Abstrict
The blood pressure monitor (10) comprises an artery pressing section
which locally presses an artery of the extremities or fingers at
an arbitrarily variable pressing force, a vibration sensor (22)
detecting a vibration of the artery at the pressed point or points
on a peripheral side thereof, a mounting mechanism (26) which positions
the artery pressing section and the vibration sensor (22) on the
artery, a blood pressure determination section which determines
the maximum and minimum pressures based on various pressing force
values applied by the above-mentioned artery pressing section and
signals detected by the vibration sensor (22) at these various pressing
force values, guides (34) which are provided on each side of the
vibration sensor (22) and guide the vibration sensor (22) to the
artery by being located on the both sides of the artery, and a peripheral
side pressing section which presses the artery on the peripheral
side from the vibration sensor (22). The blood pressure monitor
(10) does not impart an unpleasant or disagreeable feeling to the
subject.
Claims
What is claimed is:
1. A blood pressure monitor comprising: an artery pressing section
adapted to locally press an artery of any one of extremities and
fingers at an arbitrarily variable pressing force; a control section
which controls the pressing force applied by the artery pressing
section; a vibration sensor for detecting a vibration of the artery
at a point on the peripheral side of the point to be pressed by
the artery pressing section; and a blood pressure determination
section which determines a maximum blood pressure and a minimum
blood pressure based on various pressing force values applied by
the artery pressing section and signals detected by the vibration
sensor at the various pressing force values.
2. The blood pressure monitor according to claim 1, further comprising
a positioning mechanism which positions the artery pressing section
and the vibration sensor on the artery.
3. The blood pressure monitor according to claim 1, further comprising
guides provided on each side of the vibration sensor and guiding
the vibration sensor to the artery by being located on both sides
of the artery.
4. The blood pressure monitor according to claim 1, further comprising
a peripheral side pressing section which presses the artery at a
point peripheral to the vibration sensor and almost completely shuts
off the vibration transmitted by an artery section peripheral to
the vibration sensor.
5. The blood pressure monitor according to claim 1, wherein the
vibration sensor detects the vibration transmitted to the artery
pressing section.
6. The blood pressure monitor according to claim 1, further comprising
a sensor pressing section which causes the vibration sensor to press
the artery.
7. The blood pressure monitor according to claim 1, wherein the
vibration sensor is a pulse wave sensor detecting a pulse waveform,
and wherein the blood pressure monitor further comprises a conversion
section which converts the pulse waveform into a blood pressure
waveform based on the maximum blood pressure and the minimum blood
pressure.
8. The blood pressure monitor according to claim 7, further comprising
a blood-pressure-waveform processing section which calculates at
least one of following items based on the blood pressure waveform
obtained by the conversion section; a mean blood pressure, a pulse
pressure which is a difference between the maximum blood pressure
and the minimum blood pressure, an after-ejection pressure which
is a pressure difference between a dicrotic notch and the maximum
blood pressure, a dicrotic wave height which is a pressure difference
between the dicrotic notch and a dicrotic wave peak, an after-ejection
pressure ratio which is the after-ejection pressure normalized by
the pulse pressure, a dicrotic wave height ratio which is the dicrotic
wave height normalized by the pulse pressure, and a dicrotic wave
height after-ejection pressure ratio which is a ratio of the dicrotic
wave height and the after-ejection pressure.
9. The blood pressure monitor according to claim 1, wherein the
artery pressed by the artery pressing section, of which vibration
is detected by the vibration sensor, is a radial artery.
10. A blood pressure monitor comprising: a first artery pressing
section adapted to locally press a first artery of any one of extremities
and fingers having the first artery and a second artery at an arbitrarily
variable pressing force; a control section which controls the pressing
force applied by the first artery pressing section; a second artery
pressing section adapted to locally press the second artery; a vibration
sensor for detecting a vibration of the first artery at a pressed
point or on a peripheral side thereof; and a blood pressure determination
section which determines a maximum blood pressure and a minimum
blood pressure based on various pressing force values applied by
the first artery pressing section and a signal detected by the vibration
sensor at each of the pressing force values.
11. The blood pressure monitor according to claim 10, further comprising
a positioning mechanism which positions the first artery pressing
section and the vibration sensor on the first artery.
12. The blood pressure monitor according to claim 10, further comprising
guides provided on each side of the vibration sensor and guiding
the vibration sensor to the first artery by being located on both
sides of the first artery.
13. The blood pressure monitor according to claim 10, wherein the
vibration sensor detects the vibration transmitted to the first
artery pressing section.
14. The blood pressure monitor according to claim 10, further comprising
a sensor pressing section which causes the vibration sensor to press
the first artery.
15. The blood pressure monitor according to claim 10, wherein the
first artery pressed by the first artery pressing section, of which
vibration is detected by the vibration sensor, is a radial artery.
16. The blood pressure monitor according to claim 10, wherein the
vibration sensor is a pulse wave sensor detecting a pulse waveform,
and wherein the blood pressure monitor further comprises a conversion
section which converts the pulse waveforms into a blood pressure
waveform based on the maximum blood pressure and the minimum blood
pressure.
17. The blood pressure monitor according to claim 16, further comprising
a blood-pressure-waveform processing section which calculates at
least one of following items based on the blood pressure waveform
obtained by the conversion section: a mean blood pressure, a pulse
pressure which is a difference between the maximum blood pressure
and the minimum blood pressure, a after-ejection pressure which
is a pressure difference between a dicrotic notch and the maximum
blood pressure, a dicrotic wave height which is a pressure difference
between the dicrotic notch and a dicrotic wave peak, an after-ejection
pressure ratio which is the after-ejection pressure normalized by
the pulse pressure, a dicrotic wave height ratio which is the dicrotic
wave height normalized by the pulse pressure, and a dicrotic wave
height after-ejection pressure ratio which is a ratio of the dicrotic
wave height and the after-ejection pressure.
18. A pulse wave detection apparatus comprising: an artery pressing
section adapted to locally press an artery of any one of extremities
and fingers at an arbitrarily variable pressing force; a control
section which controls the pressing force applied by the artery
pressing section; and a pulse sensor for detecting a pulse of the
artery at a peripheral side from where the artery pressing section
is to press.
19. The pulse wave detection apparatus according to claim 18, further
comprising a positioning mechanism which positions the artery pressing
section and the pulse sensor on the artery.
20. The pulse wave detection apparatus according to claim 18, further
comprising guides provided on each side of the pulse sensor and
guiding the pulse sensor to the artery by being located on both
sides of the artery.
21. The pulse wave detection apparatus according to claim 18, wherein
the pulse sensor detects the vibration transmitted to the artery
pressing section.
22. The pulse wave detection apparatus according to claim 18, further
comprising a sensor pressing section which causes the pulse sensor
to press the artery.
23. The pulse wave detection apparatus according to claim 18, wherein
the artery pressed by the artery pressing section, of which pulse
is detected by the pulse sensor, is a radial artery.
24. A pulse wave detection apparatus comprising: an artery pressing
section adapted to locally press an artery of any one of extremities
and fingers at an arbitrarily variable pressing force; a control
section which controls the pressing force applied by the artery
pressing section; a pulse sensor for detecting a pulse of the artery
at a pressed point or on a peripheral side thereof; and a pressure
waveform processing section which calculates at least one of the
following items based on the pulse waveform obtained by the pulse
sensor: an after-ejection pressure ratio which is a after-ejection
pressure normalized by a pulse pressure, the after-ejection pressure
being a pressure difference between a dicrotic notch and a maximum
blood pressure, the pulse pressure being a difference between the
maximum blood pressure and a minimum blood pressure; a dicrotic
notch difference ratio which is a dicrotic notch difference normalized
by the pulse pressure, the dicrotic notch difference being a difference
between a blood pressure of the dicrotic notch and the minimum blood
pressure; a mean-blood-pressure pulse-pressure ratio which is a
ratio of the mean-blood-pressure and the pulse pressure, a dicrotic
wave height ratio which is a dicrotic wave height normalized by
the pulse pressure; and a dicrotic-wave-height after-ejection pressure
ratio which is a ratio of the dicrotic wave height and the after-ejection
pressure.
25. A blood pressure monitor comprising: a band adapted to be wound
around any one of extremities and fingers having a first artery
and a second artery; a pressure applying section which is installed
on a inner surface of the band and is adapted to apply a variable
pressure to the first artery by changing a volume of a fluid included
therein; a second artery pressing section which is attached to the
pressure applying section and is adapted to locally press the second
artery; a control section which controls the pressure applied by
the pressure applying section; a pressure sensor which detects a
vibration of the artery transmitted as a pressure change of the
fluid via the pressure applying section; and a blood pressure determination
section which determines a maximum blood pressure and a minimum
blood pressure based on various pressing force values applied by
the pressure applying section and a signal detected by the pressure
sensor at each of the pressing force values.
26. A blood pressure monitor comprising: a band adapted to be wound
around any one of extremities and fingers having a first artery
and a second artery; a first artery pressing section which is installed
on a inner surface of the band and is adapted to locally apply a
variable pressing force to the first artery by changing a volume
of a fluid included therein; a second artery pressing section which
is installed on a inner surface of the band and is adapted to locally
apply a variable pressing force to the second artery by changing
a volume of a fluid included therein; a control section which controls
the pressing force applied by the first artery pressing section;
a pressure sensor which detects a vibration of the artery transmitted
as a pressure change of the fluid via the first artery pressing
section; and a blood pressure determination section which determines
a maximum blood pressure and a minimum blood pressure based on various
pressing force values applied by the first artery pressing section
and a signal detected by the pressure sensor at each of the pressing
force values.
27. A blood pressure monitor comprising: an artery pressing section
adapted to press an artery of any one of extremities or fingers
at an arbitrarily variable pressing force; a control section which
controls the pressing force applied to the artery by the artery
pressing section so as to gradually increase the pressing force
from a predetermined minimum pressing force; a pressure sensor detecting
a vibration of the artery at a point on the peripheral side of the
point to be pressed by the artery pressing section; and a blood
pressure determination section which determines a maximum blood
pressure and a minimum blood pressure based on various pressing
force values applied by the artery pressing section and a signal
detected by the pressure sensor at each of the pressing force values.
28. The blood pressure monitor according to claim 27, further comprising
a conversion section which converts a signal detected by the pressure
sensor into a blood pressure waveform based on the maximum blood
pressure and the minimum blood pressure.
