US-12622648-B2 - Control device for controlling a measurement system for measuring blood pressure

Abstract

The invention relates to a control device for controlling a blood pressure measurement system. An applicator applies increasing pressure to a subject's part in a measurement time period, while the pressure (TP) on the skin of the subject's part, which comprises a plurality of pressure pulses ( 9 ), is measured. For each pressure pulse of at least some of the plurality of pressure pulses, several features, which characterize the respective pressure pulse, are determined, wherein an end measurement time point ( 32 ), at or after which the measurement time period is to be stopped, is determined based on these features, and wherein, when or after the end measurement time point has been reached, i.e. when the measurement time period is to be stopped, the applied pressure is decreased to start the following post-blood-pressure-measurement time period. This allows for a reduced blood pressure measurement time and maximum tissue pressure exerted on the skin.

Inventors

• Ulrich Joachim PFEIFFER
• Benjamin Stolze
• Stephan Guido Maria REGH
• Mahad Amer AKHTER

Assignees

• KONINKLIJKE PHILIPS N.V.

Dates

Publication Date

20260512

Application Date

20200109

Priority Date

20190114

Claims (20)

1. 1 . A control device for controlling a measurement system for measuring blood pressure of a subject, wherein the measurement system comprises a) a shell configured to encase a part of the subject, through which blood flows, b) a pressure applicator configured to apply, from outside the shell, pressure to the shell and thereby to the encased part of the subject, and c) a pressure sensor configured to measure the pressure (TP) on the skin of the encased part of the subject, wherein the control device is configured to control the measurement system such that: the pressure applicator increases the applied pressure in a measurement time period and decreases the applied pressure in a following post-blood-pressure-measurement time period, the pressure sensor measures the pressure on the skin at least during the measurement time period, wherein the measured pressure (TP) comprises a plurality of pressure pulses, wherein the control device is configured to determine, for each pressure pulse of at least some of the plurality of pressure pulses, several features comprising at least: (i) a duration of a respective features determination pulse (t(pulse)); (ii) an area of the respective features determination pulse (TPA/TPA.norm); (iii) a difference (TPP) between a features determination pulse's maximum systolic pressure (TPsys) and a features determination pulse's pressure at the end-diastolic point (TPdia); and (iv) a width at half maximum (W50) of the respective features determination pulse, which characterize the respective pressure pulse, to determine an end measurement time point, at or after which the measurement time period is to be stopped, based on the features TPP, t(Pulse), TPA/TPA.norm, and W50 determined for the at least some of the plurality of pressure pulses, and to control the pressure applicator such that, when or after the end measurement time point has been reached, said pressure applicator decreases the applied pressure to start the following post-blood-pressure-measurement time period; wherein the control device is configured to, in order to determine for a respective pressure pulse several features, provide a features determination pulse based on the respective pressure pulse, and determine at least two of the following features: (i) the difference (TPP) between the features determination pulse's maximum systolic pressure (TPsys) and the features determination pulse's pressure at the end-diastolic point (TPdia); (ii) the duration (t(pulse)) of the respective features determination pulse; (iii) the area (TPA/TPA.norm) of the respective features determination pulse; and (iv) the width at half maximum (W50) of the respective features determination pulse; and wherein the control device is configured to determine an end determination combination value (TPWP_E) for a respective pressure pulse based on at least one of the following calculations: (1) multiplying a) the area (TPA/TPA.norm) to the power of a predetermined first exponent (exp1) with b) the difference (TPP) to the power of a predetermined second exponent (exp2); (2) dividing a) the area (TPA/TPA.norm) to the power of a predetermined third exponent (exp3) by b) the duration (t(pulse)) to the power of a predetermined fourth exponent (exp4) to produce a first resulting quotient; and multiplying the first resulting quotient with c) the difference (TPP) to the power of a predetermined fifth exponent (exp5).
2. 2 . The control device as defined by claim 1 , wherein the control device is configured to determine: for a respective pressure pulse, an end determination combination value (TPWP_E) by combining at least two of the features (TPP, t(Pulse), TPA/TPA.norm, W50), which have been determined for the respective pressure pulse, such that for several pressure pulses, which are present at different times, several end determination combination values (TPWP_E) are determined, wherein the several end determination combination values (TPWP_E) determined for the several pressure pulses and hence for the several times form an end determination curve (TPWP_E-curve), and the end measurement time point based on the formed end determination curve (TPWP_E-curve).
3. 3 . The control device as defined by claim 1 , wherein the control device is configured to determine an end determination combination value (TPWP_E) for a respective pressure pulse based on a further multiplication with the width at half maximum to the power of a further predetermined exponent.
4. 4 . The control device as defined by claim 1 , wherein the control device is configured to determine: for a respective pressure pulse a blood pressure determination combination value (TPWP_M) by combining at least two of the determined features (TPP, t(Pulse), TPA/TPA.norm, W50) such that for several pressure pulses, which are present at different times, several blood pressure determination combination values (TPWP_M) are determined, wherein the several blood pressure determination combination values (TPWP_M) determined for the several pressure pulses and hence for several times form a blood pressure determination curve (TPWP_M-curve), the blood pressure based on the blood pressure determination curve (TPWP_M-curve).
5. 5 . The control device as defined by claim 4 , wherein the control device is configured to determine a maximum of the blood pressure determination curve (TPWP_M-curve) and to determine the blood pressure based on the determined maximum and the measured pressure (TP).
6. 6 . The control device as defined by claim 4 , wherein the control device is configured to determine a blood pressure determination combination value (TPWP_M) for a respective pressure pulse based on at least one of the following calculations: multiplying a) the determined area (TPA/TPA.norm) to the power of a predetermined tenth exponent (exp10) with b) the determined difference (TPP) to the power of a predetermined eleventh exponent (exp 11), dividing a) the determined area (TPA/TPA.norm) to the power of a predetermined twelfth exponent (exp12) by b) the determined duration (t(pulse)) to the power of a predetermined thirteenth exponent (exp13) so as to produce a second resulting quotient and multiplying the second resulting quotient with c) the determined difference (TPP) to the power of a predetermined fourteenth exponent (exp14).
