WO2001050952A1

WO2001050952A1 - Blood pressure measuring device

Info

Publication number: WO2001050952A1
Application number: PCT/EP2000/011369
Authority: WO
Inventors: Gerhard Frick
Original assignee: Microlife Intellectual Property Gmbh
Priority date: 2000-01-14
Filing date: 2000-11-16
Publication date: 2001-07-19
Also published as: WO2001050952A8; JP2004515257A; PL361421A1; CN100500085C; CN1482883A; EP1333752A1

Abstract

A blood pressure measuring device for measuring the blood pressure on the upper arm of a patient which comprises an inflatable cuff (2) adapted to be placed around the upper arm (A) of the patient is provided with an electric or electronic pressure sensor (5). The device is formed as a hand held device which comprises a bulb (8) attached to a housing (9) including the control and display unit (7) for inflating the cuff (2). Blood pressure is automatically determined in an oscillometric method.

Description

Blood pressure measuring device

The invention relates to a device for measuring the blood pressure of a patient according to the preamble of the independent patent claims .

It is known to measure the blood pressure of a patient by applying an inflatable cuff around the upper arm of the patient. The pressure values within the cuff are displayed with a mechanic or with a mercury manometer. A stethoscope is placed between the upper arm of the patient and the inflated cuff. The pressure values displayed on the manometer, when Korotkoff sounds appear or disappear during deflation of the cuff, give the systolic and diastolic blood pressure values. This blood pressuring method is appreciated by doctors because of the sufficiently high accuracy achieved through simple devices and because of the possibility of additional diagnostics when using a stethoscope.

It is further known to measure the blood pressure completely electronically, e.g. based on an oscillometric method. Depending a pressure signal measured within the cuff, the values of the systolic and the diastolic blood pressure are calculated with an algorithm and displayed on a digital display.

Such automatic blood pressure monitors usually have an electric pump for inflating the cuff. Such a pump has several drawbacks: The operation of the electric pump leads to a high consumption of energy. A frequent change of batteries is therefore necessary. In addition, the pumping speed is limited to the power of the electric pump. A faster inflation which may be desired by some patients is not achievable. In addition, some patients are scared of automatic pumping. There are also known so-called semi-automatic blood pressure monitors which are provided with a bulb for manually inflating the cuff. The bulb is connected to the cuff with a tube. These known devices also have several drawbacks: The use of three separate devices (cuff/bulb/measuring and display unit) is not comfortable .

Especially for elderly or disabled persons, proper use of such devices may be difficult. The tubing necessary to connect the display unit to the cuff and the bulb to the cuff makes these blood pressure monitors more susceptible to mechanical damages. Further these type of devices always need a table or a surface for the display unit to be placed on during measurement, which is a major drawback especially for hospital use, where mobile application or application directly at the patients bed is the usual case .

It is an object of the present invention to overcome the drawbacks of the prior art, especially to provide an automatic blood pressure measuring device which allows easy and accurate measurement of the blood pressure values, which allows operation with a low consumption of energy and which is easy to be used. A further object of the present invention is to improve the comfort for the patient and to improve the reliability of the blood pressure monitor.

These and other objects are solved according to the present invention with a blood pressure measuring device according to characterising part of the independent patent claims.

The blood pressuring device according to the present invention is used for oscillometrically measuring the blood pressure of a patient, e.g. upon the upper arm. The device comprises an inflatable cuff which is adapted to be placed around the upper arm. The blood pressure measuring device further comprises a control and display unit connected to or connectable to the cuff via a tube.

The control and display unit is provided with at least one electric or electronic pressure sensor for measuring the pressure within the cuff. The control and display unit further comprises a digital display and a calculating unit. The calculating unit is programmed in such a way that the systolic and diastolic blood pressure values are calculated on the basis of the pressure oscillations in the cuff measured by the pressure sensor. Calculation is made in a known manner, e.g. with the oscillometric method.

According to the invention , the control and display unit is provided with a bulb for manually inflating the cuff.