29. The blood pressure monitor according to claim 28, further comprising
a blood-pressure-waveform processing section which calculates at
least one of following items based on the blood pressure waveform
obtained by the conversion section: a mean blood pressure, a pulse
pressure which is a difference between the maximum blood pressure
and the minimum blood pressure, a after-ejection pressure which
is a pressure difference between a dicrotic notch and the maximum
blood pressure, a dicrotic wave height which is a pressure difference
between the dicrotic notch and a dicrotic wave peak, an after-ejection
pressure ratio which is the after-ejection pressure normalized by
the pulse pressure, a dicrotic wave height ratio which is the dicrotic
wave height normalized by the pulse pressure, and a dicrotic wave
height after-ejection pressure ratio which is a ratio of the dicrotic
wave height and the after-ejection pressure.
Description TECHNICAL FIELD
The present invention relates to a blood pressure monitor and pulse
wave detection apparatus.
BACKGROUND OF THE ART
Blood pressure is commonly measured by auscultation which consists
of applying a pressing force greater than the maximum blood pressure
to the artery by pressing the brachium or wrist around the circumference
and detecting a vibration of the pressed artery on the peripheral
side, while gradually decreasing the pressing force.
A blood pressure monitor disclosed in Japanese Patent No. 2804484,
for example, has a means of detecting displacement of the cuff for
applying pressure around the wrist.
Japanese Patent Application Laid-open No. 5-300885 discloses a
blood pressure monitor designed as shown in FIG. 2 of the published
document, wherein the arterial blood flow is controlled by the pressing
force applied to the arm by altering the degree of expansion of
an air bag 7 which consists of section of a cuff wound around the
arm. This pressing force is monitored by a third pressure sensor
1, which latches the pressing force when a first pressure sensor
2 detects the maximum arterial pulse wave and the pressing force
when a second pressure sensor 3 detects an arterial pulse wave above
a prescribed level. The peripheral blood pressure is determined
based on the latched pressure information.
In these blood pressure measuring methods, however, almost the
entire circumference of the brachium or wrist is pressed so that
the nervous tissues which are distributed densely close to funny
bones in the case of the wrist, for instance, are pressed, imparting
an unpleasant and disagreeable feeling. Such an unpleasant and disagreeable
feeling caused by pressing the entire circumference of the measuring
section such as the extremities and fingers has been experienced
when the blood pressure is measured by pressing the entire circumference
of other parts such as brachium and fingers.
DISCLOSURE OF THE INVENTION
The present invention has been completed in view of this situation
and has an object of providing a blood pressure monitor and a pulse
wave detection apparatus which impart an unpleasant and disagreeable
feeling to a subject only to a minimal degree.
One aspect of the present invention provides a blood pressure monitor
comprising: an artery pressing section which locally presses an
artery of any one of extremities and fingers at an arbitrarily variable
pressing force; a control section which controls the pressing force
applied by the artery pressing section; a vibration sensor detecting
a vibration of the artery at a point pressed by the artery pressing
section or at a point peripheral to the point pressed by the artery
pressing section; and a blood pressure determination section which
determines a maximum blood pressure and a minimum blood pressure
based on various pressing force values applied by the artery pressing
section and signals detected by the vibration sensor at the various
pressing force values.
In this blood pressure monitor, the blood pressure determination
section determines the maximum and minimum pressures based on various
pressing force values applied when the artery pressing section locally
presses an artery of the extremities or fingers and the signals
detected by the vibration sensor at these various pressing force
values. Because the extremities or fingers are not pressed over
the entire circumference, no discomfort or unfavorable feeling will
be imparted to the subject.
In addition, because the artery pressing section presses the artery
only locally, the pressing operation will not be interfered with
by the sinews or bones which may be present close to the artery.
Therefore, the pressing operation can press the artery with certainty,
ensuring measurement of the blood pressure more accurately than
in the conventional method in which the entire circumference of
the extremities or fingers is pressed by a cuff or the like.
Another aspect of the present invention provides a blood pressure
monitor comprising: a first artery pressing section which locally
presses a first artery of any one of extremities and fingers having
the first artery and a second artery at an arbitrarily variable
pressing force; a control section which controls the pressing force
applied by the first artery pressing section; a second artery pressing
section which locally presses the second artery; a vibration sensor
detecting a vibration of the first artery at a pressed point or
on a peripheral side thereof; and a blood pressure determination
section which determines a maximum blood pressure and a minimum
blood pressure based on various pressing force values applied by
the first artery pressing section and a signal detected by the vibration
sensor at each of the pressing force values.
In this blood pressure monitor, the blood pressure determination
section determines the maximum and minimum pressures based on various
pressing force values applied when the first artery pressing section
locally presses an artery of the extremities or fingers and the
signals detected by the vibration sensor at these various pressing
force values. Because the extremities or fingers are not pressed
over the entire circumference, no discomfort or unfavorable feeling
will be imparted to the subject.
In addition, because this blood pressure monitor is equipped with
the second artery pressing section which locally presses the second
artery, the monitor can shut off the blood flow to the peripheral
side from the pressed point. Therefore, the vibration of the first
artery detected by the vibration sensor will not be affected by
the pulses due to the blood flowing from the second artery via the
artery which connect the second and first arteries, thereby ensuring
more accurate blood pressure measurement.
The above-mentioned blood pressure monitor may further comprise
a positioning mechanism which positions the first pressing section
and the vibration sensor on the artery.
Such a positioning mechanism ensures easy determination of positioning
for the artery pressing section and the vibration sensor on the
artery.
The above-mentioned blood pressure monitor may further comprise
guides provided on each side of the vibration sensor and guiding
the vibration sensor to the artery by being located on both sides
of the artery.
This configuration ensures easy and certain positioning of the
vibration sensor on the artery by causing the guides which guide
the vibration sensor on the artery to be located on each side of
the artery.
The above-mentioned blood pressure monitor may further comprise
a peripheral side pressing section which presses the artery at a
point peripheral to the vibration sensor and almost completely shuts
off the vibration transmitted by an artery section peripheral to
the vibration sensor.
According to this configuration, because the artery is pressed
by the peripheral side pressing section on the peripheral side from
the artery pressing section and the vibration sensor, pulses transmitted
from branch passages of arteries or the like can be shut off, enabling
mere accurate blood pressure measurement.
In the above-mentioned blood pressure monitor, it is preferable
that the vibration sensor detects the vibration transmitted to the
artery pressing section.
The blood pressure can be measured without causing the oscillatory
sensor to directly come into contact with the skin.
The above-mentioned blood pressure monitor may further comprise
a sensor pressing section which causes the vibration sensor to press
the artery.
This configuration, which enables the sensor pressing section of
the vibration sensor to press the artery, causes the vibration sensor
to press the artery at an appropriate pressure so that a vibration
from the artery can be detected with certainty.
In the above-mentioned blood pressure monitor, the vibration sensor
may be a pulse wave sensor detecting a pulse waveform, and the blood
pressure monitor may further comprise a conversion section which
converts the pulse waveform into a blood pressure waveform based
on the maximum blood pressure and the minimum blood pressure.
In this blood pressure monitor, the conversion section converts
the pulse waveforms obtained from a pulse wave detection apparatus
located on the artery into blood pressure waveforms based on the
maximum and minimum blood pressures measured by the blood pressure
monitor, thereby obtaining blood pressure waveforms. Therefore,
blood pressure waveforms can be obtained non-invasively.
The above-mentioned blood pressure monitor may further comprise
a blood-pressure-waveform processing section which calculates at
least one of following items based on the blood pressure waveform
obtained by the conversion section; a mean blood pressure, a pulse
pressure which is a difference between the maximum blood pressure
and the minimum blood pressure, a after-ejection pressure which
is a pressure difference between a dicrotic notch and the maximum
blood pressure, a dicrotic wave height which is a pressure difference
between the dicrotic notch and a dicrotic wave peak, an after-ejection
pressure ratio which is the after-ejection pressure normalized by
the pulse pressure, a dicrotic wave height ratio which is the dicrotic
wave height normalized by the pulse pressure, and a dicrotic wave
height after-ejection pressure ratio which is a ratio of the dicrotic
wave height and the after-ejection pressure.
In this manner, at least one of the mean blood pressure, pulse
pressure which is the difference between the maximum and minimum
blood pressures, after-ejection pressure which is the pressure difference
between a dicrotic notch and the maximum blood pressure, dicrotic
wave height which is the pressure difference between the dicrotic
notch and the dicrotic wave peak, after-ejection pressure ratio
which is the after-ejection pressure normalized by the pulse pressure,
and dicrotic wave height after-ejection pressure ratio which is
a ratio of the dicrotic wave height and the after-ejection pressure
can be calculated by the blood-pressure-waveform processing section.
In the above-mentioned blood pressure monitor, the artery pressed
by the artery pressing section, of which vibration is detected by
the vibration sensor, may be a radial artery.
Because the blood pressure monitor can measure blood pressure without
pressing section of the wrist around the ulna in which many nerve
tissues are present, it is possible to measure the blood pressure
on the wrist without imparting an unpleasant and disagreeable feeling
to a subject.
A pulse wave detection apparatus which is further aspect of the
present invention comprises: an artery pressing section which locally
presses an artery of any one of extremities and fingers at an arbitrarily
variable pressing force; a control section which controls the pressing
force applied by the artery pressing section; and a pulse sensor
detecting pulse of the artery at a pressed point or on a peripheral
side thereof.
In this pulse wave detection apparatus, the pulse wave sensor detects
pulse waves at the point of the artery pressing section or on the
peripheral side based on variable pressing force values applied
when the artery pressing section locally presses the artery of the
extremities or fingers. Therefore, pulse waves at various pressures
applied by the artery pressing section can be detected.
The above-mentioned pulse wave detection apparatus may further
comprise a positioning mechanism which positions the artery pressing
section and the pulse sensor on the artery.
Such a positioning mechanism ensures easy determination of positioning
for the artery pressing section and the vibration sensor on the
artery.
The above-mentioned pulse wave detection apparatus may further
comprise guides provided on each side of the pulse sensor and guiding
the pulse sensor to the artery by being located on both sides of
the artery.
This configuration ensures easy and certain positioning of the
pulse detector on the artery by causing the guides which guide the
pulse detector on the artery to be located on each side of the artery.
