U.S. patent application number 10/915285 was filed with the patent office on 2005-01-13 for device for monitoring a vital sign.
Invention is credited to Glick, Baruch, Itzhaki, Aviran, Kopel, Doron, Palti, Yoram, Urbach, Israel, Wasserman, Yoram.
Application Number | 20050010119 10/915285 |
Document ID | / |
Family ID | 8171626 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050010119 |
Kind Code |
A1 |
Palti, Yoram ; et
al. |
January 13, 2005 |
Device for monitoring a vital sign
Abstract
A device (1) for monitoring a vital sign of a living subject,
comprising a measuring unit (2) for measuring at least one physical
quantity indicative of said vital sign at an area (8) overlying an
artery (7) of the subject, which measuring unit (2) is provided on
a carrier (3) to be worn by the subject during operation, and a
processing unit (4) for processing the measured physical quantity
into a value for the vital sign, which device (1) is provided with
at least one detector (5) for detecting the position of the
measuring unit (2) relative to the artery (7) of the subject during
operation and for actuating a feedback signal (Ufeedback) in
dependence on this position. The user can move the device (1)
relative to the artery (7) until the feedback signal (Ufeedback) is
given, and thus a correct positioning of the measuring unit (2)
relative to the artery (7) is achieved in an easy manner.
Inventors: |
Palti, Yoram; (Haifa,
IL) ; Wasserman, Yoram; (Haifa, IL) ; Glick,
Baruch; (Haifa, IL) ; Itzhaki, Aviran; (Haifa,
IL) ; Kopel, Doron; (Zechron J'Aakov, IL) ;
Urbach, Israel; (Haifa, IL) |
Correspondence
Address: |
PHILIPS INTELLECTUAL PROPERTY & STANDARDS
P.O. BOX 3001
BRIARCLIFF MANOR
NY
10510
US
|
Family ID: |
8171626 |
Appl. No.: |
10/915285 |
Filed: |
August 10, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10915285 |
Aug 10, 2004 |
|
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|
09862290 |
May 22, 2001 |
|
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6811535 |
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Current U.S.
Class: |
600/499 ;
600/503 |
Current CPC
Class: |
A61B 5/417 20130101;
A61B 5/02233 20130101; A61B 5/14557 20130101; A61B 5/024
20130101 |
Class at
Publication: |
600/499 ;
600/503 |
International
Class: |
A61B 005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2000 |
EP |
00202064.2 |
Claims
1. A device (1) for monitoring a vital sign of a living subject,
comprising a measuring unit (2) for measuring at least one physical
quantity indicative of said vital sign at an area (8) overlying an
artery (7) of the subject, which measuring unit (2) is provided on
a carrier (3) to be worn by the subject during operation, and a
processing unit (4) for processing the measured physical quantity
into a value for the vital sign, characterized in that the device
(1) is provided with at least one detector (5) for detecting the
position of the measuring unit (2) relative to the artery (7) of
the subject during operation and for actuating a feedback signal
(Ufeedback) in dependence on this position.
2. A device as claimed in claim 1, characterized in that the
detector (5) comprises at least one sensor for detecting the
presence of the artery (7) in the vicinity of the sensor, which
sensor is chosen from a group comprising electro-optical sensors
and ultrasound sensors.
3. A device as claimed in claim 2, characterized in that a
plurality of sensors (10, 11) for detecting the presence of the
artery (7) in the vicinity of the sensor (10, 11) are provided in
an array.
4. A device as claimed in claim 1, characterized in that the
feedback signal (Ufeedback) is chosen from a group comprising audio
and visual signs.
5. A device as claimed in claim 1, characterized in that the
carrier (3) comprises an annular body (3') which is at least partly
rigid.
6. A device as claimed in claim 1, characterized in that the
carrier (3) comprises an annular body (3") which is entirely
rigid.
7. A device as claimed in claim 1, characterized in that the
measuring unit (2') comprises an inflatable cushion (13) for
applying a pressure to said area (8) overlying said artery (7) of
the subject, and the cushion (13) comprises a plurality of
separately inflatable cushion parts (14).
8. A device as claimed in claim 8, characterized in that the
cushion parts (14) comprise protuberances (24) which project from a
surface area (15) of the carrier (3) in a direction practically
perpendicular to said surface area.
