Blood pressure measurement device

A blood pressure and pulse measurement device includes a cuff including a first air bladder, a pressure sensor, a pressing member, a pulse wave sensor, and an operation unit. When measurement of the blood pressure is instructed by the operation unit, the first air bladder of the cuff is inflated to increase inner pressure to a sufficient level such that the blood pressure of the patient can be measured by the pressure sensor and then deflated. When measurement of the blood pressure is not instructed by the operation unit, air of the first air bladder of the cuff is released such that the measurement location of the patient is not substantially pressed by the first air bladder, and the measurement location of the patient is pressed by the pressing member with sufficient pressure such that pulse of the patient can be detected by the pulse wave sensor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a measurement device and a measuring method, more particularly to a measurement device that uses a cuff to measure blood pressure.

2. Description of the Related Art

Based on the nature of a disease, there are cases where it is necessary to capture blood pressure variations of a long period of time, for example, of a circadian pattern and the like. In order to know blood pressure variations, a way of use is known where a measurement device is mounted and blood pressure measurements are performed at predetermined intervals over a long period. Further, there is also a need of desiring to also capture, along with a blood pressure value in the period of time, a variation in pulse in that period of time.

As a sphygmomanometer used to measure blood pressure variations in a long period of time, a wrist sphygmomanometer where a cuff is mounted on a wrist can reduce a burden on a patient over a type where the cuff is mounted on an upper arm. Furthermore, a wrist radial artery can be said to be a suitable area for pulse measurement because the artery is located in a place where a subcutaneous is shallower than the upper arm.

Then, using a wrist sphygmomanometer mounting a function to measure pulse as a device to measure blood pressure and pulse over a long period of time, it can be envisioned that the wrist sphygmomanometer measures pulse in a time period other than at the time of measuring blood pressure.

Here, a method of measuring pulse rate is known where a volume change of an artery in a location where the subcutaneous is relatively shallow is noninvasively detected as a method for measuring pulse. In particular, as measurement methods of simple configuration there are, 1) A method using a cuff that mildly compresses a wrist of the patient and detects variations in cuff pressure with a pressure sensor, and 2) A method that measures the volume change of the artery using a photoelectronic sensor or an impedance sensor mounted and arranged above the artery.

Whether in the case of measuring with the method of 1) or in the case of measuring with the method of 2) above, because a cuff is provided in the sphygmomanometer, use of the cuff is possible. That is, it can be envisioned that the cuff is used for the mild compression of the methods of 1) and 2) above and for attaching the sensors to skin of the method of 2).

Incidentally, the cuff used for blood pressure measurement is configured of an effective size to wrap around a measurement location in a circumferential direction. This size is regulated through, for example, the American Heart Association (AHA) and the like. When attempting to measure continuous pulse on timing other than at the time of measuring blood pressure using this kind of cuff, it is necessary to keep lightly compressing on the wrist of the patient over a long period of time with either the method of 1) or the method of 2) above. Because of that, a possibility increases that a venous flow of an entire circumference of the wrist will be blocked and blood stasis will occur. Also, by compressing the entire circumference of the wrist over a long period of time, the patient may be caused to feel a sense of restraint.

SUMMARY OF THE INVENTION

Accordingly, one or more embodiments of the present invention provide a measurement device that suppresses the occurrence of blood stasis, and also suppresses the burden on the patient and can, along with blood pressure measurement, accurately provide continuous measurement of pulse other than at the time of measuring blood pressure.

One or more embodiments of the present invention relate to a blood pressure and pulse measurement device that comprises a cuff including a first air bladder for wrapping around a measurement location of a patient; a pressure sensor connected to the cuff for measuring an inner pressure of the first air bladder; a pressing member mounted on a portion of an inner face of the first air bladder which contacts the measurement location of the patient when the cuff is wrapped therearound; a pulse wave sensor mounted on the pressing member for detecting pulse of the patient; and an operation unit for instructing the device to measure a blood pressure and pulse. When measurement of the blood pressure is instructed by the operation unit, the first air bladder of the cuff is inflated to increase inner pressure to a sufficient level such that the blood pressure of the patient can be measured by the pressure sensor and then deflated. When measurement of the blood pressure is not instructed by the operation unit, air of the first air bladder of the cuff is released such that the measurement location of the patient is not substantially pressed by the first air bladder, and the measurement location of the patient is pressed by the pressing member with sufficient pressure such that pulse of the patient can be detected by the pulse wave sensor at the position where the measurement location of the patient is contacted by the pulse wave sensor.

