METHOD AND DEVICE FOR ASCERTAINING A BLOOD PRESSURE CURVE

• US 20180146865A1
• Filed: 05/12/2016
• Published: 05/31/2018
• Est. Priority Date: 05/29/2015
• Status: Active Grant

• Current Assignee: CiS Forschungsinstitut für Mikrosensorik GmbH
• Original Assignee: CiS Forschungsinstitut für Mikrosensorik GmbH
• Inventors: ORTLEPP, Hans-Georg
• Granted Patent: US 10,362,945 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

The invention relates to a method and a device for ascertaining a time-dependent blood pressure curve. Time- and volume-dependent blood flow values are detected in a noninvasive manner in a tissue section with a good blood flow as photoplethysmography values P(t) using a photoplethysmography sensor. A data processing unit transforms the photoplethysmography values P(t) into blood pressure values B(t) by carrying out a transformation rule. An output and storage unit at least temporarily stores the transformed blood pressure values B(t) as time-dependent blood pressure values and transfers said values to an external or internal display and/or storage unit arranged downstream.

Claims

1. A method for ascertaining the time-dependent curve of the blood pressure including the following steps:

noninvasive detection of time-dependent and volume-dependent blood flow values, in the form of photoplethysmographic values P(t), in a section of tissue with good blood circulation by means of a photoplethysmographically functioning sensor;

transformation of the photoplethysmographic values P(t) into blood pressure values B(t) through the use of the following transformation formula;

2. The method according to claim 1, wherein

digitized photoplethysmographic values P_i with N measurement points and i=1 . . . N are generated,

the first and second derivatives are generated as difference quotients:

3. The method according to claim 1, wherein the photoplethysmographic values P(t) are detected in the outer ear canal, preferably on the inside of the tragus.

4. The method according to claim 1, wherein the coefficients are established by means of a calibration measurement, either for an individual patient or for a group of patients.

5. The method according to claim 1, wherein within a signal period, the time interval between the occurrence of the first of the two peaks in the curve of the transformed blood pressure values B(t) and a warning signal is generated if the interval falls below a predetermined minimum time interval in order to signal a critical blood pressure.

18. The method according to claim 2 wherein the photoplethysmographic values P(t) are detected in the outer ear canal, preferably on the inside of the tragus.

19. The method according to claim 2 wherein the coefficients are established by means of a calibration measurement, either for an individual patient or for a group of patients.

20. The method according to claim 3 wherein the coefficients are established by means of a calibration measurement, either for an individual patient or for a group of patients.

6. A device for ascertaining the time-dependent curve of the blood pressure, including:

a photoplethysmographic sensor, which noninvasively detects time-dependent and volume-dependent blood flow values, in the form of photoplethysmographic values P(t), in a section of tissue with good blood circulation;

a data processing unit, which transforms the photoplethysmographic values P(t) into blood pressure values B(t), by executing the following transformation instruction;

7. The device according to claim 6, wherein the photoplethysmographic sensor is selected from the following group:

an ear sensor, which detects the photoplethysmographic values P(t) in the outer ear canal, preferably on the tragus; and

a fingertip sensor, which detects the photoplethysmographic values P(t) at a fingertip.

8. The device according to claim 6, wherein an FIR filter is implemented in the data processing unit.

9. The device according to claim 6, wherein it includes a signal output unit, which issues a warning signal if the time interval between the occurrences of the first of the two peaks in the curve of the transformed blood pressure values B(t) falls below a predetermined minimum time interval.

11. The device according to claim 7, wherein an FIR filter is implemented in the data processing unit.

12. The device according to claim 7, wherein it includes a signal output unit, which issues a warning signal if the time interval between the occurrences of the first of the two peaks in the curve of the transformed blood pressure values B(t) falls below a predetermined minimum time interval.

13. The device according to claim 8, wherein it includes a signal output unit, which issues a warning signal if the time interval between the occurrences of the first of the two peaks in the curve of the transformed blood pressure values B(t) falls below a predetermined minimum time interval.

10. (canceled)

14-17. -17. (canceled)