9. A device as claimed in claim 8 or 9, characterized in that the
carrier (3) comprises an annular body (16) which can be closed
during operation, the cushion (13') being provided along an entire
inner wall of said body (16).
Description
[0001] The invention relates to a device for monitoring a vital
sign of a living subject, comprising a measuring unit for measuring
at least one physical quantity indicative of said vital sign at an
area overlying an artery of the subject, which measuring unit is
provided on a carrier to be worn by the subject during operation,
and a processing unit for processing the measured physical quantity
into a value for the vital sign.
[0002] A device of the type defined in the opening paragraph is
known from U.S. Pat. No. 4,660,566.
[0003] The known device is a device for monitoring a vital sign,
the vital sign monitored by this device being a blood pressure of a
subject. The known device comprises a measuring unit comprising a
sensor provided on an inflatable cushion, and a processing unit.
This cushion is provided on a carrier comprising a bracelet of
flexible material worn by a user around his or her wrist. The
sensor measures a physical quantity indicative of the blood
pressure at an area overlying an artery of the subject. To measure
the physical quantity effectively, the sensor on the cushion has to
be positioned correctly relative to the artery. Therefore the
sensor on the cushion is positioned relative to the artery on the
wrist during operation, by means of a strap which is wound around
the thumb of the subject and which is interlocked with a strip on
the bracelet. Further locking strips are attached to the flexible
bracelet to maintain the bracelet in this position. In this known
device, pressure pulses are applied by means of the cushion to a
local, discrete external point overlying the radial artery of the
subject so as to effect a blocking or an unblocking condition of
the artery. When the sensor detects said condition, the
instantaneous value of the pressure in the cushion is measured, for
providing through the processing unit a value of said subject's
blood pressure. A disadvantage of the known device is that a
correct positioning of the sensor relative to the artery is not
guaranteed, and thus a "correct" measurement could in fact be
incorrect. This is highly undesirable both in the monitoring of a
vital sign by a professional in a professional situation, and in a
domestic situation, where the measurement is carried out by a
person him- or herself.
[0004] It is an object of the invention to provide an improved
device for monitoring a vital sign of a subject which is easy to
use and is correctly placeable relative to the artery.
[0005] To achieve this object, a device according to the invention
is characterized in that the device is provided with at least one
detector for detecting the position of the measuring unit relative
to the artery of the subject during operation and for actuating a
feedback signal in dependence on this position. A user of the
device knows that a correct position of the measuring unit relative
to the artery is reached when the feedback signal is given. The
user can move the device relative to the artery until the feedback
signal is given, and thus a correct positioning of the measuring
unit relative to the artery is achieved in an easy manner. Next to
that, the structure of the device is simpler, because no additional
fastening parts are necessary in the device for achieving a correct
positioning of the measuring unit.
[0006] An embodiment of a device in accordance with the invention
is characterized in that the detector comprises at least one sensor
for detecting the presence of the artery in the vicinity of the
sensor, which sensor is chosen from a group comprising
electro-optical sensors and ultrasound sensors. These sensors work
efficiently and can be easily integrated within the device, while
the comfort of use of the device is maintained.
[0007] It is furthermore advantageous when a plurality of sensors
for detecting the presence of the artery in the vicinity of the
sensor are provided in an array. One given sensor in the array will
detect the presence of the artery in the case of a correct position
of the measuring unit relative to the artery. A number of sensors
in the array will not detect the presence of the artery, but at
least one sensor will when the device is placed with its measuring
unit on the artery. Thus an indication can be given to the user
through the sensors in which directions the device should be moved
for said given sensor to detect the presence of the artery.
Furthermore, the detector can be varied with respect to its
structure and size through combining of arrays of sensors,
depending on the type of device for monitoring vital signs in which
the detector is applied.
[0008] An embodiment of a device in accordance with the invention
is characterized in that the feedback signal is chosen from a group
comprising audio and visual signals. Audio and visual signals are
easily recognizable for users. Furthermore, the freedom is created
to adapt the feedback signal to the demands of the varying types of
devices for monitoring vital signs and to the demands of varying
user groups of the device.