In the above-mentioned pulse wave detection apparatus, the pulse
sensor may detect the vibration transmitted to the artery pressing
section.
This configuration enables the pulse detector to detect pulse waves
without applying pressure to the artery from above the skin.
The above-mentioned pulse wave detection apparatus may further
comprise a sensor pressing section which causes the pulse sensor
to press the artery.
This configuration, which enables the sensor pressing section of
the pulse detector to press the artery, causes the pulse detector
to press the artery at an appropriate pressure so that pulses from
the artery can be detected with certainty.
In the above-mentioned pulse wave detection apparatus, the artery
pressed by the artery pressing section, of which pulse is detected
by the pulse sensor, may be a radial artery.
Therefore, pulse waves from the radial artery at various pressures
applied by the artery pressing section can be detected
The above-mentioned pulse wave detection apparatus may further
comprise: a pressure waveform processing section which calculates
at least one of the following items based on the pulse waveform
obtained by the pulse sensor: an after-ejection pressure ratio which
is an after-ejection pressure normalized by a pulse pressure, the
after-ejection pressure being a pressure difference between a dicrotic
notch and a maximum blood pressure, the pulse pressure being a difference
between the maximum blood pressure and a minimum blood pressure;
a dicrotic notch difference ratio which is a dicrotic notch difference
normalized by the pulse pressure, the dicrotic notch difference
being a difference between a blood pressure of the dicrotic notch
and the minimum blood pressure; a mean-blood-pressure pulse-pressure
ratio which is a ratio of the mean-blood-pressure and the pulse
pressure, a dicrotic wave height ratio which is a dicrotic wave
height normalized by the pulse pressure; and a dicrotic-wave-height
after-ejection pressure ratio which is a ratio of the dicrotic wave
height and the after-ejection pressure.
A still further aspect of the present invention provides a blood
pressure monitor comprising: a band wound around any one of extremities
and fingers; a pressure applying section which is installed on a
inner surface of the band and applies a variable pressure around
any one of the extremities and fingers by changing a volume of a
fluid included therein; an artery pressing section which is attached
to the pressure applying section and locally presses an artery of
any one of the extremities and fingers; a control section which
controls a pressing force applied to the artery by the artery pressing
section by changing the pressure applied by the pressure applying
section; a pressure sensor which detects a vibration of the artery
transmitted as a pressure change of the fluid, the vibration transmitted
to the fluid via the artery pressing section and the pressure applying
section; and a blood pressure determination section which determines
a maximum blood pressure and a minimum blood pressure based on various
pressing force values applied by the artery pressing section and
a signal detected by the pressure sensor at each of the pressing
force values.
In this blood pressure monitor, the artery pressing section installed
in the pressure applying section located inside the band locally
presses the artery at various pressures. The blood pressure determination
section determines the maximum and minimum pressures based on the
various pressing force values applied and the signals detected by
the pressure sensor at these various pressing force values. Therefore,
the artery is pressed by the artery pressing section at a sufficient
pressure so that the region in which the pressure applying section
or the band come into contact may not become so large. As a result,
a pressure sufficiently great as to impart an unpleasant or disagreeable
feeling to the subject will not be applied.
In addition, because the artery pressing section presses the artery
only locally, the pressing operation will not be interfered with
by the sinews or bones which may be present close to the artery.
Therefore, the pressing operation can press the artery with certainty,
ensuring measurement of the blood pressure more accurately than
in the conventional method in which the artery is directly pressed
by a cuff or the like applied to the circumference of the extremities
or fingers Thus, more accurate blood pressure measurement can be
ensured.
A still further aspect of the present invention provides a blood
pressure monitor comprising: a band wound around any one of extremities
and fingers having a first artery and a second artery; a pressure
applying section which is installed on a inner surface of the band
and applies a variable pressing force to the first artery by changing
a volume of a fluid included therein; a second artery pressing section
which is attached to the pressure applying section and locally presses
the second artery; a control section which controls the pressure
applied by the pressure applying section; a pressure sensor which
detects a vibration of the artery transmitted as a pressure change
of the fluid via the pressure applying section; and a blood pressure
determination section which determines a maximum blood pressure
and a minimum blood pressure based on various pressing force values
applied by the pressure applying section and a signal detected by
the pressure sensor at each of the pressing force values.
Because this blood pressure monitor is equipped with the second
artery pressing section which locally presses the second artery,
the monitor can shut off the blood flow to the peripheral side from
the pressed point. Therefore, the signals from the first artery
detected by the pressure sensor will not be affected by the pulses
due to the blood flowing from the second artery via the artery which
connect the second and first arteries, thereby ensuring more accurate
blood pressure measurement.
In addition, because the second artery pressing section locally
presses the second artery, there will be no risk of nerves or the
like around the second artery being strongly pressed, thus minimizing
any unpleasant or disagreeable feeling imparted to the subject.
A still further aspect of the present invention provides a blood
pressure monitor comprising: a band wound around any one of extremities
and fingers having a first artery and a second artery; a first artery
pressing section which is installed on a inner surface of the band
and locally applies a variable pressing force to the first artery
by changing a volume of a fluid included therein; a second artery
pressing section which is installed on a inner surface of the band
and locally applies a variable pressing force to the second artery
by changing a volume of a fluid included therein;
a control section which controls the pressing force applied by
the first artery pressing section; a pressure sensor which detects
a vibration of the artery transmitted as a pressure change of the
fluid via the first artery pressing section; and a blood pressure
determination section which determines a maximum blood pressure
and a minimum blood pressure based on various pressing force values
applied by the first artery pressing section and a signal detected
by the pressure sensor at each of the pressing force values.
In this blood pressure monitor, the first artery pressing section
installed in the band locally presses the first artery at various
pressures. The blood pressure determination section determines the
maximum and minimum pressures based on the various pressing force
values applied and the signals detected by the pressure sensor at
these various pressing force values. Because the extremities or
fingers are not pressed over the entire circumference by the first
artery pressing section, no discomfort or unfavorable feeling will
be imparted to the subject.
In addition, because this blood pressure monitor is equipped with
the second artery pressing section which locally presses the second
artery, the monitor can shut off the blood flow to the peripheral
side from the pressed point. Therefore, the vibration from the first
artery detected by the pressure sensor will not be affected by the
pulses due to the blood flowing from the second artery via the artery
which connect the second and first arteries, thereby ensuring more
accurate blood pressure measurement.
A still further aspect of the present invention provides a blood
pressure monitor comprising: an artery pressing section which presses
an artery of any one of extremities or fingers at an arbitrarily
variable pressing force; a control section which controls the pressing
force applied to the artery by the artery pressing section so as
to gradually increase the pressing force from a predetermined minimum
pressing force; a pressure sensor detecting a vibration of the artery
at a point pressed by the artery pressing section or at a point
peripheral to the point pressed by the artery pressing section;
and a blood pressure determination section which determines a maximum
blood pressure and a minimum blood pressure based on various pressing
force values applied by the artery pressing section and a signal
detected by the pressure sensor at each of the pressing force values.
According to this blood pressure monitor, the control section controls
the pressure applied to the artery by the artery pressing section
so that this pressure may be gradually increased from the prescribed
minimum pressure. The blood pressure is measured based on the signals
detected by the pressure sensor and the pressure applied at the
point of measurement. The blood pressure is determined according
to the same principle of the auscultation method using this blood
pressure monitor. Specifically, a vibration of blood vessel walls
due to blood flowing through the blood vessel constricted by the
pressure applied on the peripheral side of the artery is monitored
while changing the pressure applied by the artery. The blood pressure
is then determined from the highest pressure of the artery pressing
section detected by the vibration sensor which detects a vibration
of the blood flowing through the constricted blood vessels as the
maximum blood pressure, and the lowest pressure of the artery pressing
section detected by the vibration sensor which detects a vibration
of the blood flowing through the constricted blood vessels as the
minimum blood pressure. In the blood pressure measurement using
this blood pressure monitor, because the pressure applied by the
pressure applying section is gradually increased starting from a
pressure lower than the conceivable lowest pressure (the prescribed
minimum value), the pressure measurement operation is completed
when the pressure of the artery pressing section becomes almost
equivalent to a pressure corresponding the maximum pressure. Therefore,
the maximum pressure applied to the artery pressing section can
be decreased using this blood pressure monitor as compared with
conventional blood pressure monitors in which a pressure higher
than the conceivable maximum pressure is first applied and then
gradually decreased. As a result, a pressure sufficiently great
as to impart an unpleasant or disagreeable feeling to the subject
will not be applied.
The above-mentioned blood pressure monitor may further comprise
a conversion section which converts a signal detected by the pressure
sensor into a blood pressure waveform based on the maximum blood
pressure and the minimum blood pressure.
In the blood pressure monitor, the blood pressure waveforms can
be obtained from the conversion section which converts the signals
detected by the pressure sensor based on the maximum and minimum
blood pressure. Therefore, blood pressure waveforms can be obtained
non-invasively.
The above-mentioned blood pressure monitor may further comprise
a blood-pressure-waveform processing section which calculates at
least one of following items based on the blood pressure waveform
obtained by the conversion section: a mean blood pressure, a pulse
pressure which is a difference between the maximum blood pressure
and the minimum blood pressure, an after-ejection pressure which
is a pressure difference between a dicrotic notch and the maximum
blood pressure, a dicrotic wave height which is a pressure difference
between the dicrotic notch and a dicrotic wave peak, an after-ejection
pressure ratio which is the after-ejection pressure normalized by
the pulse pressure, a dicrotic wave height ratio which is the dicrotic
wave height normalized by the pulse pressure, and a dicrotic wave
height after-ejection pressure ratio which is a ratio of the dicrotic
wave height and the after-ejection pressure.
In this manner, at least one of the mean blood pressure, pulse
pressure which is the difference between the maximum and minimum
blood pressures, after-ejection pressure which is the pressure difference
between a dicrotic notch and the maximum blood pressure, dicrotic
wave height which is the pressure difference between the dicrotic
notch and the dicrotic wave peak, after-ejection pressure ratio
which is the after-ejection pressure normalized by the pulse pressure,
and dicrotic wave height after-ejection pressure ratio which is
a ratio of the is dicrotic wave height and the after-ejection pressure
can be calculated by the blood-pressure-waveform processing section.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an oblique view showing blood pressure measurement using
the blood pressure monitor of one embodiment of the present invention.
