Photoplethysmographic device for measuring a heart rhythm

• US 9,826,912 B2
• Filed: 10/19/2016
• Issued: 11/28/2017
• Est. Priority Date: 11/11/2015
• Status: Active Grant

• Current Assignee: Livassured BV
• Original Assignee: Livassured BV
• Inventors: Ungureanu, Constantin, Tielens, Theo Ary Asmund
• Primary Examiner(s): Gedeon, Brian T
• Application Number:
  US15/297,481
• Publication Number:
  US 20170127958A1
• Time in Patent Office: 405 Days
• Field of Search: None
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

Abstract

Photoplethysmographic device for measuring a heart rhythm, comprising a housing having a contacting surface and a control unit, a photoplethysmographic sensor mechanically attached to the contacting surface and connected to the control unit, wherein the control unit is arranged to receive a photoplethysmographic signal from the photoplethysmographic sensor, a fastening band having a first end and a second end, the first end and second end attached to the device for attaching the device to a subject with the contacting surface contacting the subject'"'"'s skin, a pressure sensor attached to the contacting surface in close proximity to the photoplethysmographic sensor. The control unit is arranged determining whether the pressure from the pressure sensor is in a range suitable for photoplethysmographic measurement by the photoplethysmographic sensor.

Claims

1. Photoplethysmographic device for measuring a heart rhythm, comprising a housing having a contacting surface and a control unit;

a photoplethysmographic sensor mechanically mounted to the contacting surface and connected to the control unit, wherein the control unit is arranged to receive a photoplethysmographic signal from the photoplethysmographic sensor, wherein the control unit is arranged for determining a heart rhythm from the photoplethysmographic signal;

a fastening band having a first end and a second end, the first end and second end attached to the device for attaching the device to a subject with the contacting surface contacting the subject'"'"'s skin;

a pressure sensor mounted to the contacting surface in close proximity to the photoplethysmographic sensor;

wherein the control unit is arranged for determining whether the pressure from the pressure sensor is in a range suitable for photoplethysmographic measurement by the photoplethysmographic sensor, wherein the control unit is arranged for;

determining a reliability factor for the PPG measurements from the pressure signal; and

determining a heart rhythm using an actual photoplethysmographic measurement and a running history of measurements of the photoplethysmographic signal; and

wherein a measurement of the photoplethysmographic signal is saved in the running history when the reliability factor is higher than a threshold.

2. Photoplethysmographic device according to claim 1, wherein the control unit is arranged for comparing a pressure signal strength from the pressure sensor with a first threshold value.

3. Photoplethysmographic device according to claim 1, wherein the control circuit is further arranged for comparing the pressure signal strength from the pressure sensor with a second threshold value, the second threshold value being higher than the first threshold value.

4. Photoplethysmographic device according to claim 3, further comprising an indicator connected to the control unit, wherein the control unit is arranged for activating the indicator when the pressure signal strength from the pressure sensor is equal to or exceeds the first threshold value and the pressure signal strength is equal to or less than the second threshold value.

5. Photoplethysmographic device according to claim 4, wherein the indicator is a sound alarm.

6. Photoplethysmographic device according to claim 1, wherein the photoplethysmographic sensor has a light source, and wherein the control unit is arranged for:

comparing the pressure signal strength with a third threshold value; and

wherein the control unit is arranged for deactivating the light source in the photoplethysmographic sensor when the pressure signal strength from the pressure sensor is equal to or less than the third threshold value.

7. Pressure sensor according to claim 6, wherein the control unit is arranged for deactivating the light source in the photoplethysmographic sensor when the pressure signal strength from the pressure sensor is equal to or greater than the second threshold value.

8. Photoplethysmographic device according to claim 1, wherein at least one of the photoplethysmographic sensor and the pressure sensor are mounted flush with the contacting surface.

9. Photoplethysmographic device according to claim 2, wherein the control circuit is further arranged for comparing the pressure signal strength from the pressure sensor with a second threshold value, the second threshold value being higher than the first threshold value.

10. Photoplethysmographic device according to claim 9, further comprising an indicator connected to the control unit, wherein the control unit is arranged for activating the indicator when the pressure signal strength from the pressure sensor is equal to or exceeds the first threshold value and the pressure signal strength is equal to or less than the second threshold value.

11. Photoplethysmographic device according to claim 5, wherein the indicator is a sound alarm.