According to one or more embodiments of the present invention, the pulse wave sensor is mounted on the pressing member at a position where the pressing member contacts the measurement location.

According to one or more embodiments of the present invention, the pressing member is constituted such that the pulse wave sensor is positioned above the artery of the patient.

According to one or more embodiments of the present invention, the pressing member comprises a second air bladder, and at the time of measuring blood pressure, air of the second air bladder is released such that the measurement location of the patient is substantially pressed only by the first air bladder.

According to one or more embodiments of the present invention, the pulse wave sensor is a photoelectronic sensor

According to one or more embodiments of the present invention, the pulse wave sensor is an impedance sensor.

According to one or more embodiments of the present invention, the cuff and the pressing member is constituted such that they can be mounted on a wrist of the patient.

According to one or more embodiments of the present invention, measurement of blood pressure is instructed by the operation unit at a predetermined interval.

According to one or more embodiments of the present invention, detection of pulse of the patient is suspended when the first air bladder is inflated and/or deflated for measurement of blood pressure.

One or more embodiments of the present invention relate to a cuff of blood pressure and pulse measurement device comprising: a first air bladder for wrapping around a measurement location of the patient; a pressure sensor connected to the first air bladder for measuring an inner pressure of the first air bladder; a pressing member mounted on a portion of an inner face of the air bladder which contacts the measurement location of the patient when the cuff is wrapped therearound; a pulse wave sensor mounted on the pressing member for detecting pulse of the patient; and an operation unit provided in the blood pressure measurement device and connected to the cuff for instructing the device to measure a blood pressure and pulse of the patient. When measurement of the blood pressure is instructed by the operation unit, the first air bladder of the cuff is inflated to increase inner pressure to a sufficient level such that the blood pressure of the patient can be measured by the pressure sensor and then deflated. When measurement of the blood pressure is not instructed by the operation unit, air of the first air bladder of the cuff is released such that the measurement location of the patient is not substantially pressed by the cuff, and the measurement location of the patient is pressed by the pressing member with sufficient pressure such that pulse of the patient can be detected by the pulse wave sensor at the position where the measurement location of the patient is contacted by the pulse wave sensor.

One or more embodiments of the present invention relate to a method for measuring blood pressure and pulse of a patient comprising: wrapping a cuff comprising a first air bladder and a pressure sensor around a measurement location of the patient, wherein the cuff is provided with a pressing member mounted on a portion of an inner face of the first air bladder and a pulse wave sensor mounted on the pressing member; inflating the first air bladder of the cuff to a sufficient inner pressure level such that blood pressure of the patient can be detect by the pressure sensor and then deflated, and releasing air of the first air bladder of the cuff such that measurement location of the patient is not substantially pressed by the air bladder, and the measurement location is pressed by the pressing member with sufficient pressure such that pulse of the patient can be detected by the pulse wave sensor at the position where the pulse wave sensor contacts the measurement location of the patient.

According to one or more embodiments of the present invention, blood pressure and pulse of a patient can be accurately measured in a long period of time while suppressing burden of the patient.

DETAILED DESCRIPTION OF INVENTION

A description will be given hereinafter with reference to drawings of an embodiment of the present invention. In the following description, the same reference numbers will be assigned to the same components and compositional elements. The names and functions of these are also the same.

FIG. 1is a block diagram illustrating a specific example of a device configuration of an electronic sphygmomanometer (herein after a sphygmomanometer)1as a measurement device that relates to an embodiment. The sphygmomanometer1is used to measure blood pressure variation in a long period of time. Because of that, a wrist sphygmomanometer attaching a cuff (air bladder) to a wrist, as mentioned above, is assumed. However, this is not limited to only a wrist, but application is also possible of attachment to locations of other limbs of an upper arm or an ankle and the like.