The bulb is directly attached to a housing including the control and display unit. The invention proposes an integral, manual, hand held blood pressure monitor which automatically determines the blood pressure values in an oscillometric method and which comprises a manual inflation bulb which is integrated in a housing carrying the control and display unit . The housing may therefore be simply held with one hand while the bulb may be pressed with the fingers of the same hand.

Preferably, the housing includes the pressure sensor, the calculating unit, the pressure control valves, the display and the inflation bulb. Pressure control valves include a valve for pressure reduction during the measurement and a release valve for pressure release after the measurement . Both valves can be mechanical or automatic/electric valves. The blood pressure monitor substantially consist of two parts, the housing with the control and display unit and the cuff, which are connected to each other with only one tube .

In the case of an automatic deflation valve, the deflation valve can also act as the pressure release valve. During the measurement, the valve slowly decreases the pressure in the cuff and works as a deflation valve. After the measurement, the valve rapidly decreases the pressure and acts as a pressure release valve .

The blood pressure measuring device according to the invention has several advantages. As the device consists only of two parts, it is easy to use because there is no need for an electrically operated pump. Consumption of energy is greatly reduced and batteries last over a long period of time. In addition, the user may select the speed of inflating the cuff at its discretion.

In a preferred embodiment the calculating unit is provided with an on/off switch. The switch may be activated upon first compression of the bulb. As soon as the user starts to inflate the cuff, the switch is activated and the calculating unit is turned on. The device may further comprise a timer which turns off the calculating unit after a certain period of time. It is therefore possible to make a blood pressure monitor without an external switch. This design allows an easy operation, because the user does not need to turn the device on before making a measurement . In addition, the device can be manufactured in an economical way because additional manual switches can be dispensed with. An automatic power off switch which additionally helps to save energy of the batteries. In a further preferred embodiment, the calculating unit is programmed such as to indicate when the cuff pressure has reached the required setup pressure. This indicates the user when he may stop to inflate the cuff. It is also possible to indicate, that the setup pressure of the cuff pressure has not yet been reached and further inflation is required. It is further conceivable to automatically start the blood pressure measurement as soon as the setup pressure of the pressure in the cuff is reached and starts to decline. The measurement cannot start as long as the pump is actuated, i.e. the pressure increases.

The control and display unit may be provided with an automatic pressure release valve for automatically releasing the cuff pressure after the measurement, which means after the diastolic blood pressure value is determined. This feature on the one hand provides more comfort to the user, but on the other hand requires at least one OFF button for manually triggering the release valve in case the patient feels uncomfortable while the cuff is still under pressure.

Further the device may be equipped with an active controlled deflation valve which has the advantage that it may be controlled with the calculation unit, whereby under each specific condition (e.g. at high or low pulse rates) an optimum deflation speed may be achieved.

In an alternative embodiment, the deflation valve is formed as passive, self regulating valve. Such valves are known as such. The valve is operating in a way such that the decrease of the pressure within the cuff is continuously between around two and five mmHg per second, independent from the pressure within the cuff. Such a valve may remain open during the inflation of the cuff, as the inflation speed is much higher than the deflation rate. Such valve may be combined with a manual quick release function by pressing a button. This allows an especially user friendly design of the blood pressure measuring device with very low cost of material, at the same time. In order to make a measurement, the user only has to inflate the cuff with the manual inflation bulb. As soon the desired pressure in the cuff is reached, the user may stop inflating the cuff and the measurement of the blood pressure is made fully automatic. After the diastolic pressure is determined the user simply presses the valve button for manually releasing the remaining pressure within the cuff.

The inflation bulb, and the manual deflation valve if present are arranged in such way that they are actuatable with one hand. Such an arrangement leads to an ergonomic design which allows the user to make the entire measurement with one hand while the other hand remains free .

The calculating unit may further be programmed such as to calculate the pulse rate of the patient and to control the deflation rate of the deflation valve

The invention will be more clearly understood on behalf of the accompanying drawing, which show:

Figure 1 a schematic representation of a blood pressure measuring device according to the invention and

Figure 2 a representation of the bulb arranged within the blood pressure measuring device and Figure 3 an exploded view of the blood pressure measuring device, showing the individual components of the device.