FIG. 2 is a cross-sectional view along the plane B in FIG. 1.
FIG. 3 is a longitudinal sectional view along the line C--C in
FIG. 2.
FIG. 4 is a block diagram showing the electric configuration of
the blood pressure monitor of the first embodiment.
FIG. 5 is a longitudinal sectional view showing a modification
of the first embodiment.
FIG. 6 is a longitudinal sectional view showing another modification
of the first embodiment.
FIG. 7 is a longitudinal sectional view showing still another modification
of the first embodiment.
FIG. 8 is a longitudinal sectional view showing still another modification
of the first embodiment.
FIG. 9 is a perspective view of the modification shown in FIG.
8.
FIG. 10 is a longitudinal sectional view showing still another
modification of the first embodiment.
FIG. 11 is a longitudinal sectional view showing still another
modification of the first embodiment.
FIG. 12 is a block diagram showing the electric configuration of
the blood pressure monitor of a second embodiment.
FIG. 13 is a graph showing a typical blood pressure waveform.
FIG. 14 is a cross-sectional view showing blood pressure measurement
using the blood pressure monitor of a third embodiment of the present
invention.
FIG. 15 is a block diagram showing the electric configuration of
the blood pressure monitor of the third embodiment.
FIG. 16 is a block diagram showing a modification of the electric
configuration of the blood pressure monitor of the third embodiment.
FIG. 17 is a block diagram showing the electric configuration of
the pulse wave detection apparatus of a fourth embodiment.
FIG. 18 is a schematic view showing blood pressure measurement
using the blood pressure monitor of a fifth embodiment worn on the
wrist.
FIG. 19 is a block diagram showing the electric configuration of
the blood pressure monitor of the fifth embodiment.
FIG. 20 is a schematic view showing blood pressure measurement
using the blood pressure monitor of a sixth embodiment worn on the
wrist.
FIG. 21 is a schematic view showing blood pressure measurement
using the blood pressure monitor of a seven embodiment worn on the
wrist.
FIG. 22 is a block diagram showing the electric configuration of
the blood pressure monitor of the seventh embodiment.
FIG. 23 is a schematic view showing blood pressure measurement
using the blood pressure monitor of an eighth embodiment worn on
the wrist.
FIG. 24 is a graph schematically showing the relationship between
the pressure applied by a pressure applying section and signals
detected by a pressure sensor.
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of the present invention is specifically
described below referring to the drawings.
1. First Embodiment
1.1 Configuration of Blood Pressure Monitor
FIG. 1 is an oblique view showing blood pressure measurement using
the blood pressure monitor 10 of this embodiment. FIG. 2 is a cross-sectional
view along the plane B in FIG. 1. FIG. 3 is a longitudinal sectional
view along the line C--C in FIG. 2.
As shown in these figures, the blood pressure monitor 10 of this
embodiment is equipped with a mounting mechanism 26 which determines
positions for a vibration sensor 22, which detects pulses from the
radial artery 94 in the wrist as sound or vibration, and the like,
above the radial artery 94. The mounting mechanism 26 has a square
configuration with one side open and has an upper side 27 capable
of sliding up and down, driven by a driving mechanism not shown
in the drawing. The upper side 27 has a slide block 28 on the back
thereof which is secured movably along the longitudinal direction
of the upper side 27, driven by a driving mechanism not shown in
the drawing The mounting mechanism 26 is configured so as not to
press all around the wrist, particularly not to come into contact
with the ulnar artery 96 in which the many nerve tissues are present
and which therefore tends to impart a disagreeable feeling if pressed.
As shown in FIG. 2 and FIG. 3, under the slide block 28 there are
provided an artery pressing section 14, guides 34, and a vibration
sensor 22 on the top of a sensor pressing section 42.
As shown in FIG. 3, the artery pressing section 14 locally presses
the radial artery 94 from above the radial artery 94 on the proximal
side from the vibration sensor 22. The pressure applied by the artery
pressing section 14 is arbitrarily variable. The pressure applied
by the artery pressing section 14 is a pressure securely set by
feed-back using a pressure sensor which is incorporated as part
of the artery pressing section. Blood flow to the peripheral side
of the radial artery 94 can be interrupted or restricted by adjusting
the pressure applied by the artery pressing section 14.
The vibration sensor 22 detects mechanical vibration or sound on
the peripheral side or the artery pressing section 14 above the
radial artery 94. For example, a pressure sensor, acceleration sensor,
distortion sensor, or microphone can be used as the vibration sensor
22. It is sufficient for the vibration sensor 22 in this embodiment
to detect the presence or absence of vibration due to pulse.
The sensor pressing section 42 is provided under the slide block
28 and causes the vibration sensor 22 secured on the sensor pressing
section 42 to press the radial artery 94. This pressure can be adjusted
by controlling the control section 18 so that the vibration sensor
22 can detect the vibration conveyed from the radial artery 94 in
an optimum condition.
The guides 34 are provided, one on each side of the vibration sensor
22 as shown in FIG. 2. The vibration sensor 22 is guided along the
radial artery 94 by locating the guides 34 on each side of the radial
artery 94.
FIG. 4 is a block diagram showing the electric configuration of
the blood pressure monitor 10 of this embodiment. As shown in this
Fig., the blood pressure monitor 10 is provided with a control section
18, a blood pressure determination section 30, and a notification
section 62 in addition to the previously described sections. These
sections may be incorporated in a mounting mechanism 26, for instance,
or may be independently formed and electrically connected with the
mounting mechanism 26, vibration sensor 22, and pressing sections
14, 42, etc.
The control section 18 controls the pressure applied to the radial
artery 94 by the artery pressing section 14 so that the artery pressing
section 14 may press the radial artery 94 at various pressures in
a prescribed range. The control section 18 also controls the pressure
applied to the vibration sensor 22 by the sensor pressing section
42. The control section 18 further controls positioning by the mounting
mechanism 26. The control section 18 comprises, for example, a CPU
and a memory which stores a program for operating the CPU.
The blood pressure determination section 30 takes information on
various pressures applied by the artery pressing section 14 from
the control section 18, and determines the maximum and minimum blood
pressures based on the information regarding the presence or absence
of detected a vibration or the detected signals which are provided
by the vibration sensor 22 at each of these various pressures. The
blood pressure determination section 14 comprises, for example,
a CPU and a memory which stores a program for operating the CPU.
The notification section 62 may comprise a display section which
indicates the blood pressure values determined by the blood pressure
determination section 30 as characters, a graph, or the like, such
as an LCD, CRT, plotter, or printer, for example, or may comprise
a sound creation section which indicates the blood pressure values
by sound, such as a combination of a sound synthesizer and a speaker,
for example.
1.2 Operation of Blood Pressure Monitor
The blood pressure monitor 10 operates as follows, for example,
to measure blood pressure.
The section to be measured, for example, the wrist is placed in
the prescribed position so that the radial artery 94 of the wrist
may be located close to the vibration sensor 22 of the mounting
mechanism 26 and the palmar side of the wrist may face the surface
27 of the mounting mechanism 26.
Next, the surface 27 of the mounting mechanism 26 is caused to
descend so that the vibration sensor 22 comes into contact with
the wrist.
Next, the slide block 28 is moved until the vibration sensor 22
and the artery pressing section 14 come above the radial artery
94. In this instance, these sections can be easily positioned by
causing the guides 34 to be located on each side of the radial artery
94 by utilizing the engagement due to positioning of the radial
artery 94 below these sections.
The pressure of the sensor pressing section 42 is adjusted by controlling
the control section 18 so that the radial artery 94 is pressed in
an optimum state for the vibration sensor 22 to detect the vibration
from the radial artery 94.
Next, the pressure applied by the artery pressing section 14 located
over the radial artery 94 is changed to various values by the control
section 18 within the range slightly exceeding the commonly encountered
blood pressure values, for example, in the range from 250 to 20
mmHg.
In each point pressed by the artery pressing section 14, the vibration
sensor 22 located on the peripheral side of the artery pressing
section 14 on the radial artery 94 detects a vibration of the blood
flow which flows through blood vessels constricted by the artery
pressing section 14. The detected signals are monitored. The result
for each pressure by the artery pressing section 14 is stored in
blood pressure determination section 30. Each pressing force value
applied by the artery pressing section 14 is transmitted to the
blood pressure determination section 30 from the control section
18 which controls the pressing force value.
The blood pressure determination section 30 determines the blood
pressure when a sufficient number of pressure samples is obtained
over the above-mentioned range for the artery pressing section 14.
Specifically, the blood pressure determination section 30 determines
the highest pressure of the artery pressing section 14 detected
by the vibration sensor 22 which detects a vibration of the blood
flowing through the constricted blood vessels as the maximum blood
pressure, and the lowest pressure of the artery pressing section
14 detected by the vibration sensor 22 which detects a vibration
of the blood flowing through the constricted blood vessels as the
minimum blood pressure. The principle of blood pressure determination
is the same as in the common auscultation method in which the blood
pressure is determined by monitoring the vibration of the blood
vessel when the blood flows through the vessel which is constricted
by the pressure applied to the brachium on the peripheral side using
a brachium band while changing the pressure in the brachium band.
The information on the maximum and minimum blood pressures thus
determined is transmitted to the notification section 62, and presented
by the notification section 62 as a display such as a numerical
value or a graph, printed characters, or as a voice
1.3 Modification of the First Embodiment
1.3.1 As shown in FIG. 5, which corresponds to the above-described
FIG. 3 and shows a longitudinal sectional view of this modified
embodiment, the blood pressure monitor 10 of this embodiment may
have a peripheral side pressing section 38 provided above the radial
artery 94 on the peripheral side from the vibration sensor 22, in
addition to the artery pressing section 14 which is provided above
the radial artery 94 on the proximal side from the vibration sensor
22. The peripheral side pressing section 38 presses the radial artery
94 prior to or simultaneously with the start of blood pressure measurement
to shut off the pulse reversibly conveyed from the radial artery
94 on the peripheral side of the vibration sensor 22. Therefore,
it is possible to shut off pulses conveyed from branches and the
like of the artery, thus preventing such pulses from affecting the
blood pressure measurement. As a result, accuracy of the blood pressure
measurement can be improved.
