratory event. Alerts generated by the system may be directed to health care professionals, family members, to a data logging device, or to emergency service agencies such at police, fire, ambulance, medic, etc.
In some embodiments, a web-based service specifically designed to monitor a plurality of subject using separate pad or plate sensors, is provided. The subjects may be in different locations. The web service may analyze data and determine a course of action, which can include any of the alerts, alarms, or events described.

VIII. Patient Populations and Settings

The invention provides a method and apparatus for the non-invasive, non-entangling, and unobtrusive health status monitoring of a subject in a home or health care institutional setting, particularly with respect cardiovascular health status. A healthcare institutional setting may be a physicians's office, hospital, clinic, nursing facility, veterinary clinic, or assisted living facility, by way of examples.
The method and apparatus may be used to monitor “vital signs” or other health status data. As used herein, vital signs include but are not limited to respiratory (breathing) rate, the concentration of respired gases, pulse rate, blood pressure, and cardiac electrical activity.
In some embodiments, the method and apparatus may be used to monitor and thus protect the health and lives of infants at risk for the occurrence of sudden infant death syndrome (SIDS). However, those skilled in the art will recognize that method and apparatus are applicable to children, adolescents, adults, the elderly, senior, and animals. For example, adults considered at risk for sleep apnea or adverse cardiovascular events may be monitored using the present method and apparatus. Embodiments may be designed to protect individuals at rest, asleep, or untended. Humans or animals being monitored may be referred to as a “patient” or “subject,” and may be of any age or health status.
The methods an apparatus may also be used to study dream behavior, to monitor a subject's bathroom usage or frequency of changing position in bed, to monitor the amount of time a subject spends in a bed chair, couch, etc, to monitor the frequency and/or severity of convulsions or apneas, to monitor the frequency and/or severity of arrhythmias, or to monitor a bed or other surface for evidence of erotic stimulation.
The methods and apparatus may also be used to determine whether a subject is present in a particular location. In this manner, health-status data may be used to identify a particular subject (e.g., via pattern recognition) to confirm the identity of the subject in the location. The health-status data may also be used only to indicate the presence of any subject in a particular location, e.g., to make sure a baby is in a crib, an elderly patient is in a bed, or a dog is in a kennel, without identifying the subject.
Further embodiments and variation using the present method and apparatus will be apparent to the skilled artisan in view of the disclosure. The methods are apparatus are in no way limited by the description.

Claims

1. Apparatus for monitoring heart and respiration rates of a human subject at rest, comprising, in operative condition,

(a) a sensing unit having (i) a fluid or gas-filled pad adapted to be placed on a bed, crib, or chair support, for cushioning at least an upper body portion of a subject lying on or resting against the support, mattress or cushion, and (ii) a pressure sensor in gas or fluid communication with gas or fluid in said unit, for generating electrical signals in response to pressure variations within the gas or fluid in the pad, and

(b) a monitoring unit operatively connected to said pressure sensor, for (i) receiving signals therefrom, (ii) generating from said signals, information about the heart and respiration rates of the subject, and (iii) relaying such information to a monitoring station or individual.

2. The apparatus of claim 1, wherein the pad is a fluid-filled pad.

3. The apparatus of claim 1, wherein the pad is a gas-filled pad.

4. The apparatus of claim 1, which further includes a pressure-control unit comprising a pump in fluid or gas communication with the pad and a controller operatively connected to the pump for maintaining fluid or gas within the pad at a selected pressure or within a defined pressure range.

5. The apparatus of claim 1, wherein said pad comprises a single fluid or gas-filled chamber, having a pressure sensor in fluid or gas communication therewith, for generating electrical signals in response to pressure changes within the chamber.

6. The apparatus of claim 1, wherein said pad includes at least two independent, fluid or gas-filled chambers, each of which has a pressure sensor in fluid communication therewith, for generating electrical signals in response to pressure changes within the associated chamber.