The blood pressure measuring device 1 according to the present invention is schematically shown in Figure 1. The device 1 comprises a cuff 2 and a control and display unit 3.

The cuff 2 is adapted to be placed around the upper arm of a patient

The control and display unit 3 is connected to the inflatable cuff 2 via a tube 4. The control and display unit 3 comprises a pressure sensor (not shown) for measuring the pressure P within the cuff. The control and display unit 3 is arranged in a housing 9 made up of a plastic material.

The housing 9 is further provided with a bulb 8 for manually inflating the cuff 2 and optionally with a combined valve 11 for pressure decrease during measurement and for manually deflating the cuff 2 after the measurement. The bulb 8 is attached to the housing such that the housing can be directly held and the bulb can be actuated with the same hand.

Based on an electric signal provided by the electric or electronic pressure sensor, the value of the blood pressure is calculated in an oscillometric method.

Calculation is made with a calculating unit 7, which is integrated in the control and display unit 3. The calculating unit 7 is a microprocessor, e.g. of the Mitsubishi 3822 series. The signal of the pressure sensor is coupled into the calculating unit 7. Measurement of the blood pressure is made as follows: In an embodiment of the invention, the blood pressure monitor is provided with an Auto-on function. When the user for the first time presses the inflation bulb 8, the calculating unit 7 is turned on.

The microprocessor may in its sleeping-mode continuously check the pressure at the sensor and switch on the display (and close the automatic release valve, when applicable) after reaching a predetermined pressure, e.g. above 20 mmHg. Another, more energy saving way is to include an additional pressure sensitive micro- switch in the system.

Without such auto-switch-on feature, the unit may be manually switched on before the user starts to pump in a similar way as it is made in known manual blood pressure monitors.

The cuff is thereafter inflated by further pressing the bulb 8 to a pressure value P, e.g about 40 mmHg higher than the expected systolic blood pressure of the patient. If the pumped cuff-pressure P is too low, the algorithm will detect this and indicate on the display to further pump the cuff to a higher value. After inflation of the cuff, the pressure in the cuff 2 is gradually released and the pressure values in the cuff 2 are measured.

In a first embodiment, the pressure is automatically released with a passive self-regulating valve 11. During the deflation process, the values of the pressure P in the cuff 2 are continuously measured with the pressure sensor and the calculating unit 7. After the deflation of the cuff, the value of the systolic and diastolic blood pressure are determined with the calculating unit 7 in an oscillometric method. The oscillometric method for determining the blood pressure is known per se . Based on the measurement of the pressure during the deflation process, it is also possible to determine the pulse rate of the patient. For determining the pulse rate, the time difference between pressure maxima and/or minima within the cuff 2 are determined with the calculating unit 7. After the deflation process, the blood pressure values and, optionally, the pulse rate are displayed in the digital display 6.

In a further embodiment, instead of a passive deflation valve, there is arranged an automatic deflation valve e.g. an electromagnetic valve. The deflation rate in this case is controlled with the calculating unit.

After the measurement cycle which is finished by displaying the blood pressure values and, optionally, the pulse rate and when the remaining cuff pressure is released, the blood pressure monitor is automatically turned off after a certain period of time without operation, e.g. after five minutes unless there is a switch-off button and it is pressed after measurement.

Figure 2 shows an exploded view of an embodiment of the control and display unit 3 according to the invention.