[0009] It is advantageous when the carrier comprises an annular
body which is at least partly rigid, and especially when the
annular body is entirely rigid. The rigid annular body simplifies
the placement of the measuring unit on the subject whose vital
signs are to be monitored. The rigid annular body has a fixed shape
corresponding to the body part of the subject it is to be placed
on, so that its placement can be performed in a clear and
unambiguous way. Next to that, the rigid annular body contributes
to the correct positioning of the measuring unit relative to the
artery of the subject. It offers a first rough positioning of the
annular body with the measuring unit on the subject, while the
positioning of the measuring unit relative to the artery of the
subject is further refined by shifting of the annular body relative
to the artery over small distances in reaction to the feedback
signal actuated by the detector. Furthermore, particularly if the
measuring unit comprises an inflatable cushion, the rigid annular
body bounds the level of expansion of the inflatable cushion, so
that the cushion cannot be excessively inflated during operation.
This benefits an effective application of pressure by the cushion
to the area overlying the artery.
[0010] An embodiment of a device in accordance with the invention
is characterized in that the measuring unit comprises an inflatable
cushion for applying a pressure to said area overlying said artery
of the subject, and the cushion comprises a plurality of separately
inflatable cushion parts. During operation each cushion part can
apply pressure locally on said area overlying said artery of the
subject. The transmission of said pressure is thus less disturbed
by the structure of the area, comprising bones and tendons, because
the cushion parts can enter between the bones and tendons. Once the
cushion has been positioned correctly relative to the artery with
use of the detector, this pressure is applied to the area overlying
the artery of the subject in an efficient way.
[0011] An embodiment of a device in accordance with the invention
is characterized in that the cushion parts comprise protuberances,
projecting from a surface area of the carrier in a direction
practically perpendicular to that surface area. In this way, the
separately inflatable cushion parts are finger-shaped elements
protruding from the carrier, which benefits an efficient
application of local pressure by each cushion part to said area
overlying said artery of the subject.
[0012] With the cushion comprising a plurality of separately
inflatable cushion parts, it is advantageous when the carrier
comprises an annular body which can be closed during operation, and
when the cushion is provided along an entire inner wall of said
body. The cushion parts penetrating between bones and tendons are
also advantageous for applying an annular pressure to an extremity
of a subject, as in known other blood pressure monitors.
[0013] The invention will be described in more detail hereinafter
with reference to the drawings, in which
[0014] FIG. 1 is a perspective view of a first embodiment of a
device according to the invention,
[0015] FIG. 2 is a diagrammatic view of a cross-section of the
device of FIG. 1 provided on a wrist of a living subject, taken on
the line II-II,
[0016] FIGS. 3a and 3b diagrammatically show a detector of the
device of FIG. 1, and a detector of a second embodiment of a device
according to the invention, respectively,
[0017] FIG. 3c diagrammatically shows a cross-section of the
detector of FIG. 3b, taken on the line IIIc-IIIc,
[0018] FIG. 4 shows in functional blocks a processing of a signal
detected by a detector into a feedback signal in the device of FIG.
1,
[0019] FIG. 5 is a perspective view of a third embodiment of a
device according to the invention, provided on a wrist of a living
subject,
[0020] FIG. 6 is a perspective view of a measuring unit of a fourth
embodiment of a device according to the invention,
[0021] FIG. 7 is a perspective view of a measuring unit of a fifth
embodiment of a device according to the invention, and
[0022] FIG. 8 is a perspective view of a carrier of a sixth
embodiment of a device according to the invention.