7. 7 . The control device as defined by claim 6 , wherein the control device is configured to determine a blood pressure determination combination value (TPWP_M) for a respective pressure pulse based on a further multiplication with the width at half maximum (W50) to the power of a further predetermined exponent.
8. 8 . The control device as defined by claim 5 , wherein the control device is configured to determine the end determination curve (TPWP_E-curve) such that it fulfills one of the following conditions: a maximum of the end determination curve (TPWP_E-curve) occurs temporally before a maximum of the blood pressure determination curve (TPWP_M-curve), a maximum of the end determination curve (TPWP_E-curve) occurs temporally at or after a maximum of the blood pressure determination curve (TPWP_M-curve) and the decrease of the end determination curve (TPWP_E-curve) after its maximum is steeper than the decrease of the blood pressure determination curve (TPWP_M-curve) after its maximum, and the end determination curve (TPWPE-curve) is identical to the blood pressure determination curve (TPWP_M-curve).
9. 9 . The control device as defined by claim 2 , wherein the control device is configured to determine: for a respective pressure pulse a blood pressure determination combination value (TPWP_M) by combining at least two of the determined features (TPP, t(Pulse), TPA/TPA.norm, W50) such that for several pressure pulses, which are present at different times, several blood pressure determination combination values (TPWP_M) are determined, wherein the several blood pressure determination combination values (TP WP M) determined for the several pressure pulses and hence for several times form a blood pressure determination curve (TPWP_M-curve), the blood pressure based on the blood pressure determination curve (TPWP_M-curve), and the end measurement time point further based on the blood pressure determination curve (TPWP_M-curve).
10. 10 . The control device as defined by claim 9 , wherein the control device is configured to determine the end measurement time point by determining when a) the end determination curve (TPWP_E-curve) has fallen, after having passed its maximum, to a value being equal to or smaller than a predefined percentage of the maximum and b) the blood pressure determination curve (TPWP_M-curve) has reached or passed its maximum.
11. 11 . The control device as defined by claim 10 , wherein the predefined percentage of the maximum is within a range from 40 percent to 95 percent.
12. 12 . The control device as defined by claim 1 , wherein the control device is configured to control the pressure applicator such that it increases the applied pressure with a first rate in a pre-measurement time period which is followed by the measurement time period in which the applied pressure is increased with a second rate, wherein the first rate is larger than the second rate.
13. 13 . The control device as defined by claim 12 , wherein the control device is configured to control the pressure applicator such that at the end of the pre-measurement time period the measured pressure (TP) is within the range of 15 to 30 mmHg.
14. 14 . The control device as defined by claim 12 , wherein the control device is configured to: store or receive a previous diastolic arterial pressure (DAPprev) obtained by a previous blood pressure measurement, determine a first end measured pressure (TPlow), which should be present at the end of the pre-measurement time period, depending on the previous diastolic arterial pressure (DAPprev) such that the first end measured pressure (TPlow) is smaller than the previous diastolic arterial pressure (DAPprev), control the pressure applicator such that the measured pressure (TP) at the end of the pre-measurement time period is equal to or smaller than the determined first end measured pressure (TPlow).
15. 15 . The control device as defined in claim 14 , wherein the control device is configured to determine the first end measured pressure (TPlow) such that it is 90 percent or less of the previous diastolic arterial pressure (DAPprev).
16. 16 . The control device as defined by claim 14 , wherein the control device is configured to further store or receive the time at which the previous diastolic arterial pressure (DAPprev) had been measured and to determine the first end measured pressure (TPlow) depending on i) the previous diastolic arterial pressure (DAPprev) and ii) a temporal distance to the blood pressure measurement, at which the previous diastolic arterial pressure (DAPprev) had been measured, as indicated by the stored time.
17. 17 . The control device as defined by claim 12 , wherein the control device is configured to: store or receive a previous pressure measured by the pressure sensor in a time period in between an end of a previous measurement time period of a previous blood pressure measurement and a start of the pre-measurement time, control the pressure applicator such that the measured pressure (TP) at the start of the pre-measurement time period is equal to or smaller than a predefined pressure value based on the stored or received previous measure.
18. 18 . A measurement system for measuring blood pressure of a subject, wherein the measurement system comprises: a shell configured to encase a part of the subject, through which blood flows, a pressure applicator configured to apply, from outside the shell, pressure to the shell and thereby to the encased part of the subject, a pressure sensor configured to measure the pressure (TP) on the skin of the encased part of the subject, and a control device as defined in claim 1 .
19. 19 . A control method for controlling a measurement system as defined by claim 18 , wherein the control method includes: increasing the applied pressure in a measurement time period and decreasing the applied pressure in a following post-blood-pressure-measurement time period by using the pressure applicator, measuring the pressure (TP) on the skin at least during the measurement time period by using the pressure sensor, wherein the measured pressure (TP) comprises a plurality of pressure pulses, wherein, for each pressure pulse of at least some of the plurality of pressure pulses, several features (TPP, t(Pulse), TPA, TPA.norm, W50), which characterize the respective pressure pulse are determined and wherein an end measurement time point, at or after which the measurement time period is to be stopped, is determined based on the features (TPP, t(Pulse), TPA/TPA.norm, W50) determined for the at least some of the plurality of pressure pulses, and wherein the pressure applicator is controlled such that, when or after the end measurement time point has been reached, it decreases the applied pressure to start the following post-blood-pressure-measurement time period.
20. 20 . A computer program for controlling a measurement system, the computer program comprising non-transitory program code means for causing the measurement system to carry out the steps of claim 19 , when the computer program is run on the control device of the measurement system.