The housing 9 of the blood pressure measuring device 1 consists of a lower cover 32 and an upper cover 31. The lower and upper covers 32, 31 are made of plastic material, e.g. formed in injection molding. The upper cover 31 is provided with a shell 34. The bulb 8 is partially covered by the shell 34 which acts as a counter bearing for the bulb 8. The bulb 8 is attached with a bulb holder 33 to the upper cover 31. The control and display unit 3 formed basically the bulb 8, the upper cover 31 and the lower cover 32 is connected to a cuff via a tube 4. The bulb 8 is provided with a manual release valve 11 for rapidly releasing the cuff pressure. The bulb 8 is provided with an automatic or passive deflation valve 11 for deflation of the cuff during the measurement and with a check valve 10 for air inlet into the bulb. A conventional pressure sensor 5, a printed circuit board 30 with a microprocessor and a digital display 6 are arranged in the housing 9 formed of the upper and lower cover 31, 32. Those parts are known to those skilled in the art. Additional parts for fixation of the elements, electrical connection, switching on or off, known to those skilled in the art are also shown in figure 2.

The shell 34 is provided with a hole 35 as an air inlet through which the check valve 11 is inserted. This helps, to fix the bulb 8 additionally within the shell 34. For inflation of the cuff, the blood pressure measuring device may be held with one hand at the shell 34. The bulb 8 may be actuated with the fingers of the same hand.

The blood pressure values measured are displayed with the digital display 6 which may be seen by the user through an opening closed with a lens 36 on the upper cover 31 of the housing 9. For quick release of the pressure, the user may actuate the release valve 11 with a finger of the same hand.

Figure 3 shows a schematic representation of the blood pressuring device 1. Same reference numerals designate same parts as in Figure 1.

The pressure P within the cuff 2 is measured with a electronic or electric pressure sensor 5. The pressure P in the cuff 2 is increased with a bulb 8 and may be decreased with a valve 11.

The electrical signal provided by the pressure sensor 5 is led to oscillometric circuit 15. The pressure P is determined in the oscillometric circuit 15 based on the electric signal. The output of the oscillometric circuit 15 is led into the microprocessor 7. The values of the systolic and diastolic blood pressure are calculated with the microprocessor 7 and displayed on the display 6. The power for the device is supplied by a battery 13 being connected to the microprocessor 7 and via a power driver 16 to the voltage regulator 17 and to the oscillometric circuit 15. The device is further provided with a low battery potentiometer 18 connected to the power driver 17 and the microprocessor 7.

An oscillator 19 is further provided for operating the microprocessor 7. The microprocessor 7 determines the blood values on the basis of the pressure P with the oscillometric method.

The components used in the device 1 are known to those skilled in the art .

Claims

1. An automatic, hand held blood pressure measuring device (1) for measuring the blood pressure of a patient, comprising:

an inflatable cuff (2) adapted to be placed around the upper arm (A) or the wrist of the patient,

a housing (9) having a control and display unit (3) which is connected to or connectable to the the cuff (2) via a tube (4) , said control and display unit including at least one electric or electronic pressure sensor (5) for measuring the pressure (P) within the cuff, a calculating unit (7) for os- cillometrically calculating the value of the blood pressure on the basis of the pressure values in the cuff , and a display (6) ,

and a bulb (8) for manually inflating said cuff (2),

wherein said bulb (8) is attached to said housing (9) , thereby allowing holding the said housing (9) and inflating the bulb (8) with one hand.

2. A blood pressure monitor according to claim 1, wherein said calculating unit (7) is provided with an on/off switch, the switch being optionally activatable through a first compression of the bulb (8) .

3. A blood pressure monitor according to one of the claims 1 or 2, characterized in that the control and display unit (3) comprises a passive, self-regulating deflation valve (11) .

4. A blood pressure monitor according to one of the claims 1 to 3, characterized in that the calculating unit (7) is programmed such as to indicate when the pressure (P) in the cuff (2) has reached a setup value or such as to indicate when the pressure (P) in the cuff has not yet reached a setup value .

5. A blood pressure measuring device according to one of the claims 1 or 2 , wherein the device comprises a manual or an automatic pressure release valve (11) .

6. A blood pressure measuring device according to claim 5, wherein the inflation bulb (8) , and the manual pressure release valve are arranged in such a way that they are ac- tuatable with one hand.

7. A blood pressure measuring device according to one of the claims 1 to 6, wherein the calculating unit (7) is further designed and programmed to calculate the pulse rate of the patient and optionally to control the deflation rate of the valve .