1.3.2 As shown in FIG. 6, which corresponds to the above-described
FIG. 3 and shows a longitudinal sectional view of this modified
embodiment, the blood pressure monitor 10 of this embodiment may
have the artery pressing section 14 provided on the vibration sensor
22, which presses the radial artery 94 to enable the vibration sensor
22 to detect the vibration transmitted via the artery pressing section
14. In this case, it is unnecessary to provide the sensor pressing
section 42 between the vibration sensor 22 and the slide block 28.
In addition, the guides 34 have a height almost equivalent the total
lengths of the vibration sensor 22 and the sensor pressing section
42, with one guide 34 being located on each side of the vibration
sensor 22 and the artery pressing section 14. According to this
modified embodiment, the blood pressure can be measured without
causing the oscillatory sensor 22 to directly come into contact
with the skin above the radial artery.
1.3.3 The mounting mechanism as a positioning mechanism is not
necessarily the one having the above-mentioned structure, but may
be of the structure shown by the cross section view in FIG. 7, for
example. This mounting mechanism 64 is provided with two frame members
65, two vinculum-shaped members 66 which connect the frame members
65 so that the distance between them may be freely adjusted, and
a sliding block 68 provided on one of the frame members 65 slidably
driven by a drive mechanism which is not shown in the figure The
vinculum-shaped members 66 may be secured to the frame members 65
by screws 67 to provide an appropriate space between the frame members
65. The mounting mechanism 64 is configured so as not to press all
around the wrist, particularly not to come into contact with the
ulnar artery in which many nerve tissues are present and which therefore
tends to impart a disagreeable feeling if pressed. In the same manner
as in the previously described embodiment, a vibration sensor 22,
an artery pressing section 14 (not shown), guides 34, a sensor pressing
section 42, and the like are provided on the slide block 68. The
mounting mechanism 64 of this structure allows continuous measurement
of the blood pressure while the subject is moving because the mounting
mechanism 64 is portable if attached to the wrist or the like.
1.3.4 A mounting mechanism as a positioning mechanism may be configured
as shown in a cross section view in FIG. 8 and a perspective view
in FIG. 9. This mounting mechanism 110 is provided with two frame
members 112 and 113 which are flexurally connected at a joining
section 115, a cloth member 117 which adjusts the flexural conditions
and connects the frame members 112 and 113 so as to maintain the
adjusted flexural conditions, and a slide block 119 provided on
one of the frame members 112 slidably driven by a drive mechanism
which is not shown in the figure. As shown in FIG. 8, the mounting
mechanism 110 is configured so as not to press all around the wrist,
particularly not to come into contact with the ulnar artery in which
many nerve tissues are present and which therefore tends to impart
a disagreeable feeling if pressed. In the same manner as in the
previously described embodiments, a vibration sensor 22, an artery
pressing section 14 (not shown), guides 34, a sensor pressing section
42, and the like are provided on the slide block 119. The mounting
mechanism 110 of this structure also allows continuous measurement
of blood pressure while the subject is moving because the mounting
mechanism is portable if attached to the wrist or the like.
1.3.5 Furthermore, a mounting mechanism as a positioning mechanism
may be configured as shown in a cross section view in FIG. 10. This
mounting mechanism 140 is almost the same as those shown in FIGS.
8 and 9, except that this mounting mechanism has no cloth member
117 which connects the frame members 112 and 113. In addition, this
mounting mechanism 140 has an air bag 142, expandable by a gas such
as air, provided around the frame members 112 and 113, and a band
144 which encloses the air bag 142. If air is filled in the air
bag 142 enclosed by the band 144, the air bag provides pressure
to the frame members 112 and 113 which causes these members to bend.
This mounting mechanism 140 also has a slide block 119 provided
on the frame member 112 slidably driven by a drive mechanism which
is not shown in the figure. The mounting mechanism 140 is configured
so as not to press all around the wrist, particularly not to come
into contact with the ulnar artery 96 in which many nerve tissues
are present and which therefore tends to impart a disagreeable feeling
if pressed. In the same manner as in the previously described embodiments,
a vibration sensor 22, an artery pressing section 14 (not shown),
guides 34, a sensor press section 42, and the like are provided
on the slide block 119. The mounting mechanism 140 of this structure
also allows continuous measurement of blood pressure while the subject
is moving because the mounting mechanism is portable if attached
to the wrist or the like.
1.3.6 Moreover, a mounting mechanism as a positioning mechanism
may be configured as shown in a cross section view in FIG. 11. This
mounting mechanism 170 is almost the same as those shown in FIGS.
8 and 9, except that this mounting mechanism has no cloth member
117 which connects the frame members 112 and 113 The mounting mechanism
170 is further provided with a clock-shaped member 172 around the
circumference of the frame members 112 and 113. The clock-shaped
member 172 has a main body 174, a belt 176, and a clamp 178, with
the main body 174 being secured to the frame member 113. If the
clock-shaped member 172 is fastened by the belt 176 and the belt
176 is clamped by the clamp 178, the clock-shaped member 172 can
apply pressure to the frame members 112 and 113 so as to bend these
members. The main body section 174 may house the above-mentioned
control section 18, blood pressure determination section 30, notification
section 62, and the like. The electric wiring connecting the main
body 174 and the vibration sensor 22, artery pressing section 14,
sensor pressing section 42, and the like which are provided on the
slide block 119 is omitted from FIG. 11. This mounting mechanism
170 also has a slide block 119 provided on one of the frame members
112 slidably driven by a drive mechanism which is not shown in the
figure. As shown in FIG. 11, the mounting mechanism 170 is configured
so as not to press all around the wrist, particularly not to come
into contact with the ulnar artery in which many nerve tissues are
present and which therefore tends to impart a disagreeable feeling
if pressed. In the same manner as in the previously described embodiments,
a vibration sensor 22, an artery pressing section 14 (not shown),
guides 34, a sensor press section 42, and the like are provided
on the slide block 119. The mounting mechanism 170 of this structure
also allows continuous measurement of blood pressure while the subject
is moving because the mounting mechanism 64 is portable if attached
to the wrist or the like.
1.3.7 In the above-mentioned embodiments, the radial artery 94
was taken as an example of artery to be pressed by the artery pressing
section 14 for detection of a vibration using the vibration sensor
22. However, the artery pressed by the artery pressing section 14
for detection of a vibration using the vibration sensor 22 is not
limited to the radial artery, but may be any artery in the extremities
and fingers such as the ulnar artery of the wrist, the palmar finger
artery, the brachial artery, the popliteal artery, and the like.
1.4 Effects of the First Embodiment
As described above, in the blood pressure monitor 10 of the present
embodiment, the blood pressure determination section 30 determines
the maximum and minimum pressures based on various pressing force
values applied when the artery pressing section 14 locally presses
an artery of the extremities or fingers, based on the signals which
the vibration sensor detects based on a vibration of the blood flowing
through blood vessels constricted by the artery pressing section
14. Because the extremities or fingers are not pressed over the
entire circumference by the artery pressing section 14, no discomfort
or unfavorable feeling will be imparted to the subject.
In addition, because the blood pressure monitor 10 of this embodiment
is provided with mounting mechanisms 26, 64, 110, 140, 170 as a
positioning mechanism, the artery pressing section 14 and the vibration
sensor 22 can be easily positioned on the artery. Moreover, because
mounting mechanisms 26, 64, 110, 140, 170 are designed so as not
to press over the entire circumference the extremities or fingers,
no discomfort or unfavorable feeling will be imparted to the subject.
Because the blood pressure monitor 10 of this embodiment is provided
with the guides 34 which guide the vibration sensor 22 on the artery
on each side of the artery, it is possible to locate the vibration
sensor on the artery easily and with certainty.
Because the blood pressure monitor 10 is designed so as to cause
the sensor pressing section 42 of the vibration sensor 22 to press
the artery, it is possible for the vibration sensor to press the
artery at an appropriate pressure so that a vibration from the artery
can be detected with certainty.
2. Second Embodiment
The second embodiment differs from the first embodiment in that
this embodiment uses a pulse wave sensor instead of the vibration
sensor, is provided with a conversion section for converting a pulse
wave into a blood pressure waveform, and a blood-pressure-waveform
processing section for introducing various indicators based on the
blood pressure waveform, and has a notification section which can
provide not only information on the maximum and minimum blood pressures,
but also information on the blood pressure waveform converted by
the conversion section and various indicators introduced by the
blood-pressure-waveform processing section. Other features are the
same as in the first embodiment, so description thereof is omitted
corresponding sections in each figure are indicated by the same
symbols as in the first embodiment.
2.1 Configuration of Blood Pressure Monitor
In the same manner as in the first embodiment, the blood pressure
monitor of this embodiment is provided with a mounting mechanism
26 as a positioning mechanism, guides 34, an artery pressing section
14, a peripheral side pressing section 38, a sensor pressing section
42, a control section 18, a blood pressure determination section
30, and a notification section 62.
FIG. 12 is a block diagram showing the electric configuration of
the blood pressure monitor 70 of this embodiment. As shown in this
FIG., the blood pressure monitor 70 is provided with a pulse wave
sensor 46 in place of the vibration sensor 22 of the first embodiment,
and further provided with a conversion section 50 and a blood-pressure-waveform
processing section 54.
The pulse wave sensor 46 detects not only the presence or absence
of a pulse wave due to the flow of blood, but also pulse waveforms
produced by pulse. A pressure sensor, acceleration sensor, distortion
sensor, or microphone, for example, can be used as the pulse wave
sensor 46.
The conversion section 50 converts pulse waveforms detected by
the pulse wave sensor 46 into a blood pressure waveform using the
information on the maximum and minimum blood pressures determined
by the blood pressure determination section 30. The conversion section
50 comprises, for example, a CPU and a memory which stores a program
for operating the CPU. In this manner, the blood pressure monitor
obtains blood pressure waveforms by converting the pulse waveforms
detected by the pulse wave sensor 46 located on the artery into
blood pressure waveforms based on the maximum and minimum blood
pressure measured by the blood pressure monitor. Thus, the instrument
can non-invasively obtain blood pressure waveforms.