With reference toFIG. 1, the sphygmomanometer1connects these air bladders, including an air bladder for measuring13and an air bladder for light compression8, to an air system20by an air pipe10through a switching valve24. A pressure sensor23for measuring the inner pressure of air bladders8and13, a pump21for performing inflation/deflation of air bladders8and13and a valve22are included in the air system20.

The pressure sensor23, the pump21and the valve22are each electrically connected to an oscillating circuit28, a drive circuit26, and a drive circuit27. The oscillating circuit28, the drive circuit26and, additionally, the drive circuit27are all electrically connected to the Central Processing Unit (CPU)40that controls the entire sphygmomanometer1. The switching valve24is electrically connected to a drive circuit25and, additionally, the drive circuit25is electrically connected to a CPU40.

Additionally, a display unit4; an operation unit3; a memory6for processing that stores a program executed by the CPU40and becomes an operation region at the time the program is executed; a memory7for data storage for storing required information and the like for measurement results, control, and calculation; a clock80; and a power supply90are connected to the CPU40.

The switching valve24, as one example, corresponds to a 3-port valve comprising the three values of an air bladder8valve, an air bladder13valve and an air system20valve that is driven to open and close the air bladder8valve and the air bladder13valve by the drive circuit25that follows control signals from the CPU40. That is, a state of the air bladder8being connected to the air system20by the air pipe10and a state of the air bladder13being connected to the air system20by the air pipe10are switched following a control signal from the CPU40.

The drive circuit26drives the pump21following the control signal from the CPU40. By so doing, air is infused into air bladder8and also air bladder13.

The drive circuit27drives the valve22by following each control signal from the CPU40. Through this, the valve22is opened and closed.

The pressure sensor23is a capacitance-type pressure sensor in which the capacitance value changes depending on the change in pressure within the air bladders8and13. The pressure sensor23is connected to the oscillating circuit28and the oscillating circuit28converts to a signal with an oscillating frequency according to the capacitance value of the pressure sensor23and is input into the CPU40.

Note that, in this example the air bladder for measuring13and the air bladder for light compression8are both configured to be connected to the air system20across switching valve24, but the air bladder for measuring13and the air bladder for light compression8may also be in a configuration where each is connected to a different air system with separate inner pressure control.

Additionally, with reference toFIG. 1, the sphygmomanometer1includes a photoelectronic sensor30having a light emitting element31and a light receiving element32as a pulse wave sensor for detecting a pulse wave. The light emitting element31irradiates the artery with light, and the light receiving element32receives the light transmitted through the artery. The light emitting element31uses an element that emits light of a high wavelength region near 940 nm, which is a wavelength that easily transmits through body tissue. The light receiving element32also uses an element that receives light of a high wavelength region near 940 nm.

The light emitting element31is electrically connected to a drive circuit33and, additionally, the drive circuit33is electrically connected to the CPU40. The drive circuit33causes the light emitting element31to emit light and quench light following the control signal from the CPU40.

The light receiving element32is electrically connected to an amplification filter circuit34and, additionally, the amplification filter circuit34is electrically connected to the CPU40. The light receiving element32outputs a sensor signal according to the amount of received light to the amplification filter circuit34, and the amplification filter circuit34amplifies the signal a predetermined proportion and outputs the signal to the CPU40.

The air bladder8is used to attach the photoelectronic sensor30to the skin and to lightly compress the artery.

FIG. 2is a schematic indicating a cross section of the mounted portion of a mounted state of the sphygmomanometer1to a wrist that is a measurement location.

With reference toFIG. 2, the photoelectronic sensor30is provided on one side of the air bladder for light compression8as a light source direction on an opposite side to the air bladder8. Then, the sphygmomanometer1is mounted so that the photoelectronic sensor30is above the wrist radial artery. By mounting in this way, the photoelectronic sensor30is pressed in above the wrist radial artery by the air bladder for light compression8.