7. The apparatus of claim 1, which further includes an ambient-null device comprising a fluid or gas-filled ambient pad, a weight carried on the ambient pad, for exerting pressure thereon, and an ambient pressure sensor in fluid or gas communication with fluid in the ambient pad, for generating electrical signals in response to pressure changes within the fluid or gas, in response to ambient motion in the vicinity of the subject, wherein said monitoring unit is operatively connected to said ambient pressure sensor, for (i) receiving signals therefrom, and (ii) processing the signals received from the first-mentioned and ambient pressure sensors, to filter such ambient motion from motion related to the subject's heart and respiration rates.

8. The apparatus of 1, wherein said monitoring unit includes a processor operative to (i) generate heart-rate information of the subject, based on time-dependent signals having frequency components in the range from about 0.1 to about 10 Hz, and (ii) generate respiration rate information of the subject based on time-dependent signals having frequency components in the range less than about 1 Hz.

9. The apparatus of claim 8, wherein the information generated by the signal processor further includes blood-pressure information.

10. The apparatus of claim 9, wherein said pad includes upper and lower independent, fluid or gas-filled chambers, each of which has a pressure sensor in fluid communication therewith, for generating electrical signals in response to pressure changes within the associated chamber, and the information generated by the processor includes information about the orientation of the individual with respect to the pad, based on a characteristic ventral, dorsal or lateral signals produced by processing the two separate signals generated for the two chambers.

11. The apparatus of claim 8, wherein said monitoring unit includes a remote monitor, and a transmitter for transmitting such heart and respiration rate information from the processor to the monitor.

12. The apparatus claim 1, wherein said pad further includes temperature sensor for measuring the temperature of the individual on the pad.

13. A sensor unit for use with a monitoring unit, for monitoring heart and respiration rates of a human subject at rest, comprising, in operative condition,

(a) a fluid or gas-filled pad adapted to be placed on a bed, crib, or chair support, for cushioning at least an upper-body portion of a subject lying on or resting against the support, and

(b) a pressure sensor in fluid communication with fluid in said unit, for generating electrical signals in response to pressure variations within the fluid or gas, and adapted to be operatively connected to such a monitor.

14. The sensing unit of claim 13, wherein said pad includes as single fluid or gas-filled chamber having a pressure sensor in fluid of gas communication therewith, for generating electrical signals in response to pressure changes within the chamber.

15. The sensing unit of claim 13, wherein said pad includes at least two independent, fluid-filled chambers, each of which has a pressure sensor in fluid or gas communication therewith, for generating electrical signals in response to pressure changes within the associated chamber.

16. The sensing unit of claim 13, wherein for the pad is a fluid-filled pad.

17. The sensing unit of claim 13, wherein for the pad is a gas-filled pad.

18. A method for monitoring vital signs, including heart and respiration rates, of a human subject lying on or resting against a bed, crib, or chair support, comprising

(a) placing between the subject and the support, a fluid or gas-filled pad positioned for cushioning at least an upper-body area of the subject,

(b) generating electrical signals in response to pressure variations within the fluid or gas by a pressure sensor in fluid communication with fluid or gas in said pad, and

(c) processing the electrical signals received from the pressure sensor to generate information about the heart and respiration rate of the subject.

19. Apparatus for remotely monitoring heart and respiration rates of a human subject lying on or resting against a bed, crib, or chair support, comprising

(a) a pad adapted to the placed between the subject and the support, for cushioning at least an upper body portion of the individual,

(b) a sensor on said pad for generating motion-related signals caused by the subject's heartbeat and breathing,

(c) a processor operatively connected to said sensor, for (i) receiving time-dependent signals therefrom, and (ii) generating heart-rate information of the subject, based on received time-dependent signals in the range from about 0.1 to about 10 Hz, and respiration rate information of the subject, based on received timed-dependent signals in the range less than about 1 Hz,

(d) a remote monitor for use by an individual in monitoring said subject, and

(e) a transmitter for transmitting such subject information from the processor to the individual.