FIG. 13 is a graph showing a typical blood pressure waveform obtained
in this manner. As shown in this figure, a blood pressure waveform
of the artery typically has an ejection wave having a highest peak,
a tidal wave having a second highest peak, a dicrotic wave having
a third highest peak, and a dicrotic notch which is a valley between
the tidal wave and dicrotic wave. The peak of the ejection wave
corresponds to the contraction period blood pressure (maximum blood
pressure) BP.sub.eye. Diastolic blood pressure (minimum blood pressure)
BP.sub.dia corresponds to the lowest blood pressure in the blood
pressure waveform. The difference between the contraction period
blood pressure BP.sub.eye and the diastolic blood pressure BP.sub.dia
is called pulse pressure .DELTA.BP. The mean blood pressure BP.sub.mean
is a temporal average of the blood pressure.
Based on the blood pressure waveform obtained by the conversion
section 50, the blood-pressure-waveform processing section 54 calculates
at least one of the following items; a mean blood pressure BP.sub.mean,
a pulse pressure .DELTA.BP which is the difference between the maximum
and minimum blood pressures, an after-ejection pressure .DELTA.BP.sub.P
which is the difference between the dicrotic notch and the maximum
blood pressure, a dicrotic wave height .DELTA.BP.sub.D which is
the difference between the dicrotic notch and the dicrotic wave
peak, an after-ejection pressure ratio .DELTA.BP.sub.P /.DELTA.BP
which is the after-ejection pressure .DELTA.BP.sub.P normalized
by the pulse pressure .DELTA.BP, and a dicrotic wave height after-ejection
pressure ratio .DELTA.BP.sub.D /.DELTA.BP.sub.P which is a ratio
of the dicrotic wave height .DELTA.BP.sub.D and the after-ejection
pressure .DELTA.BP.sub.P.
The conversion section 50 and the blood-pressure-waveform processing
section 54 may be incorporated in a mounting mechanism 26, for instance,
or may be independently formed and electrically connected with the
mounting mechanism 26, pulse wave sensor 46, and pressing sections
14, 42, etc.
The notification section 62 provides not only the information on
the maximum blood pressure BP.sub.eye and the minimum blood pressure
BP.sub.dia, but also the information on blood pressure waveform
converted by the conversion section 50 and various indicators made
available by the blood-pressure-waveform processing section 54,
such as a mean blood pressure BP.sub.mean, pulse pressure .DELTA.BP,
after-ejection pressure .DELTA.BP.sub.P, dicrotic wave height .DELTA.BP.sub.D,
after-ejection pressure ratio .DELTA.BP.sub.P /.DELTA.BP, and dicrotic
wave height after-ejection pressure ratio .DELTA.BP.sub.D /.DELTA.BP.sub.P.
2.2 Operation of Blood Pressure Monitor
The operation of the blood pressure monitor 70 of this embodiment
is the same as the operation of the blood pressure monitor 10 of
the first embodiment up to the point where the blood pressure determination
section determines the blood pressure. After determination of the
blood pressure by the blood pressure determination section 30, the
blood pressure monitor 70 which is provided with a pulse wave sensor
46 in place of the vibration sensor 22 is operated as follows.
The information on the maximum and minimum blood pressures determined
by the blood pressure determination section 30 and the information
on the pulse waveforms detected by the pulse wave sensor 46 are
input into the conversion section 50.
Next, the conversion section 50 converts the pulse waveforms detected
by the pulse wave sensor 46 using the information on the maximum
and minimum blood pressures determined by the blood pressure determination
section 30. (See FIG. 13)
Then, the information on the blood pressure waveform obtained by
the conversion section 50 is input into the blood-pressure-waveform
processing section 54. Based on the blood pressure waveform obtained
by the conversion section 50, the blood-pressure-waveform processing
section 54 calculates at least any one of the following items: a
mean blood pressure BP.sub.mean, a pulse pressure .DELTA.BP which
is the difference between the maximum blood pressure BP.sub.eye
and the minimum blood pressure BP.sub.dia, an after-ejection pressure
.DELTA.BP.sub.P which is the pressure difference between the dicrotic
notch and the maximum blood pressure, a dicrotic wave height .DELTA.BP.sub.D
which is the pressure difference between the dicrotic notch and
the dicrotic wave peak, an after-ejection pressure ratio .DELTA.BP.sub.P
/.DELTA.BP which is the after-ejection pressure .DELTA.BP.sub.P
normalized by the pulse pressure .DELTA.BP, and a dicrotic wave
height after-ejection pressure ratio .DELTA.BP.sub.D /.DELTA.BP.sub.P
which is a ratio of the dicrotic wave height .DELTA.BP.sub.D and
the after-ejection pressure .DELTA.BP.sub.P.
The information on the blood pressure determined by the blood pressure
determination section 30, information on the blood pressure waveform
converted by the conversion section 50, information on various indicators
made available by the blood-pressure-waveform processing section
54, and the like are input to the notification section 62. The notification
section 62 presents the information as a display such as a numerical
value or a graph, printed characters, or as a voice.
2.3 Modification of the Second Embodiment
The modification described for the first embodiment can be applied
also to the second embodiment.
2.4 Effects of the Second Embodiment
As mentioned above, in the blood pressure monitor 70 of this embodiment
the conversion section converts the pulse waveforms obtained from
the pulse wave sensor 46 located on the artery into blood pressure
waveforms based on the maximum and minimum blood pressures which
are non-invasively measured by the blood pressure monitor 70. Therefore,
blood pressure waveforms can be obtained non-invasively
In addition, the blood pressure monitor 70 of this embodiment can
cause the blood-pressure-waveform processing section 54 to make
available at least one of the following items: a mean blood pressure
BP.sub.mean, a pulse pressure .DELTA.BP which is the difference
between the maximum and minimum blood pressures, an after-ejection
pressure .DELTA.BP.sub.P which is the pressure difference between
the dicrotic notch and the maximum blood pressure, a dicrotic wave
.DELTA.BP.sub.D which is the pressure difference between the dicrotic
notch and the dicrotic wave peak, an after-ejection pressure ratio
.DELTA.BP.sub.P /.DELTA.BP which is the after-ejection pressure
.DELTA.BP.sub.P normalized by the pulse pressure .DELTA.BP, and
a dicrotic wave height after-ejection pressure ratio .DELTA.BP.sub.D
/.DELTA.BP.sub.P which is a ratio of the dicrotic wave height .DELTA.BP.sub.D
and the after-ejection pressure .DELTA.BP.sub.P.
3. Third Embodiment
The third embodiment differs from the first embodiment in that
the former blood pressure monitor is provided with a second artery
pressing section. Other features are the same as in the first embodiment,
so description thereof is omitted. Corresponding sections in each
figure are indicated by the same symbols as in the first embodiment.
3.1 Configuration of Blood Pressure Monitor
In the same manner as in the blood pressure monitor 10 of the first
embodiment, the blood pressure monitor 76 of this embodiment is
provided with a mounting mechanisms 26 as a positioning mechanism,
guides 34, an artery pressing section 14 as a first artery pressing
section, a sensor pressing section 42, a control section 18, a blood
pressure determination section 30, and a notification section 62.
FIG. 14, which corresponds to FIG. 2 for the first embodiment,
is a cross section view showing blood pressure measurement using
the blood pressure monitor 76 of this embodiment. FIG. 15 is a block
diagram showing the electric configuration of the blood pressure
monitor 76 of this embodiment. As shown in this figure, the blood
pressure monitor 76 of this embodiment is provided with a second
artery pressing section 80 which presses the ulnar artery 96 as
a second artery.
The second artery pressing section 80 is formed on the 2S second
slide block 78 which can slide along the back of the surface 27
of the mounting mechanism 26. when measuring the blood pressure,
the second artery pressing section 80 presses the ulnar artery 96,
which is the second artery in the wrist, with the controlling action
of the control section 18, thereby interrupting with blood flow
to the peripheral side.
3.2 Operation of Blood Pressure Monitor
Operation of the blood pressure monitor 76 of this embodiment differs
from that of the first embodiment in that the former requires additional
procedure for operating the second artery pressing section 80 which
presses the ulnar artery 96 when measuring the blood pressure.
Specifically, a slide block 78 on which the second artery pressing
section 80 is provided is moved so as to position the second artery
pressing section 80 on the ulnar artery upper 94 in almost the same
timing as in the operation described in connection with the first
embodiment, in which the slide block 28, on which the vibration
sensor 22, artery pressing section 14, and guides 34 are provided,
is positioned on the radial artery 94. Then, the second artery pressing
section 80 presses the ulnar artery 96 with the controlling action
of the control section 18, whereby blood flow to the peripheral
side is interrupted. The blood pressure is measured at the time
of, or after, the interruption of blood flow to the peripheral side
by such pressure application to the ulnar artery 96 by the second
artery pressing section 80.
Except for the above-mentioned operation, the operation of the
blood pressure monitor 76 of this embodiment is the same as the
operation of the blood pressure monitor 10 of the first embodiment.
3.3 Modification of the Third Embodiment
The modification described for the first embodiment can be applied
also to the third embodiment. In addition, the following modification
is possible in this embodiment.
3.3.1 Similar to the differences between the first and second embodiments,
the modified blood pressure monitor 82 which differs from the above-described
embodiment in that this modified embodiment uses a pulse wave sensor
46 instead of the vibration sensor 22, is provided with a conversion
section 50 for converting a pulse waveform into a blood pressure
waveform and a blood-pressure-waveform processing section 54 for
introducing various indicators mentioned in the second embodiment
based on the blood pressure waveform, and has a notification section
62 which can provide not only the information on the maximum and
minimum blood pressures, but also information on the blood pressure
waveform converted by the conversion section 50 and various indicators
introduced by the blood-pressure-waveform processing section 54.
FIG. 16 is a block diagram showing the electric configuration of
the blood pressure monitor 82. The operation of the blood pressure
monitor 82 is the same as the operation of the blood pressure monitor
70 of the second embodiment, except for the addition of the operation
for the above-mentioned second artery pressing section 80. Therefore,
in the blood pressure monitor 82 the conversion section 50 converts
the pulse waveforms obtained from the pulse wave sensor 46 located
on the artery into blood pressure waveforms based on the maximum
and minimum blood pressures which are non-invasively measured by
the blood pressure monitor 82. Therefore, blood pressure waveforms
can be obtained non-invasively by the blood pressure monitor 82.
3.3.2 Although the above embodiment describes an example of the
wrist wherein the first artery is the radial artery 94 and the second
artery is the ulnar artery 96, the first artery of which the vibration
is detected by the vibration sensor may be the ulnar artery 94 and
the second artery of which the blood flow is interrupted by pressing
the second artery pressing section 80 may be the radial artery.
