SYSTEMS AND METHODS FOR DETECTING PULSE WAVE VELOCITY

• US 20160120411A1
• Filed: 10/15/2015
• Published: 05/05/2016
• Est. Priority Date: 10/30/2014
• Status: Active Grant

• Current Assignee: Stryker Corporation
• Original Assignee: Stryker Corporation
• Inventors: Kostic, Marko N., Mix, Joshua Elmer, Hopper, Christopher John, Hadley, Sean
• Granted Patent: US 10,820,859 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/6833 Adhesive patches

Abstract

A non-invasive sensor unit adapted to be coupled to a patient includes a pair of light emitters spaced apart a known distance, and a pair light detectors. The light detectors detect light emitted from the emitters and scattered by a patient. The unit determines one or more cardiovascular characteristics of the patient from the scattered light, such as the patient'"'"'s pulse wave velocity; a saturation of peripheral oxygen (SpO₂) level; a temperature; a respiration rate; a heart rate; and a blood pressure. The light emitters emit light that may have wavelengths between 600 and 1000 nanometers. The unit, in some embodiments, is integrated into a patch adapted to be secured to the skin of the patient. Readings from the unit may be transmitted to a separate device spaced from the unit, such as via Bluetooth, WiFi, or by other means.

Claims

1. A sensor unit adapted to be non-invasively coupled to a patient, the sensor unit comprising:

a first light emitter,

a plurality of first light detectors, the plurality of first light detectors adapted to detect a portion of first light that is emitted by the first light emitter and scattered by the patient;

a second light emitter spaced from the first light emitter a known distance;

a plurality of second light detectors, the plurality of second light detectors adapted to detect a portion of second light emitted by the second light emitter and scattered by the patient; and

a controller in communication with the plurality of first light detectors and with the plurality of second light detectors, the controller adapted to determine a pulse wave velocity of the patient using the known distance and an output from at least one of the plurality of first light detectors and an output from at least one of the plurality of second light detectors.

2. The sensor unit of claim 1 wherein the plurality of first light detectors are positioned at different distances from the first light emitter, and wherein the plurality of second light detectors are positioned at different distances from the second light emitter.

3. The sensor unit of claim 2 wherein the controller is adapted to select at least one of the plurality of first light detectors and at least one of the plurality of second light detectors based upon how deep into the patient the pulse wave velocity determination is to be based.

4. The sensor unit of claim 1 wherein the plurality of first light detectors includes a first subset of first light detectors positioned a first distance from the first light emitter and a second subset of first light detectors positioned a second distance from the first light emitter;

and wherein the plurality of second light detectors includes a third subset of second light detectors positioned the first distance from the second light emitter and a fourth subset of second light detectors positioned the second distance from the second light emitter.

5. The sensor unit of claim 4 wherein the controller selects one of the first and second subsets based upon how deep into the patient the pulse wave velocity determination is to be based, the controller using the selected subset in determining the pulse wave velocity.

6. The sensor unit of claim 5 wherein the controller selects at least one of the first light detectors from the selected first or second subset based upon an orientation of the sensor unit relative to the patient'"'"'s adjacent arterial structure, the controller using the selected at least one of the first light detectors in determining the pulse wave velocity.

7. The sensor unit of claim 1 further including a transmitter, the transmitter adapted to transmit the pulse wave velocity to at least one of the following:

a cell phone, a computer, a patient support apparatus, and a local area network.

8. The sensor unit of claim 1 wherein the controller is adapted to repetitively determine the pulse wave velocity of the patient.

9. The sensor unit of claim 8 wherein the controller is further adapted to detect changes in the pulse wave velocity of the patient over time.

10. The sensor unit of claim 1 wherein the first light and second light have wavelengths between 600 and 1000 nanometers.

11. The sensor unit of claim 1 wherein the controller is further adapted to measure at least one of the following patient conditions:

a saturation of peripheral oxygen (SpO₂) level;

a temperature;

a respiration rate;

a heart rate; and

a blood pressure.

12. The sensor unit of claim 1 wherein the first and second light emitters and the pluralities of first and second light detectors are all integrated into a surface of one of a mattress and a cushion.

13. The sensor unit of claim 1 wherein the first and second light emitters, the controller, and the pluralities of first and second light detectors are all integrated into a patch adapted to be secured to the skin of the patient.

14. The sensor unit of claim 1 wherein the first light emitter, the plurality of first light detectors, the second light emitter, and the plurality of second light detectors are all integrated into a common housing.

15. A method of evaluating a patient comprising:

(a) providing a sensor unit having a first light emitter, a first light detector, a second light emitter, and a second light detector, the first light emitter being spaced apart from the second light emitter a known distance;

(b) attaching the sensor unit to the patient;

(c) emitting first light from the first light emitter and detecting a portion of the first light that is scattered by the patient using the first light detector;

(d) emitting second light from the second light emitter and detecting a portion of the second light that is scattered by the patient using the second light detector;

(e) estimating a first arterial stiffness using outputs from the first and second light detectors during steps (c) and (d);

(f) repeating at least steps (c) through (d) and estimating a second arterial stiffness using outputs from the first and second light detectors during the repeated steps (c) and (d); and

(g) comparing the first and second estimates of arterial stiffness.

16. The method of claim 15 further including displaying information indicating an increase or decrease in the arterial stiffness over time, the information being based at least partially on the first and second estimates of arterial stiffness.

17. The method of claim 15 further including determining a first pulse wave velocity using the outputs of the first and second light detectors during steps (c) and (d);

and determining a second pulse wave velocity using the outputs of the first and second light detectors during the repeated steps (c) and (d).

18. The method of claim 15 wherein the first light emitter, first light detector, second light emitter, and second light detector are all integrated into a common housing.

19. The method of claim 15 wherein the first light and second light have wavelengths between 600 and 1000 nanometers.

20. The method of claim 15 wherein the sensor unit is coupled to an adhesive patch and the step of attaching the sensor unit to the patient includes securing the adhesive patch to the skin of the patient.

21. The method of claim 20 further including measuring at least one of the following patient conditions with the sensor unit:

a saturation of peripheral oxygen (SpO₂) level;

a temperature;

a respiration rate;

a heart rate; and

a blood pressure.

22. The method of claim 20 further including providing a controller physically coupled to the adhesive patch, the controller configured to estimate the first arterial stiffness by analyzing the outputs from the first and second light detectors during steps (c) and (d).

23. A sensor unit adapted to be non-invasively coupled to a patient, the sensor unit comprising:

a first light emitter,

a first light detector, the first light detector adapted to detect a portion of first light that is emitted by the first light emitter and scattered by the patient;

a second light emitter spaced from the first light emitter a known distance;

a second light detector, the second light detector adapted to detect a portion of second light emitted by the second light emitter and scattered by the patient,

a housing;

a transmitter contained within the housing, the transmitter adapted to transmit data generated from the first and second light detectors to a remote device; and

a patch physically coupled to the housing, the patch adapted to secure the first light emitter, the first light detector, the second light emitter, and the second light detector to the skin of the patient.