It is enough if the air bladder8is of a size to cover all of the photoelectronic sensor30and press in above the wrist radial artery, for example, a size where the length of a circumferential direction (wrist circumferential direction) is about 15 mm and a length in a perpendicular direction to that (wrist lengthwise direction) is about 30 mm.

Additionally, with reference toFIG. 2, the air bladder for measuring13contacts a surface of a side opposite to a surface of a side where the photoelectronic sensor30of the air bladder for light compression8is provided and, at the least covers all of the air bladder8. Then, the sphygmomanometer1is mounted by wrapping the air bladder13around the wrist with the air bladder for light compression8as the wrist side, which is the measurement location.

It is enough if the air bladder13is at the least of a size larger than the air bladder for light compression8and to cover all of a cuff for light compression and to wrap around the wrist, for example, a size where the length of a circumferential direction (wrist circumferential direction) is about 150 mm and a length in a perpendicular direction to that (wrist lengthwise direction) is about 45 mm.

A blood pressure measurement operation is performed by the sphygmomanometer1at prescribed timing of a predetermined time interval and the like and when blood pressure measurement is instructed. Also, when blood pressure measurement is not being performed, a pulse measurement operation is performed.

FIG. 3andFIG. 4are diagrams indicating the manner of air bladders8and13at the time of measuring operation.FIG. 3indicates the manner of air bladders8and13at the time of measuring blood pressure, andFIG. 4indicates the manner of air bladders8and13at the time of measuring pulse.

With reference toFIG. 3, at the time of measuring blood pressure, only the air bladder for measuring13pressurizes, the air bladder for light compression8does not pressurize.

With reference toFIG. 4, at the time of measuring pulse, only the air bladder for light compression8pressurizes; the air bladder for measuring13does not pressurize.

Because of this, some burden on a patient occurs at the time of measuring blood pressure because the wrist, which is the measurement location, is compressed by the air bladder for measuring13that has a larger air capacity than the air bladder for light compression8, however, this completes in a short period of time and, at the time of measuring pulse, compression by the air bladder for measuring13is eliminated and compression is only through the air bladder for light compression8that has a smaller air capacity.

FIG. 5is a block diagram illustrating a specific example of a functional configuration of the sphygmomanometer1for performing blood pressure measurement and pulse measurement. Each function illustrated inFIG. 5is formed in the CPU40and executed by the CPU40by retrieving a program stored in the memory6, but at least one portion may be implemented through a hardware configuration of a device configuration and an electric circuit and the like illustrated inFIG. 1.

With reference toFIG. 5, the CPU40includes an instruction input part401for receiving instruction input from the operation unit3, a photoelectronic sensor input part402for receiving input of a sensor signal from the light receiving element32of the photoelectronic sensor30according to a volume of received light, a pressure sensor input part403for receiving input of a sensor signal from the pressure sensor23according to an inner pressure of the air bladder13, a determination part404for determining whether to perform the blood pressure measurement operation or the pulse measurement operation according to the instruction input, a light emission controller405for controlling light emitting and light quenching of the light emitting element31of the photoelectronic sensor30in the case of performing the pulse measurement, an inner pressure controller406for controlling the inner pressure of air bladders8and13in the case of performance of the blood pressure measurement and the pulse measurement, a pulse calculation part407for calculating pulse based on the sensor signal from the photoelectronic sensor30, a blood pressure calculation part408for calculating a blood pressure value based on the sensor signal from the pressure sensor23, a storage part409for storing calculated results in a prescribed area of the memory7and a clock part411including a counter413for measuring an elapsed time from the completion of the pulse measurement operation.

FIG. 6is a flowchart indicating the flow of the measurement operation with the sphygmomanometer1. The operation illustrated in the flow chart inFIG. 6is an operation that starts when a power switch included in an operation unit3is pressed powering on the sphygmomanometer1, and is implemented through the CPU40executing retrieval of the program stored in the memory6and demonstrating each function illustrated inFIG. 5.

