System and methods for video-based monitoring of vital signs

Patent metadata

Field	Value
Publication number	US-11317828-B2
Application number	US-202016888011-A
Country	US
Kind code	B2
Filing date	May 29, 2020
Priority date	Feb 19, 2016
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

The present invention relates to the field of medical monitoring, and in particular non-contact, video-based monitoring of pulse rate, respiration rate, motion, and oxygen saturation. Systems and methods are described for capturing images of a patient, producing intensity signals from the images, filtering those signals to focus on a physiologic component, and measuring a vital sign from the filtered signals.

First claim

What is claimed is:

1. A video-based method of measuring a patient's vital sign, comprising:
receiving a video signal from a video camera, the video signal having a field of view;
extracting from the video signal two or more time-varying color signals in the field of view;
identifying a frequency content of each time-varying color signal;
combining at least two time-varying color signals having a shared frequency content;
calculating a statistic of the combined signal, wherein the statistic comprises an amplitude, a variability, a skew, or a signal to noise ratio;
measuring a vital sign from the combined signal; and
determining a weight for the vital sign, the weight being based on the statistic, and adding the vital sign to a running average based on the weight.

2. The method of claim 1 , wherein combining comprises averaging the at least two time-varying color signals.

3. The method of claim 1 , wherein the vital sign comprises heart rate.

4. The method of claim 3 , wherein measuring the heart rate comprises accumulating frequency peaks from the combined signal, selecting a median frequency, and updating a running average heart rate from the selected frequency.

5. The method of claim 1 , further comprising applying a weight to the combined signal prior to measuring the vital sign from the combined signal, the weight being based on the statistic.

6. The method of claim 1 , wherein extracting the time-varying color signal comprises extracting two time-varying color signals from a region within the field of view, and wherein measuring the vital sign comprises measuring oxygen saturation from the two time-varying color signals.

7. The method of claim 1 , wherein each time-varying color signal extracted from the video signal is from a distinct region and wherein combining at least two time-varying color signals having a shared frequency content comprises combining at least two time-varying color signals having a shared frequency content that from non-adjacent regions.

8. A video-based method of measuring a patient's vital sign, comprising:
generating a video signal from a video camera having a field of view;
extracting from the video signal a plurality of time-varying intensity signals;
combining at least two time-varying intensity signals from a first region of the field of view to produce a first combined intensity signal;
measuring a first vital sign of the patient from the first combined intensity signal;
combining at least two time-varying intensity signals from a second region of the field of view to produce a second combined intensity signal; and
measuring a second vital sign of the patient from the second combined intensity signal.

9. The method of claim 8 , wherein the first region is selected based on intensity signals comprising a first modulation at a first shared frequency, and the second region is selected based on intensity signals comprising a second modulation at a second shared frequency, the first shared frequency being different from the second shared frequency.

10. The method of claim 8 , wherein the first vital sign is heart rate and the second vital sign is respiration rate.

11. The method of claim 8 , further comprising displaying the image signal on a display, highlighting on the display the first region for the first vital sign, and highlighting on the display the second region for the second vital sign.

12. The method of claim 9 , wherein the first modulation at the first shared frequency is above an amplitude threshold.

13. The method of claim 8 , wherein extracting the plurality of intensity signal comprises extracting at least one red intensity signal comprising a time-varying average of red values, at least one green intensity signal comprising a time-varying average of green values, and at least one blue intensity signal comprising a time-varying average of blue values.

14. A camera-based method of measuring a patient's vital sign, comprising:
receiving an image signal from a camera having a field of view;
receiving a user input identifying a region in the image signal;
measuring a first vital sign of the patient, comprising:
from the region, selecting a first set of pixels that exhibit a first modulation at a first shared frequency, wherein the first selected pixels are non-contiguous; and
measuring the first vital sign of the patient from the selected first pixels;

displaying a number derived from the first measured vital sign; and
triggering an alarm based on the displayed number and stored alarm conditions, wherein the stored alarm conditions omit a sensor-off or sensor-disconnect alarm.

15. The method of claim 14 , further comprising:
measuring and outputting a second vital sign of the patient, comprising:
from the region, selecting a second set of pixels that exhibit a second modulation at a second shared frequency different from the first shared frequency, wherein the second selected pixels are non-contiguous; and
measuring the second vital sign of the patient from the selected second pixels.

16. The method of claim 14 , wherein the first vital sign comprises heart rate and the second vital sign comprises respiration rate.

17. The method of claim 14 , further comprising receiving a second user input moving the region to a new location, and subsequently measuring the first vital sign from the new location.

18. The method of claim 14 , wherein the alarm is a system-level alarm, a physiologic alarm, or both.

19. A video-based method of measuring a patient's vital sign, comprising:
receiving a video signal from a video camera, the video signal having a field of view that includes exposed skin of a patient;
extracting from the video signal a time-varying amplitude signal for each of a plurality of regions, each region including exposed skin of the patient;
identifying a frequency content of each amplitude signal;
selecting two or more non-adjacent regions that have a shared frequency content comprising a modulation at a shared frequency, wherein each of the two or more non-adjacent regions satisfy a quality criterion, the quality criterion comprising a signal to noise ratio that satisfies a threshold, or a skew value that satisfies a threshold;
combining the amplitude signals of the selected regions;
measuring a vital sign from the combined signal; and
outputting the vital sign for further processing or display.

20. The method of claim 19 , further comprising removing an amplitude signal from the combined signal upon failure of the removed amplitude signal to satisfy the criterion.

Assignees

• Covidien Lp

Inventors

• Addison Paul S
• Foo David
• Jacquel Dominique

Classifications

• A61B5/7485

  Automatic selection of region of interest · CPC title

• A61B5/6843

  Monitoring or controlling sensor contact pressure · CPC title

• A61B5/14551

  for measuring blood gases · CPC title

• A61B5/7425

  Displaying combinations of multiple images regardless of image source, e.g. displaying a reference anatomical image with a live image · CPC title

• A61B5/1032 Primary

  Determining colour of tissue for diagnostic purposes · CPC title