Method, apparatus and computer program for determining a blood pressure value

Patent metadata

Field	Value
Publication number	US-11864874-B2
Application number	US-201515543299-A
Country	US
Kind code	B2
Filing date	Jun 18, 2015
Priority date	Jun 18, 2015
Publication date	Jan 9, 2024
Grant date	Jan 9, 2024

Abstract

Method for determining a blood pressure value including the steps of: providing a pulsatility signal, determining a time-related feature and a normalized amplitude-related feature on the basis of the pulsatility signal; and calculating a blood pressure value on the basis of a blood pressure function depending on the time-related feature, the normalized amplitude-related feature and function parameters.

First claim

What is claimed is:

1. Method for determining a blood pressure value comprising the steps of:
providing a pulsatility signal of a user, the pulsatility signal comprising a plurality of pulses;
selecting only one pulse of the plurality of pulses of the pulsatility signal;
for the selected only one pulse, determining a first feature and a second feature on the basis of the pulsatility signal; and
calculating a blood pressure value on the basis of a blood pressure function depending on the first feature, the second feature, and function parameters, the first feature being a time-related feature comprising a time duration within the selected only one pulse, and the second feature being a normalized amplitude-related feature,
wherein the calculating does not use a non-normalized amplitude-related feature,
wherein the normalized amplitude-related feature is an amplitude-related feature normalized by another amplitude-related feature,
wherein the blood pressure function further linearly depends on a user feature,
wherein the function parameters comprise a time-related coefficient, an amplitude-related coefficient, and a user coefficient,
wherein the time-related feature is multiplied with the time-related coefficient, the normalized amplitude-related feature is multiplied with the amplitude-related coefficient before summing the time-related feature with the normalized amplitude-related feature,
wherein the user feature is multiplied with the user coefficient before adding the user feature to the time-related feature and the normalized amplitude-related feature, and
wherein the time-related coefficient, the amplitude-related coefficient, and the user coefficient are determined by a calibration process comprising measuring the blood pressure of the user with an independent sensor.

2. Method according to claim 1 , wherein the blood pressure function is linear with respect to the time-related feature and the normalized amplitude-related feature.

3. Method according to claim 1 , wherein the user feature comprises one or a combination of:
gender;
age;
body mass index; or
height.

4. Method according to claim 1 , wherein the first and second features used for calculating the blood pressure value are automatically determined from a plurality of features.

5. Method according to claim 1 , wherein the time related feature is based on one or a combination of:
time to first peak;
time to second peak;
inverse time to first peak;
inverse of time to second peak,
time between first and second peak,
time to reflection,
ejection duration, or
heart rate.

6. Method according to claim 1 , wherein the normalized amplitude-related feature is based on one or a combination of:
a normalized end-systolic pressure;
an augmentation index; or
a normalized ejection area.

7. Method according to claim 1 ,
wherein said time-related feature and said normalized amplitude-related feature are calculated from the selected only one pulse,
wherein a weighting factor is calculated for the selected only one pulse on the basis of an error of the selected only one pulse relative to an average of the plurality of pulses, and
wherein the blood pressure function calculates the blood pressure value on the basis of a weighted combination, wherein the time-related feature and the normalized amplitude-related feature of each pulse is weighted with the weighting factor.

8. Method according to claim 7 , wherein the weighting factor of the selected only one pulse is calculated on the basis of a match between a morphology of the selected only one pulse and a typical morphology.

9. Method according to claim 1 , wherein the step of providing the pulsatility signal comprises the step of measuring the pulsatility signal.

10. Method according to claim 9 , wherein the pulsatility signal is measured on the basis of one of a photoplethysmogram, an impedance sensor, an implantable accelerometer sensor, an implantable optical sensor, an implantable impedance sensor or an invasive arterial sensor.

11. A non-transitory computer-readable medium having instructions thereon that when implemented by a processor cause the processor to perform a method comprising:
providing a pulsatility signal of a user, the pulsatility signal comprising a plurality of pulses;
selecting only one pulse of the plurality of pulses of the pulsatility signal;
for the selected only one pulse, determining a time-related feature comprising a time duration within the selected only one pulse and a normalized amplitude-related feature, on the basis of the pulsatility signal; and
calculating a blood pressure value on the basis of a blood pressure function depending on the time-related feature, the normalized amplitude-related feature, and function parameters,
wherein the calculating does not use a non-normalized amplitude-related feature,
wherein the normalized amplitude-related feature is an amplitude-related feature normalized by another amplitude-related feature,
wherein the blood pressure function further linearly depends on a user feature,
wherein the function parameters comprise a time-related coefficient, an amplitude-related coefficient, and a user coefficient,
wherein the time-related feature is multiplied with the time-related coefficient, the normalized amplitude-related feature is multiplied with the amplitude-related coefficient before summing the time-related feature with the normalized amplitude-related feature,
wherein the user feature is multiplied with the user coefficient before adding the user feature to the time-related feature and the normalized amplitude-related feature, and
wherein the time-related coefficient, the amplitude-related coefficient, and the user coefficient are determined by a calibration process comprising measuring the blood pressure of the user with an independent sensor.

12. Apparatus for determining a blood pressure value comprising:
at least one processor configured to:
receive data representing a pulsatility signal of a user, the pulsatility signal comprising a plurality of pulses;
select only one pulse of the plurality of pulses of the pulsatility signal;
calculate a first feature for the selected only one pulse;
calculate a second feature for the selected only one pulse; and
calculate a blood pressure value on the basis of a function depending on the first feature, the second feature, and function parameters, the first feature being a time-related feature comprising a time duration within the selected only one pulse, and the second feature being a normalized amplitude-related feature,
wherein the blood pressure value is not calculated based on a non-normalized amplitude-related feature,
wherein the normalized amplitude-related feature is an amplitude-related feature normalized by another amplitude-related feature,
wherein the blood pressure function further linearly depends on a user feature,
wherein the function parameters comprise a time-related coefficient, an amplitude-related coefficient, and a user coefficient,
wherein the time-related feature is multiplied with the time-related coefficient, the normalized amplitude-related feature is multiplied with the amplitude-related coefficient before summing the time-related feature with the normalized amplitude-related feature,
wherein the user feature is multiplied with the user coefficient before adding the user feature to the time-related feature and the normalized amplitude-related feature, and
wherein the time-related coefficient, the amplitude-related coefficient, and the user coefficient are determined by a calibration process comprising measuring the blood pressure of the user with an independent sensor.

Assignees

• Csem Ct Suisse Delectronique Microtechnique Sa Rech Developpement
• Csem Centre Suisse Delectronique Et De Microtechnique Sa—Recherche Et Dev

Inventors

• Proença Martin
• Sola I Caros Josep
• Lemay Mathieu
• Verjus Christophe

Classifications

• A61B5/02116 Primary

  of pulse wave amplitude (A61B5/02225 takes precedence) · CPC title

• A61B5/02125

  of pulse wave propagation time · CPC title

• A61B5/02154

  by optical transmission · CPC title

• A61B5/02156

  Calibration means · CPC title

• A61B5/02416

  using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence) · CPC title