With reference toFIG. 6, at step S101, when the sphygmomanometer1is powered on, as an initialization process, the CPU40initializes a memory area for processing, emits the air inside the air bladder for measuring13and the air bladder for light compression8and performs 0 mmHg calibration of the pressure sensor.

After initialization is complete, at step S103, the CPU40switches the switching valve24and upon connecting the air bladder for light compression8to the air system20, closes the valve22and drives the pump21to pressurize the pressure of the air bladder for light compression8to a prescribed pressure. When the inner pressure of the air bladder8reaches an already predetermined prescribed pressure, the driving of the pump is stopped and pressurization stops. Here, the prescribed pressure is already predetermined and refers to a pressure recorded in the memory7(for example, 30 mmHg). Through this, the inner pressure of the air bladder8is maintained at the above already predetermined prescribed pressure.

The CPU40monitors whether or not a measuring switch that instructs the start of blood pressure measurement has been pressed. In the case that the measuring switch has been pressed (YES at step S105), the CPU40determines a case of blood pressure measurement operation and performs the operation for blood pressure measurement.

That is, at step S107, the CPU40completely opens the valve22. By doing so, the air inside the air bladder for light compression8is emitted. After emission, the blood pressure measurement operation is performed at step S109. Here, the blood pressure measurement operation may be a normal blood pressure measurement operation. As one example, a method is utilized where the air bladder for measuring13is pressurized and depressurized and systolic blood pressure and diastolic blood pressure are calculated through the Oscillometric method using those changes in inner pressure.

With respect toFIG. 7about specific operation in this case, at step S201, the CPU40switches switching valve24and closes the valve22upon connecting the air bladder for measuring13to the air system and drives the pump21at a prescribed amount of driving. By doing so, the air bladder for measuring13is gradually pressurized.

When cuff pressure reaches a prescribed pressure (YES at step S205), the CPU_40, at step S207, stops the driving of the pump21and gradually opens the valve22. By doing so, the inner pressure of the air bladder13is gradually depressurized. Here, the prescribed pressure is a pressure sufficiently higher than the systolic blood pressure (for example, systolic blood pressure+30 mmHg) and is either already recorded in memory7or is determined by estimating systolic blood pressure during pressurization.

At step S209, the CPU40, while gradually depressurizing the air bladder13, extracts the pressure variations (pressure pulse wave) in conjunction with artery volume changes superimposed on the air bladder13, applies a prescribed algorithm in the pressure pulse wave signal, and calculates blood pressure. This method can use a conventional Oscillometric method.

Note that, during the time the above blood pressure measurement operation is being performed, according to one or more embodiments of the present invention, the CPU40displays a screen on display unit4, such as that illustrated inFIG. 9. By doing so in this way, the patient and a person measuring can see that the sphygmomanometer1is in the blood pressure measurement operation. Note that, at this time, as illustrated inFIG. 9, the measured pulse may also be displayed together during the blood pressure measurement operation.

After blood pressure is calculated, when blood pressure value is determined (YES at step S211), the CPU40, at step S213, displays a screen on display unit4that indicates measurement results like those ofFIG. 10and, at step S215, saves measurement results in a prescribed area of the memory7(ST209). Note that, at this time, as illustrated inFIG. 10, the measured pulse may also be displayed together during the blood pressure measurement operation.

After that, at step S217, the CPU40completely opens the valve22. By doing so, the air inside the air bladder for measuring13is emitted.

Return toFIG. 6when the above blood pressure measurement operation is complete and the CPU40, at step S111, performs that same operation as at step S103above and once again pressurizes the air bladder for light compression8.

On the other hand, in the case that the measuring switch that instructs the start of blood pressure measurement is not pressed (NO at step105), the CPU40does not perform the blood pressure measurement operation. At this time, the CPU40performs the pulse measurement operation [step S117].