Description

This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2020/050347, filed on 9 Jan. 2020, which claims the benefit of European Application Serial No. 19151589.9, filed 14 Jan. 2019 and European Application Serial No. 19208237.8, field 11 Nov. 2019. These applications are hereby incorporated by reference herein. FIELD OF THE INVENTION The invention relates to a control device for controlling a measurement system for measuring blood pressure of a subject. The invention relates further to the measurement system for measuring blood pressure of the subject, and a control method and a computer program for controlling the measurement system. BACKGROUND OF THE INVENTION EP 3 430 992 A1 discloses a blood pressure measuring system configured to surround a subject's body part, wherein the blood pressure measuring system comprises pressurization means for applying pressure to the body part and a kinking-proof shell. The kinking-proof shell is arranged to be located between the pressurization means and the body part, when the blood pressure measuring system surrounds the body part. The blood pressure measuring system allows measuring the blood pressure very accurately by continuously raising clamping pressure and stopping the rise above systolic blood pressure, but it is desired to reduce the time needed for carrying out the blood pressure measurement and the maximum clamping pressure exerted on the body part during the measurement. SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for controlling a measurement system for measuring blood pressure of a subject, which allows for a reduced measurement time and for a reduced maximum clamping pressure exerted on the subject. It is a further object of the present invention to provide a measurement system for measuring blood pressure of a subject comprising the control device, and a control method and a computer program for controlling the measurement system. In a first aspect of the invention a control device for controlling a measurement system for measuring blood pressure of a subject is presented, wherein the measurement system comprises a) a shell configured to encase a part of the subject, through which blood flows, b) a pressure applicator configured to apply, from outside the shell, pressure to the shell and thereby to the encased part of the subject, and c) a pressure sensor configured to measure the pressure on the skin of the encased part of the subject, wherein the control device is configured to control the measurement system such that the pressure applicator increases the applied pressure in a measurement time period and decreases the applied pressure in a following post-blood-pressure-measurement time period,the pressure sensor measures the pressure on the skin at least during the measurement time period,wherein the measured pressure comprises a plurality of pressure pulses, wherein the control device is configured to determine, for each pressure pulse of at least some of the plurality of pressure pulses, several features, which characterize the respective pressure pulse, to determine an end measurement time point, at which the measurement time period is to be stopped, based on the features determined for the at least some of the plurality of pressure pulses, and to control the pressure applicator such that, when or after the end measurement time point has been reached, it decreases the applied pressure to start the following post-blood-pressure-measurement time period. It has been found that features determined for the pressure pulses can be used for determining an end measurement time point such that the measurement time period is relatively short and nevertheless enough pressure data have been measured, which allow for an accurate determination of the blood pressure. This allows for a reduced blood pressure measurement time and tissue pressure, i.e. the clamping pressure exerted on the skin of the body part, during measurement staying and ending substantially below systolic arterial pressure. The features can directly characterize the respective pressure pulse or indirectly characterize the respective pressure pulse. In the latter case the respective pressure pulse is processed for determining a features determination pulse and the features are determined based on the determined features determination pulse. This will be explained in more detail further below. The control device can be configured to determine, for each pressure pulse of, for instance, at least 5 or at least 10 of the plurality of pressure pulses, several features, which characterize the respective pressure pulse. The control device can also be configured to determine, for each pressure pulse of the plurality of pressure pulses, several features which characterize the respective pressure pulse. In an embodiment the pressure sensor, which is configured to measure the pressure on the skin of