19. The apparatus of claim 18, which further includes an ambient-motion device for generating signals related to ambient motion in the vicinity of the subject, and said processor is operatively connected to said device, for processing the signals received from the device, to filter such ambient motion from motion related to the subject's heart and respiration rates.

20. Apparatus for monitoring vital signs, including heart and respiration rates, of a human subject lying on or resting against a bed, crib, or chair support, comprising

(a) a pad adapted to the placed between the subject and the support, for cushioning at least an upper body portion of the individual, said pad comprising

(i) a pair of confronting plates, one adapted to be supported on the mattress, and the other adapted for contact with the chest area of the individual, said plates being spaced apart for relative lateral movement in an XY plane and relative vertical movement in the Z direction,

(iii) connecting the two plates, an L-shaped connector attached at opposite ends to the opposing plates and having a pair of laterally extending, orthogonally disposed arms, a strain gauge carried on each arm, in an XY plane, and a strain gauge carried on one of the arms, in a vertical plane, and

(b) a monitoring unit operative to transmit to a remote user, information about the heart rate of the individual, based on signals received from the pad's lateral-movement strain gauge devices, and about the respiration rate of the individual, based on signals received from the pad's vertical-movement strain gauge(s).

21. The apparatus of claim 20, wherein said two opposing plates are substantially rectangular, and connected by said L-shaped connectors in the region of each of the four corners of the two plates.

22. The apparatus of claim 21, which further includes a vertical-movement strain gauge connecting the two plates, for generating information about the weight applied by the individual on the pad.

23. The apparatus of claim 21, wherein said monitoring unit includes a processor operative to (i) wherein said monitoring unit includes a signal processor operative to (i) generate heart-rate information of the subject, based on time-dependent signals received from each of the plural lateral-movement strain-gauge devices, and having frequency components in the range from about 0.1-10 Hz, and (ii) generate respiration rate information of the subject based on timed-dependent signals having frequency received from the at least one of the vertical-movement strain gauge(s), and having frequency components in the range less than about 1 Hz.

24. The apparatus of claim 23, wherein said monitoring unit includes a remote monitor, and a transmitter for transmitting such heart rate and respiration rate information from the processor to the monitor.

25. The apparatus claim 24, wherein said pad further includes temperature sensor for measuring the temperature of the individual on the pad.

26. The apparatus of claim 24, which further includes a weighted strain gauge adapted for attachment to the bed or crib, independent of said pad, for detecting movement of the bed or crib, independent of movement within the pad, and the monitoring unit is operative to remove such independent movement from pad movement detected by the pad strain gauges.

27. Apparatus for determining the presence of a subject, comprising:

(a) a sensing unit having (i) a fluid or gas-filled pad adapted to be placed on a bed, crib, or chair support, for cushioning at least an upper body portion of a subject lying on or resting against the support, mattress or cushion, and (ii) a pressure sensor in fluid communication with fluid in said unit, for generating electrical signals in response to pressure variations within the fluid in the pad, and

(b) a monitoring unit operatively connected to said pressure sensor, for (i) receiving signals therefrom, (ii) generating from said signals, information about the presence of the subject and (iii) relaying such information to a monitoring station or individual.

28. A sensor unit for use with a monitoring unit, for detecting the presence of a subject, comprising:

29. A method for detecting the presence of a subject on or in a bed, crib, or chair support, comprising:

(a) placing on or in the bed, crib, or chair support a fluid or gas-filled pad positioned for cushioning at least an upper-body area of the subject,

(c) processing the electrical signals received from the pressure sensor to generate information about the presence of the subject.

30. Apparatus for monitoring the presence of a subject lying on or resting against a bed, crib, or chair support, comprising:

(b) a monitoring unit operative to transmit to a remote user, information about the presence of the subject, based on signals received from the pad's strain gauge devices.