Refer toFIG. 8about the pulse measurement operation at step S117, the CPU40, at step S301, causes the light emitting element31of the photoelectronic sensor30to emit light for a prescribed time period and receives a sensor signal according to the amount of received light from the light receiving element32. After emitting light for a prescribed time period, the CPU40quenches the light emitting element31. Then, at step S303, the CPU40calculates the pulse by applying a prescribed algorithm to the sensor signal.

At step S305, the CPU40saves the calculated pulse in a prescribed area of the memory7. Return toFIG. 6when the above pulse measurement operation is complete and the CPU40, at step S119, starts the measurement of the elapsed time from the completion of the pulse measurement operation. In the case that pulse rate is calculated through the pulse measurement operation at step S117above (NO at step S121), the CPU40, at step S123, resets the counter of the elapsed time from the completion of the pulse measurement operation and repeats the above operation until the power switch is pressed (NO at step S113).

In the case that pulse rate is not calculated through the pulse measurement operation of step S117when the count of the continued measurement of elapsed time is 2 minutes or less (NO at step S125), the measurement of elapsed time continues and the aforementioned operation is repeated until the power switch is pressed (NO at step S113).

Note that, during the time the pulse measurement operation is repeatedly being performed, without the blood pressure measurement operation being performed, according to one or more embodiments of the present invention, the CPU40displays a screen to that effect on display unit4, such as that illustrated inFIG. 11. By doing so in this way, the patient and the person measuring can see that the sphygmomanometer1is in the pulse measurement operation. Note that, at this time, as illustrated inFIG. 11, the results of the repeatedly performed pulse measurements may be displayed together in sequence with the measurement results of the pulse rate at the time of display.

In the case that pulse rate is not calculated through the pulse measurement operation when the count of the continued measurement of elapsed time is 2 minutes or more, that is, in the case where pulse is not calculated for 2 minutes or more (YES at step S125), the CPU40, at step S127, displays a pulse measurement error on display unit4and leaves a flag in the memory7at step S129.

In the case where pulse is not calculated in 2 minutes or more (YES at steps S125and S129) and also when the power switch is pressed (YES at step S113), the CPU40, at step S115, completely opens the valve22and completes the operation. By doing so, the air inside the air bladder for light compression8is emitted and the operation completes.

After a series of operations completes, measurement results like those illustrated inFIG. 12may be displayed. At this time, in the case where a measurement operation of a prescribed period of time is performed, the measurement results of the mechanism, in other words, the various measurement results in the case where blood pressure measurement operations and pulse measurement operations are performed a plurality of times, may be displayed in sequence, as illustrated inFIG. 12. As such, changes during the period of time can be known.

Effect of the Embodiments

With a sphygmomanometer1configured in this way and by operating as aforementioned in timing other than that of a blood pressure measurement operation, a pulse is measured in that period where a narrow extent of above a radial artery of a wrist, which is a measurement location, is lightly compressed by an air bladder8that is smaller than an air bladder13for measuring blood pressure and a sensor for detecting a pulse wave is pressed on the measurement location. Because of this, blood stasis of the wrist can be suppressed and pulse can be measured accurately over a long period of time.

Other Examples

Note that, a photoelectronic sensor is used for pulse wave detection in the above example, but pulse wave detection is not limited to photoelectronic sensors. As other examples, a pulse wave may be detected by detecting a pressure variation in conjunction with an artery volume change superimposed on an inner pressure change of an air bladder for light compression8and an impedance sensor may also be used.

Also, in the example above, an example is illustrated where one photoelectronic sensor having one set of a light emitting element and a light receiving element is used for pulse wave detection, but two or more photoelectronic sensors may be used. Also, as aforementioned, in the case where an impedance sensor is used, two or more impedance sensors may be used.

FIG. 13is a diagram illustrating a specific example of a configuration about a configuration portion related to an inner pressure control of a sphygmomanometer1A using an air bladder for pulse detection.

With reference toFIG. 13, in this case, an air bladder for pulse wave detection8A is provided instead of the air bladder for light compression8and a 5-port valve24A and a switching device35therefor are used as a switching valve24for an air system20. Also, a very slow speed valve29is included in air system20.