[0023] FIGS. 1 and 2 show a first embodiment of a device 1 for
monitoring a vital sign according to the invention, including a
measuring unit 2 for measuring at least one physical quantity
indicative of said vital sign at an area 8 overlying an artery 7 of
a living subject. The measuring unit 2 is provided on a carrier 3
to be worn by the subject during operation, which carrier in this
embodiment comprises a band 3' worn by the subject around a wrist
6. In this embodiment, the area overlying an artery where the
measuring unit 2 measures the physical quantity is the area 8
overlying the radial artery 7 of the subject. Furthermore, a
processing unit 4 for processing the measured physical quantity
into a value for the vital sign is included in the device 1. The
device 1 is provided with at least one detector 5 for detecting the
position of the measuring unit 2 relative to the artery 7 of the
subject during operation and for actuating a feedback signal in
dependence on this position. In this way a user of the device 1 can
move the device 1 relative to the artery until the correct position
of the measuring unit 2 relative to said artery 7 is reached,
reacting to the feedback signal generated by the detector 5
detecting the position of said artery 7. Thus a correct positioning
of the measuring unit 2 relative to the artery is achieved in an
easy manner. The detector 5 comprises at least one sensor,
preferably chosen from a group comprising electro-optical sensors
and ultrasound sensors, and preferably a plurality of sensors are
provided in an array. One sensor in the array is pre-determined to
actuate a feedback signal indicating that a correct position of the
measuring unit 2 relative to the artery 7 has been reached, when it
detects the presence of the artery 7. When the device 1 is placed
on the artery 7 with its measuring unit 2, a number of sensors in
the array will not detect the presence of the artery but at least
one sensor will. Thus an indication can be given to the user
through the sensors in which directions the device 1 should be
shifted for the previously determined sensor to detect the presence
of the artery, which indicates a correct positioning.
[0024] FIGS. 3a and 3b show a detector 5 of the device of FIG. 1,
and a detector 5' of a second embodiment of a device according to
the invention, respectively. The detectors 5 and 5' comprise a
configuration of arrays of electro-optical sensors 10 with a light
source 11, here a Light Emitting Diode. To prevent relative
movement between the LED and the sensors, they are located on a
rigid support 20. The distance between the LED and each sensor is
preferably 2 to 5 mm for good operation. The sensors are separated
from each other by a small wall 30 which extends perpendicularly
from the rigid support 20, as can be seen in FIG. 3c, in order to
avoid direct light reflections between the LED and the sensors.
[0025] The sensors 10 and the LEDs are further connected to a
flexible printed circuit board which comprises the processing unit
4 and is not shown in any detail. During operation, each LED emits
light to an area on which the measuring unit 2 contacts the wrist,
which area produces a certain reflection of the light originating
from the LED. When the user moves the device 1 relative to the
wrist, a change in this reflection of light occurs when an artery
is present beneath the detector, because the blood present in the
artery absorbs a certain amount of the light. The electro-optical
sensors 10 detect this change and actuate an output signal
corresponding to it.
[0026] As can be seen in the diagram of FIG. 4, this output signal
is directed to the processing unit 4. First it is amplified by an
amplifier 41, after which a digital signal processing part 42 of
the processing unit 4 processes the signal and estimates the
location of the measuring unit 1 relative to the artery, based on
the relative strengths of the signals of the sensors. Based on this
estimation, a feedback signal Ufeedback is created and transmitted
to the user by an audio or visual unit 43, to guide the user in
positioning the measuring unit 2 correctly relative to the artery.
It is noted that the configuration of the detector 5 and the number
of sensors and light sources used in that configuration may be
chosen freely, depending on the type of device they are applied in.
For example, a combination of two of the detectors from FIG. 3a has
been proven to offer good results in correctly positioning the
measuring unit in a wrist blood pressure monitor relative to the
radial artery of a subject.
[0027] It is further noted that the detector comprising
electro-optical sensors together with the light source, as
described in this embodiment, can fulfil a double function when
applied in the known device for monitoring blood pressure as
described in the prior art. On the one hand, the detector detects
the position of the measuring unit relative to the artery of the
subject during the placement of the device on the wrist and
actuates a feedback signal according to this position. On the other
hand, the detector can further serve to detect the blocking or
unblocking condition of the artery, during the monitoring of blood
pressure with the known device upon which detected condition the
measuring unit measures the instantaneous value of each applied
pressure pulse so as to provide a value of said subject's blood
pressure through the processing unit.
[0028] FIG. 5 shows a third embodiment of a device 1' according to
the invention in perspective view, provided on the wrist 6 of a
person. In this embodiment, the feedback signal Ufeedback comprises
a visual signal formed by directive arrows 34 on a display 12 which
is attached to the carrier 3. In this way, the subject himself can
easily read the directions on the display. He can easily adjust the
position of the device relative to his wrist, following the arrows
34, thus adjusting the position of the measuring unit relative to
the artery until the display confirms a correct position. It is
noted that the feedback signal Ufeedback may alternatively comprise
an audiosignal, for example beeping sounds during positioning and a
ringing sound when a correct position of the measuring unit
relative to the artery is reached.