It is also possible to apply this embodiment to fingers, in which
case the first artery may be one of the palmar digital artery and
the second artery the other palmar digital artery, for example.
In this instance, a vibration in one of the palmar digital artery
is detected by the vibration sensor 22, while the blood flow is
interrupted by pressing the other palmar digital artery using the
second artery pressing section 80. In this case, the upper side
of the mounting mechanism 26 should be configured as a circle so
that the vibration sensor 22 and the second artery pressing section
80 may press the finger from opposite sides.
3.4 Effects of the Third Embodiment
As described above, because the blood pressure monitors 76,82 of
this embodiment are provided with the second artery pressing section
80 which locally presses the ulnar artery 96, the effect of pulse
produced by blood flow from the ulnar artery on detection by the
vibration sensor 22 or pulse wave sensor 46 can be prevented. As
a result, accuracy of the blood pressure measurement can be improved.
4. Fourth Embodiment
The pulse wave detection apparatus of the fourth embodiment differs
from the first embodiment in that the former is equipped with a
pulse wave sensor in place of a vibration sensor, has no blood pressure
determination section, and has a waveform processor. Other features
are the same as in the first embodiment, so description thereof
is omitted. Corresponding sections in each figure are indicated
by the same symbols as in the first embodiment.
4.1 Configuration of Pulse Wave Detection Apparatus
In the same manner as in the first embodiment, the pulse wave detection
apparatus 84 of this embodiment is provided with a mounting mechanism
26 as a positioning mechanism, guides 34, an artery pressing section
14, a sensor pressing section 42, a control section 18, and a notification
section 62. The external appearance may be the same as the first
embodiment.
FIG. 17 is a block diagram showing the electric configuration of
the pulse wave detection apparatus 84 of this embodiment. As shown
in this figure, the electric configuration of the pulse wave detection
apparatus 84 of this embodiment differs from that of the blood pressure
monitor 10 of the first embodiment shown in FIG. 4 in that the former
is provided with a pulse wave sensor 46 in place of the vibration
sensor 22, has no blood pressure determination section 30, and has
a waveform processor 86.
The pulse wave sensor 46 detects not only the presence or absence
of a pulse wave due to the flow of blood, but also pulse waveforms
produced by pulse. A pressure sensor, acceleration sensor, distortion
sensor, or microphone, for example, can be used as the pulse wave
sensor 46.
Based on the pulse waveform detected by the pulse wave detection
apparatus 46, the waveform processor 86 calculates the indicators
showing pulse waveform characteristics, such as an after-ejection
pressure ratio .DELTA.BP.sub.P /.DELTA.BP which is the ratio of
the dicrotic wave height .DELTA.BP.sub.D (the pressure difference
between the dicrotic notch blood pressure and the maximum blood
pressure) and the pulse pressure .DELTA.BP (the difference between
the maximum and minimum blood pressures), a dicrotic notch difference
ratio BP.sub.Dd /.DELTA.BP which is the ratio of the dicrotic notch
difference BP.sub.Dd (the difference between the dicrotic notch
pressure and the minimum blood pressure) and the pulse pressure
.DELTA.BP (the difference between the maximum and minimum blood
pressures), a mean blood pressure pulse pressure ratio BP.sub.mean
/.DELTA.BP which is the ratio of the mean blood pressure BP.sub.mean
and the pulse pressure .DELTA.BP (the difference between the maximum
and minimum blood pressures), a dicrotic wave height ratio .DELTA.BP.sub.D
/.DELTA.BP which is the dicrotic wave height .DELTA.BP.sub.D normalized
by the pulse pressure .DELTA.BP, and a dicrotic wave height after-ejection
pressure ratio .DELTA.BP.sub.D /.DELTA.BP.sub.P which is the ratio
of the dicrotic wave height .DELTA.BP.sub.D and the after-ejection
pressure .DELTA.BP.sub.P. (See FIG. 13)
The notification section 62 provides information on pulse waveforms
detected by the pulse wave sensor 46 or various indices made available
by the waveform processor 86, such as an after-ejection pressure
ratio .DELTA.BP.sub.P /.DELTA.BP, a dicrotic notch difference ratio
BP.sub.Dd /.DELTA.BP, a mean blood pressure pulse pressure ratio
BP.sub.mean /.DELTA.BP, a dicrotic wave height ratio .DELTA.BP.sub.D
/.DELTA.BP, and a dicrotic wave height after-ejection pressure ratio
.DELTA.BP.sub.D /.DELTA.BP.sub.P.sub.P, for example.
4.2 operation of Pulse Wave Detection Apparatus
The pulse wave detection apparatus 84 operates as follows, for
example, to detect pulses.
The section to be measured, for example, the wrist is placed in
the prescribed position so that the radial artery 94 of the wrist
may be located close to the pulse sensor 46 of the mounting mechanism
and the palmar side of the wrist may face the surface 27 of the
mounting mechanism 26.
Next, the surface 27 of the mounting mechanism 26 is caused to
descend so that the pulse sensor 46 comes into contact with the
wrist.
Next, the slide block 28 is moved until the pulse sensor 46 and
the artery pressing section 14 come above the radial artery 94.
In this instance, these sections can be easily positioned by causing
the guides 34 to be located on each side of the radial artery 94.
The pressure of the sensor pressing section 42 is adjusted by controlling
the control section 18 so that the radial artery 94 is pressed in
an optimum state for the pulse sensor 46 to detect the pulse from
the radial artery 94.
Next, the pressure applied by the artery pressing section 14 located
on the radial artery 94 is changed to various values by the control
section 18 within the range slightly exceeding the commonly encountered
blood pressure values, for example, in the range from 200 to 30
mmHg, whereupon a pressure enabling the pulse wave sensor 46 to
detect an optimum waveform pattern is selected.
The detected information on pulse waveforms is input into the waveform
processor 86, where the information is processed into various indices
characteristic to pulse waveform patterns, such as pulses, an after-ejection
pressure ratio .DELTA.BP.sub.P /.DELTA.BP, a dicrotic notch difference
ratio BP.sub.Dd /.DELTA.BP, a mean blood pressure pulse pressure
ratio BP.sub.mean /.DELTA.BP, a dicrotic wave height ratio .DELTA.BP.sub.D
/.DELTA.BP, and a dicrotic wave height after-ejection pressure ratio
.DELTA.BP.sub.D /.DELTA.BP.sub.P, for example.
The information on pulse waveforms detected by the pulse wave sensor
46 and information on various indices made available by the waveform
processor 86 are input to the notification section 62. The notification
section 62 presents the information such as a pulse waveform, pulse,
dicrotic notch difference pressure ratio, and mean blood pressure
pulse pressure ratio, as a display such as a numerical value or
a graph, printed characters, or as a voice.
4.3 Modification of the Fourth Embodiment
The modification described for the first embodiment can be applied
also to the fourth embodiment.
4.4 Effects of the Fourth Embodiment
In this pulse wave detection apparatus 84, the pulse wave sensor
46 detects pulse waves at the point of the artery pressing section
14 or on the peripheral side based on variable pressing force values
applied when the artery pressing section 14 locally presses the
artery of the extremities or fingers. Therefore, pulse waves at
various pressures applied by the artery pressing section 14 can
be detected.
In addition, because the pulse wave detection apparatus 84 of this
embodiment is provided with a mounting mechanisms 26 as a positioning
mechanism, the artery pressing section 14 and the pulse wave sensor
46 can be easily positioned on the artery.
Because the pulse wave detection apparatus 84 of this embodiment
is provided with guides which guide the pulse wave sensor on the
artery on each side of the artery, it is possible to locate the
pulse wave sensor 46 on the artery easily and with certainty.
Because the pulse wave detection apparatus 84 is designed so as
to cause the sensor pressing section 42 of the pulse wave sensor
46 to press the artery, it is possible for the pulse wave sensor
to press the artery at an appropriate pressure so that pulse wave
from the artery can be detected with certainty.
5. Fifth Embodiment
5.1 Configuration of Blood Pressure Monitor
FIG. 18 is a schematic view showing blood pressure measurement
using the blood pressure monitor 120 of this embodiment worn on
the wrist. As shown in this figure, the blood pressure monitor 120
of this embodiment is designed so that the blood pressure can be
measured with a cuff-like band 122 wound around the wrist. The band
122 is provided with a pressure applying section 124 in the shape
of a bag and an artery pressing section 126 protruding from the
pressure applying section 124 in the inner side thereof, and is
wound around the wrist so that the artery pressing section 126 may
be located on the point corresponding to the radial artery 94. The
artery pressing section 126 is designed so as to locally press the
radial artery 94 to substantially shut off or restrict blood flow
therein.
The pressure applying section 124 is formed in the shape of a bag
to which a pump 133 and an exhaust valve 134 are connected via a
tube 132. The volume of the pressure addition member 124 is controlled
by adjusting the amount of the fluid, air, for example, filled in
the pressure applying section 124 by using the pump 133 or the exhaust
valve 134, whereby the pressure applied to the radial artery 94
by the artery pressing section 126 can be controlled. The pressure
addition member 124 is of a sufficient size to be located on both
the radial artery 94 and ulnar artery 96 at the same time.
The tube 132 is equipped with a pressure sensor 130 which detects
the pressure change of the fluid. The pressure sensor 130 can detect
a vibration of the radial artery 94, which is conveyed as a fluid
pressure change via the artery pressing section 126 and the pressure
applying section 124. specifically, because the artery pressing
section 126 located above the radial artery 94 is dislocated corresponding
to the vibration of the radial artery 94 and presses the pressure
applying section 124 according to the dislocation, the fluid pressure
in the pressure applying section 124 changes according to the vibration
of the radial artery 94. Accordingly, the pressure sensor 130 which
detects such a pressure change can output signals corresponding
to the vibration of the radial artery 94.
FIG. 19 is a block diagram showing the electric configuration of
the blood pressure monitor 120 of this embodiment. As shown in this
figure, the blood pressure monitor 120 is provided with a control
section 128, a blood pressure determination section 136, and a notification
section 62 in addition to the previously described sections.