The switching device35is connected to a CPU40not illustrated inFIG. 13and follows a control signal therefrom to switch the connection of air bladders8A and13to the air system20with the 5-port valve24A.

Specifically, a connected state at a time of measuring pulse is as illustrated inFIG. 13. That is, at the time of measuring pulse, an air bladder13is opened and the air bladder8A is connected to the air system20. Also, the very slow speed valve29of the air system20is in a state of not being connected. Through this, the air inside air bladder13is emitted and the inner pressure of the air bladder8A is controlled through the air system20.

A connected state at a time of measuring blood pressure is as illustrated inFIG. 14. That is, at the time of measuring blood pressure, the air bladder13is connected to the air system20, and the air bladder8A is connected to the very slow speed valve29. Through this, the inner pressure of the air bladder13is controlled through air system20, and the air inside the air bladder8is gradually emitted from the very slow speed valve29.

FIG. 15andFIG. 16are flowcharts indicating the operation in the sphygmomanometer1A at this time.FIG. 15indicates the pulse measurement operation andFIG. 16indicates the blood pressure measurement operation.

That is, with reference toFIG. 15, the CPU40, upon putting the 5-port valve24A in a connected state of the time of measuring pulse at step S401, as illustrated inFIG. 13, closes a valve22at step S403. Then, at step S405, drives a pump21and pressurizes the air bladder8A until the air bladder8A is at a prescribed pressure. When the above prescribed pressure is reached (YES at step S407), the CPU40, at step S409, stops the driving of the pump21and maintains the prescribed pressure. Then, the CPU40measures pulse at step S411. After that, the CPU40monitors an instruction input to perform blood pressure measurement and, in the case where there is no such input (NO at step S413), the CPU40monitors an instruction input of a stop signal and continues the aforementioned pulse measurement until the instruction input of the stop signal is made (NO at step S415).

Then, when the instruction input of the stop signal is made (YES at step S415), the CPU40opens the valve22at step S417and completes the single series of operations. Through this, the air inside the air bladder8A is emitted and the measurement operation completes.

On the other hand, in the case that the instruction input to perform blood pressure measurement is made (YES at step S413), the CPU40executes the blood pressure measurement operation (step S419).

Specifically, with reference toFIG. 16, the CPU40, upon putting the 5-port valve24A in a connected state of the time of measuring blood pressure in step S501, as illustrated inFIG. 14, drives the pump21and pressurizes the air bladder13until the air bladder13is at a prescribed pressure at step S503. When the above prescribed pressure is reached (YES at step S505), the CPU_40, at step S507, stops the driving of the pump21and gradually opens the valve22at step S509. Through this, the air bladder13is depressurized. The CPU40, at step S511, performs the blood pressure measurement through a decompression process. The blood pressure measurement of step S511is performed until blood pressure is determined (NO at step S513). The CPU40completes the blood pressure measurement operation when blood pressure is determined (YES at step S513) and returns to the pulse measurement operation ofFIG. 15.

FIG. 17is a figure that indicates a change in inner pressure of the air bladder8A (an air bladder for pulse measurement) when performing the blood pressure measurement operation during the pulse measurement operation and then returning to the pulse measurement operation (A) and a change in inner pressure of the air bladder13(the air bladder for blood pressure measurement) (B).

With reference toFIG. 17(A), during the pulse measurement operation, the air bladder8A being generally maintained at a fixed pressure, a pulse wave is detected as a pressure variation in conjunction with an artery volume change superimposed on that pressure change. Because the inner pressure of the air bladder8A is gradually depressurized through the very slow speed valve29at the time of moving from the pulse measurement operation to the blood pressure measurement operation, effects on the blood pressure measurement operation during that period can be suppressed.

With reference toFIG. 17(B), the air bladder13, having no inner pressure compressing the measurement location during the pulse measurement operation, pressurizes and depressurizes as aforementioned during the blood pressure measurement operation. At the same time as blood pressure value is calculated based on a pressure variation in conjunction with a change in artery volume superimposed on a pressure change during that period, pulse is also measured.