[0029] FIG. 6 is a perspective view of a measuring unit 2' of a
fourth embodiment of a device according to the invention. The
measuring unit 2' in this embodiment comprises an inflatable
cushion 13 for applying a pressure to said area overlying said
artery of the subject. The cushion 13 can be inflated with, for
example, air, but other gases and liquids may alternatively be used
to inflate the cushion. The cushion 13 is connected to a unit for
inflating and deflating the cushion, which is not further shown
here. When applying a pressure by means of a cushion to such an
area, the transmission of the pressure to the tissue to be
pressurized is sometimes disturbed by the structure of the area,
which structure comprises bones or tendons lying in the area. The
cushion 13 is provided with a plurality of separately inflatable
cushion parts 14, the cushion parts 14 each applying a local
pressure to the area during operation. The cushion parts 14 enter
between the bones and tendons in the area and the pressure thus is
applied effectively to the tissue between these bones and tendons.
In this embodiment, the cushion parts 14 comprise protuberances 24
projecting from a surface area 15 of the cushion practically
perpendicularly to that surface area 15. The pressure is thus
applied in an effective way by each of the protuberances 24, which
bear a resemblance to fingers applying a pressure to certain
areas.
[0030] FIG. 7 is a perspective view of a measuring unit 2" of a
fifth embodiment of a device according to the invention. In this
embodiment, the carrier 3 comprises an annular body 16 which can be
closed during operation and in which the cushion 13', as described
above for FIG. 6 and provided with a plurality of separately
inflatable cushion parts 14', is provided along an entire inner
wall of said body. This provision of cushion parts 14' along the
inner wall of said body enables the cushion 13' to apply localized
pressure to the entire periphery of the wrist 6 of a subject.
[0031] It is noted that a cushion of the kind as described above,
i.e. a cushion comprising protuberances projecting from a surface
area of the carrier in a direction practically perpendicular to
that surface area, in itself is also usable in other devices for
the monitoring of a vital sign in which the detector for
positioning the measuring unit relative to the artery is not
provided. For example, such a cushion may be used in the blood
pressure monitor known from U.S. Pat. No. 4,660,566, instead of the
flat cushion used therein.
[0032] FIG. 8 is a perspective view of a carrier of a sixth
embodiment of a device according to the invention. In this
embodiment, the carrier 3 comprises a annular body 17 which is
entirely rigid. The annular body 17 may, for example, consist of a
hard plastic, but other materials could alternatively be chosen. In
this way, when a cushion in the device is to be inflated, the
annular body forms a boundary for the level of expansion of the
cushion, and thus prevents excessive expansion of the cushion which
would hamper a good operation of the device. The rigid body 17 can
be given a fixed shape, which may be chosen to fit specific
subjects, so that the device may be adapted to certain specific
user groups, such as children. Furthermore the shape may be adapted
to the specific type of device for monitoring a vital sign in which
it is used.
[0033] It is noted that a carrier of the kind as described above,
i.e. a carrier comprising an annular body which is at least partly
rigid, in itself is also usable in other devices for the monitoring
of a vital sign, in which devices the detector for positioning the
measuring unit relative to the artery is not provided. For example,
such a carrier may be used in the blood pressure monitor known from
U.S. Pat. No. 4,660,566, instead of the flexible band used
therein.
[0034] Besides, a device for monitoring a vital sign which
comprises both a carrier and a cushion as described above, but in
which the detector for positioning the measuring unit relative to
the artery is not provided, is also possible.
[0035] The devices described above are blood pressure monitors. It
is noted that a detector for detecting the position of a measuring
unit relative to an artery of a subject and for actuating a
feedback signal representative of this position, a cushion with
separately inflatable cushion parts, and an at least partly rigid
annular body, may, individually or in any combination with each
other, be advantageously used in other kinds of devices for
monitoring a vital sign such as, for example, pulse oximetry
monitors and heart rate monitors.
* * * * *