The control section 128 controls operation of the pump 133 and
the exhaust valve 132 so that the amount of fluid filled in the
pressure applying section 124 can be adjusted so as to change the
pressure applied by pressure applying section 124. In this manner,
the pressure applied to the radial artery 94 by the artery pressing
section 126 can be varied within the prescribed range. The control
section 128 comprises, for example, a CPU and a memory which stores
a program for operating the CPU.
The blood pressure determination section 136 takes information
on various pressures applied by the artery pressing section 126
from the control section 128, and determines the maximum and minimum
blood pressures based on the signals detected by the pressure sensor
130 at each of these various pressures. The blood pressure determination
section 136 comprises, for example, a CPU and a memory which stores
a program for operating the CPU.
The notification section 62 may comprise a display section which
indicates the blood pressure values determined by the blood pressure
determination section 136 as characters, a graph, or the like, such
as an LCD, CRT, plotter, or printer, for example, or may comprise
a sound creation section which indicates the blood pressure values
by sound, such as a combination of a sound synthesizer and a speaker,
for example.
5.2 Operation of Blood Pressure Monitor
The blood pressure monitor 120 operates as follows, for example,
to measure blood pressure.
A cuff-like band 122 is wound around the wrist so that the artery
pressing section 126 comes to a point corresponding to the radial
artery 94.
The control section 128 controls operation of the pump 133 and
the exhaust valve 134 so that the amount of fluid filled into the
pressure applying section 124 can be adjusted so as to change the
pressure applied by the pressure applying section 124. In this manner,
the pressure applied to the radial artery 94 by the artery pressing
section 126 can be varied within the prescribed range. Specifically,
the pressure applied by the artery pressing section 126 is controlled
by the control section 128 to a range slightly higher than the commonly
encountered blood pressure, for example, in the range of 250 to
20 mmHg.
In each point pressed by the artery pressing section 126, the pressure
sensor 130 which detects a vibration of the radial artery 94 detects
signals corresponding to the vibration of the blood vessel walls
due to the blood which flows through blood vessels constricted by
the artery pressing section 126. The result for each pressure by
the artery pressing section 126 is stored in the blood pressure
determination section 136. Each pressing force value applied by
the artery pressing section 126 is transmitted to the blood pressure
determination section 136 from the control section 128 which controls
the pressing force value.
In the same manner as in the first embodiment, the blood pressure
determination section 136 determines the blood pressure when a sufficient
number of pressure samples is obtained over the above-mentioned
range for the artery pressing section 126.
The information on the maximum and minimum blood pressures thus
determined is transmitted to the notification section 62, and presented
by the notification section 62 as a display such as a numerical
value or a graph, printed characters, or as a voice.
5.3 Modification of the Fifth Embodiment
5.3.1 In the above description, air was given as an example of
the fluid filled into the pressure applying section 124. The fluid
filled into the pressure applying section 124, however, may be other
gases such as oxygen, nitrogen, helium, and argon, or may be a liquid
such as water, mercury, alcohol, or oil. When a fluid other than
air is used, a reservoir for storing such a fluid is necessary.
5.3.2 In the above embodiments, the radial artery 94 was taken
as an example of artery to be pressed by the artery pressing section
126 for detection of pulse using the pressure sensor 130. However,
the artery pressed by the artery pressing section 126 for detection
of a vibration using the pressure sensor 130 is not limited to the
radial artery, but may be any artery in the extremities and fingers
such as the ulnar artery of the wrist, palmar finger artery, brachial
artery, popliteal artery, and the like.
5.3.3 As shown in FIG. 19 in broken lines, the blood pressure monitor
120 may further comprise a conversion section 50 and a blood-pressure-waveform
processing section 54.
The conversion section 50 converts signals detected by the pressure
sensor 130 into a blood pressure waveform using the information
on the maximum and minimum blood pressures determined by the blood
pressure determination section 136. In the detection of signals
used in this conversion by the pressure sensor 130, it is desirable
that a pressure suitable for obtaining a signal waveform close to
the blood pressure waveform from the pressure sensor 130 be applied
to the artery pressing section 126 and pressure applying section
124. Specifically, it is desirable that the control section 128
control the pump 133 and the exhaust valve 134 so that such a pressure
may be applied to the artery pressing section 126 and pressure applying
section 124. In this manner, the blood pressure monitor 120 can
obtain blood pressure waveforms non-invasively. The conversion section
50 comprises, for example, a CPU and a memory which stores a program
for operating the CPU. Using this conversion section 50, the blood
pressure monitor 120 can obtain blood pressure waveforms of the
artery shown in FIG. 13, for example. General matters on the blood
pressure waveform in the artery have been described in connection
with the second embodiment in reference to FIG. 13.
Based on the blood pressure waveform obtained by the conversion
section 50, the blood-pressure-waveform processing section 54 calculates
at least one of the following items: a mean blood pressure BP.sub.mean,
a pulse pressure .DELTA.BP which is the difference between the maximum
and minimum blood pressures, an after-ejection pressure .DELTA.BP.sub.P
which is the pressure difference between the dicrotic notch and
the maximum blood pressure, a dicrotic wave height .DELTA.BP.sub.D
which is the pressure difference between the dicrotic notch and
the dicrotic wave peak, an after-ejection pressure ratio .DELTA.BP.sub.P
/.DELTA.BP which is the after-ejection pressure .DELTA.BP.sub.P
normalized by the pulse pressure .DELTA.BP, and a dicrotic wave
height after-ejection pressure ratio .DELTA.BP.sub.D /.DELTA.BP.sub.P
which is a ratio of the dicrotic wave height .DELTA.BP.sub.D and
the after-ejection pressure .DELTA.BP.sub.P.
Data concerning blood pressure waveforms in the artery obtained
by the conversion section 50 and the above-mentioned various indices
on blood pressure waveforms obtained by the blood-pressure-waveform
processing section 54 are transmitted to the notification section
62, and presented by the notification section 62 as a display such
as a numerical value or a graph, printed characters, or as a voice.
5.4 Effects of the Fifth Embodiment
In the blood pressure monitor 120 of this embodiment, the artery
pressing section 126 installed in the pressure applying section
124 located inside the band 122 locally presses the artery at various
pressures. The blood pressure determination section 136 determines
the maximum and minimum pressures based on the various pressing
force values applied and the signals detected by the pressure sensor
130 at these various pressing force values. Therefore, the artery
is pressed by the artery pressing section 126 at a sufficient pressure
so that the region in which the pressure applying section 124 or
the band 122 come into contact may not become so large. As a result,
a pressure so great as to impart an unpleasant or disagreeable feeling
to the subject will not be applied.
In addition, because the artery pressing section 126 only locally
presses the artery, the pressing operation will not be interfered
with by the sinews or bones which may be present close to the artery
Therefore, the pressing operation can press the artery with certainty,
ensuring measurement of the blood pressure more accurately than
in the conventional method in which the artery is directly pressed
by a cuff or the like applied to the circumference of the extremities
or fingers. Thus, more accurate blood pressure measurement can be
ensured.
In addition, the use of the band 122 similar to cuffs commonly
used for blood pressure measurement and the pressure applying section
124 allows the blood pressure monitor 120 of this embodiment to
be designed as a comparatively small instrument.
6. Sixth Embodiment
The blood pressure monitor of the sixth embodiment is almost the
same as that of the fifth embodiment, except that the former is
a blood pressure monitor for use on the section in which the major
arteries which are the first and second arteries exist comparatively
near the skin, wherein the pressure applying section applies a pressure
directly to the first artery and the pressure sensor detects the
vibration of the first artery conveyed through the pressure applying
section as a pressure change. Another difference is that the pressure
applying section is equipped with a second artery pressing section
which presses the second artery to substantially shut off the blood
flow. Other features are the same as in the fifth embodiment, so
description thereof is omitted. Corresponding sections in each figure
are indicated by the same symbols as in the first embodiment.
6.1 Configuration of Blood Pressure Monitor
FIG. 20 is a schematic view showing blood pressure measurement
using a blood pressure monitor 150 of this embodiment worn on the
wrist. As shown in the figure, the blood pressure monitor 150 of
this embodiment is provided with a second artery pressing section
152 projecting from the pressure applying section 124 and is wound
around the wrist so that the second artery pressing section 152
may be located on the point corresponding to the ulnar artery 96
as the second artery. The second artery pressing section 152 is
designed so as to locally press the ulnar artery 96 to substantially
shut off or restrict blood flow therein. In addition, the pressure
applying section 124 directly contacts and presses the skin above
the radial artery 94 as the first artery.
The pressure sensor 130 can detect a vibration of the radial artery
94 which is conveyed as a fluid pressure change via the pressure
applying section 124. Specifically, because the pressure applying
section 124 located above the radial artery 94 applies pressure
according to the vibration of the radial artery 94, the fluid pressure
in the pressure applying section 124 changes according to the vibration
of the radial artery 94. Accordingly, the pressure sensor 130 which
detects such a pressure change can output signals corresponding
to the vibration of the radial artery 94. When the pressure sensor
130 detects a vibration from the radial artery 94, the second artery
pressing section 152 presses the ulnar artery 96 to substantially
shut off the blood flow therein.
The electric configuration of the blood pressure monitor 120 of
this embodiment is the same as that of the fifth embodiment shown
as a block diagram in FIG. 19. The control section 128 controls
operation of the pump 133 and the exhaust valve 132 so that the
amount of the fluid filled into the pressure applying section 124
can be adjusted so as to vary the pressure applied to the radial
artery 94 within the prescribed range.
6.2 Operation of Blood Pressure Monitor
The blood pressure monitor 120 operates as follows, for example,
to measure blood pressure.
A cuff-like band 122 is wound around the wrist so that the second
artery pressing section 152 comes to a point corresponding to the
ulnar artery 96.
The control section 128 controls operation of the pump 133 and
the exhaust valve 134 so that the amount of fluid filled into the
pressure applying section 124 can be adjusted so as to change the
pressure applied by the pressure applying section 124. In this manner,
the pressure applied to the radial artery 94 by the pressure applying
section 124 can be varied within the prescribed range. Specifically,
the pressure applied by the pressure applying section 124 is controlled
by the control section 128 to a range slightly higher than the commonly
encountered blood pressure, for example, in the range of 250 to
20 mmHg. In this pressure range, the second artery pressing section
152 installed in the pressure applying section 124 presses the ulnar
artery 96 to substantially shut off the blood flow therein.
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