Minute ventilation estimation based on depth maps

• US 8,971,985 B2
• Filed: 06/01/2012
• Issued: 03/03/2015
• Est. Priority Date: 06/01/2012
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Bernal, Edgar A., Mestha, Lalit Keshav, Xu, Beilei
• Primary Examiner(s): Chen, Tse
• Assistant Examiner(s): Brutus, Joel F
• Application Number:
  US13/486,682
• Publication Number:
  US 20130324830A1
• Time in Patent Office: 1,005 Days
• Field of Search: 600/407, 600/411, 600/427
• US Class Current: 600/407
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/1128 using image analysis A61B5/1127 takes precedence
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: G06T 2207/10152 Varying illumination
• CPC Class Codes: G06T 2207/30004 Biomedical image processing
• CPC Class Codes: G06T 2207/30076 Plethysmography
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

What is disclosed is a system and method for estimating minute ventilation by analyzing distortions in reflections of structured illumination patterns captured in a video of a thoracic region of a subject of interest being monitored for respiratory function. Measurement readings can be acquired in a few seconds under a diverse set of lighting conditions and provide a non-contact approach to patient respiratory function that is particularly useful for infant care in an intensive care unit (ICU), sleep studies, and can aid in the early detection of sudden deterioration of physiological conditions due to detectable changes in chest volume. The systems and methods disclosed herein provide an effective tool for non-contact minute ventilation estimation and respiratory function analysis.

Claims

1. A method for estimating minute ventilation from video captured of a subject of interest being monitored for respiratory function in a remote sensing environment, the method comprising:

receiving a video of a target area of a thoracic region of a subject of interest being monitored for respiratory function; and

processing said video to obtain a depth map at inspiration and expiration within a same breathing cycle for a plurality of breathing cycles over time, comprising;

comparing images of said video to known spatial characteristics of undistorted projected patterns such that a spatial distortion of said patterns can be characterized, said spatial distortion having been introduced by a reflection of said patterns off a surface of said target area;

calculating depth maps D_i and D_m from said spatial distortion, where D_i and D_m are calculated at a maximum inspiration and a maximum expiration, respectively, said depth maps D_i and D_m having a same dimension in pixels; and

estimating minute ventilation for said subject, comprising;

2. The method of claim 1, wherein said video is captured using a video camera and an illuminator projecting a pattern of structured illumination, said video camera being, at least in part, sensitive to electromagnetic radiation in a wavelength range overlapping with a wavelength of projected structured illumination to capture video of said subject.

3. The method of claim 2, wherein said video camera has at least one channel operating in any of:

a visible and IR wavelength bands, that is in a same wavelength band of said structured illumination.

4. The method of claim 1, wherein said video is captured using at least two video cameras having partially overlapping fields of view, with each including at least a partial view of said target area.

5. The method of claim 1, wherein said target area contains at least a partial view of any of:

an anterior thoracic region of said subject, a back region of said subject'"'"'s dorsal body, and a side view of said thoracic region.

6. The method of claim 1, further comprising monitoring incremental changes in said minute ventilation for an occurrence of any of:

PUHD Type I and PUHD Type II.

7. The method of claim 1, wherein said video is captured using a video camera and an illuminator projecting a pattern of structured illumination, said video camera being, at least in part, sensitive to electromagnetic radiation in a wavelength range overlapping with a wavelength of projected structured illumination to capture video of said subject.

8. The method of claim 7, wherein said video camera has at least one channel operating in any of visible or IR wavelength bands that is in a same wavelength band of said structured illumination.

9. The method of claim 1, wherein said target area contains at least a partial view of any of:

an anterior thoracic region of said subject, a back region of said subject'"'"'s dorsal body, and a side view of said thoracic region.

10. The method of claim 1, further comprising monitoring incremental changes in said minute ventilation for an occurrence of any of:

PUHD Type I and PUHD Type II.

11. A system for estimating-minute ventilation from video captured of a subject of interest being monitored for respiratory function in a remote sensing environment, the system comprising:

a memory; and

a processor in communication with said memory, said processor executing machine readable instructions for performing the steps of;

receiving a video of a target area of a thoracic region of a subject of interest being monitored for respiratory function;

processing said video to obtain a depth map at inspiration and expiration within a same breathing cycle for a plurality of breathing cycles over time, comprising;

comparing images of said video to known spatial characteristics of undistorted projected patterns such that a spatial distortion of said patterns can be characterized, said spatial distortion having been introduced by a reflection of said patterns off a surface of said target area;

calculating depth maps D_i and D_m from said spatial distortion, where D_i and D_m are calculated at a maximum inspiration and a maximum expiration, respectively, said depth maps D_i and D_m having a same dimension in pixels; and

estimating minute ventilation for said subject, comprising;

12. The system of claim 11, wherein said video is captured using a video camera and an illuminator projecting a pattern of structured illumination, said video camera being, at least in part, sensitive to electromagnetic radiation in a wavelength range overlapping with a wavelength of projected structured illumination to capture video of said subject.

13. The system of claim 12, wherein said video camera has at least one channel operating in any of visible or IR wavelength bands that is in a same wavelength band of said structured illumination.

14. The system of claim 12, wherein said video has at least one channel operating in any of:

a visible and IR wavelength bands, that is in a same wavelength band of said structured illumination.

15. The system of claim 11, wherein said target area contains at least a partial view of any of:

an anterior thoracic region of said subject, a back region of said subject'"'"'s dorsal body, and a side view of said thoracic region.

16. The system of claim 11, wherein said video is captured using a video camera and an illuminator projecting a pattern of structured illumination, said video camera being, at least in part, sensitive to electromagnetic radiation in a wavelength range overlapping with a wavelength of projected structured illumination to capture video of said subject.

17. The system of claim 11, wherein said video is captured using at least two video cameras having partially overlapping fields of view, with each including at least a partial view of said target area.

18. The system of claim 11, wherein said target area contains at least a partial view of any of:

an anterior thoracic region of said subject, a back region of said subject'"'"'s dorsal body, and a side view of said thoracic region.

19. The system of claim 11, further comprising monitoring incremental changes in said minute ventilation for an occurrence of any of:

PUHD Type I and PUHD Type II.

20. A method for estimating-minute ventilation from video captured of a subject of interest being monitored for respiratory function in a remote sensing environment, the method comprising:

receiving a video of a target area of a thoracic region of a subject of interest being monitored for respiratory function; and

processing said video to obtain a depth map at inspiration and expiration within a same breathing cycle for a plurality of breathing cycles over time, comprising;

comparing images of said video to known spatial characteristics of undistorted projected patterns such that a spatial distortion of said patterns can be characterized, said spatial distortion having been introduced by a reflection of said patterns off a surface of said target area;

calculating depth maps D_i and D_m from said spatial distortion, where D_i and D_m are calculated at a maximum inspiration and a maximum expiration, respectively, said depth maps D_i and D_m having a same dimension in pixels; and

estimating minute ventilation for said subject, comprising;