CAPILLARY REFILL TIME DIAGNOSTIC APPARATUS AND METHODS

• US 20130211216A9
• Filed: 12/23/2010
• Published: 08/15/2013
• Est. Priority Date: 12/24/2009
• Status: Active Grant

• Current Assignee: Children's Medical Center Corporation
• Original Assignee: Children's Medical Center Corporation
• Inventors: Bezzerides, Vassilios, Neuman, Mark Ian
• Granted Patent: US 9,603,559 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/0053 by applying pressure, e.g. compression, indentation, palpation, grasping, gauging
• CPC Class Codes: A61B 5/0055 by applying suction
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/683 Means for maintaining contact with the body A61B5/6802 takes precedence
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

An apparatus for measuring capillary refill time has a measurement module containing at least two radiation sources and at least one detector configured to detect radiation from each source that interacts with and is received from a measurement region of a patient or subject. One radiation source may be characterized by a wavelength that is absorbed substantially equally by oxyhemoglobin and deoxyhemoglobin. The other radiation source may be substantially unaffected by the presence or absence of blood in the measurement region. The measurement module may be applied against a measurement region of a patient for a first time period, and the released from the measurement region for a second time period, and detected signals processed to quantitatively evaluate capillary refill time.

Claims

1. An apparatus for measuring capillary refill time comprising:

at least one source for emitting first radiation characterized by a first wavelength and for emitting second radiation characterized by a second wavelength, wherein the first source and second source are configured to illuminate a measurement region on a body and the first radiation is absorbed substantially equally by an amount of oxyhemoglobin or the same amount of deoxyhemoglobin.

2. The apparatus of claim 1, further comprising:

means to momentarily exclude blood from or reduce blood flow to the measurement region;

means to detect first and second radiations received from the measurement region; and

electronic means to process signals representative of detected first and second radiations for determining capillary refill time and/or capillary refill rate.

5. The apparatus of claim 1, further comprising:

at least one detector for detecting the first radiation received from the measurement region and providing a first signal representative of the first radiation received from the measurement region and for detecting the second radiation received from the measurement region and providing a second signal representative of the second radiation received from the measurement region; and

at least one processor configured to calculate a ratio signal from the first signal and second signal.

6. The apparatus of claim 5 wherein the at least one processor is further configured to determine a capillary refill time based upon a first derivative or second derivative of the ratio signal.

3-4. -4. (canceled)

7. (canceled)

8. An apparatus for measuring capillary refill time comprising:

at least one source for emitting first radiation characterized by a first wavelength and for emitting second radiation characterized by a second wavelength;

at least one detector for detecting the first radiation and the second radiation; and

a probe including a convex surface configured to be controllably applied against and released from a measurement region including a capillary bed, wherein the at least one source is configured to radiate the measurement region and the at least one detector is configured to detect the first radiation and the second radiation received from the measurement region.

9. The apparatus of claim 8, wherein the convex surface is configured to be applied against the measurement region to exclude blood from the capillary bed and to be controllably released from the measurement region to allow perfusion of blood into the capillary bed.

10. The apparatus of claim 8 wherein the second radiation is substantially unaffected by the presence or absence of blood in the measurement region and the second wavelength is in a range between about 600 nm and about 750 nm.

13. The apparatus of claim 8, wherein the first radiation is absorbed substantially equally by an amount of oxyhemoglobin or the same amount of deoxyhemoglobin and the first wavelength is in a range between about 500 nm and about 550 nm.

17. The apparatus of claim 13, wherein at least a portion of the probe comprising the convex surface is transparent to the first radiation and second radiation.

18. The apparatus of claim 17, wherein the at least one source is configured to emit first and second radiations through the at least a portion of the probe and the at least one detector is configured to detect the first radiation and/or second radiation returned through the at least a portion of the probe.

19. The apparatus of claim 17, wherein the at least a portion of the probe comprising the convex surface is configured to at least partially collimate or at least partially focus the first radiation and/or the second radiation.

22. The apparatus of claim 13, further comprising a controller configured to:

cause the at least one source to emit first and second radiations during at least one first period;

calculate first ratios, for a first plurality of times during the at least one first period, of first signals and second signals from the at least one detector, wherein each one of the first signals is representative of an amount of the first radiation received from the measurement region and each one of the second signals is representative of an amount of the second radiation received from the measurement region at a respective one of the first plurality of times;

identify an end to the at least one first period based on a first trend in the first ratios or a value of one of the first ratios;

cause the at least one source to emit first and second radiations during at least one second period;

calculate second ratios, for a second plurality of times during the at least one second period, of third signals and fourth signals from the at least one detector, wherein each one of the third signals is representative of an amount of the first radiation received from the measurement region and each one of the fourth signals is representative of an amount of the second radiation received from the measurement region at a respective one of the second plurality of times; and

calculate a capillary refill time based on a second trend of the second ratios or a value of one of the second ratios.

11-12. -12. (canceled)

14-16. -16. (canceled)

20-21. -21. (canceled)

23-26. -26. (canceled)

27. A method for measuring capillary refill time comprising:

emitting, by a first source, first radiation characterized by a first wavelength onto a measurement region including a capillary bed;

emitting, by a second source, second radiation characterized by a second wavelength onto the measurement region;

detecting, by at least one detector, the first radiation and the second radiation received from the measurement region;

controllably applying and releasing a convex surface of a probe against the measurement region;

calculating a value representative of a ratio of the first radiation and the second radiation received from the measurement region.

28. The method of claim 27, wherein the first radiation is absorbed substantially equally by an amount of oxyhemoglobin or the same amount of deoxyhemoglobin.

29. The method of claim 28, wherein the first wavelength is in a range between about 500 nm and about 550 nm, and the second wavelength is in a range between about 600 nm and about 750 nm.

30. The method of claim 28, further comprising modulating any one of or a combination of:

the first source, the second source and the at least one detector.

33. The method of claim 28, further comprising:

applying the convex surface against the measurement region to momentarily exclude blood from the capillary bed; and

releasing the convex surface from the measurement region to allow perfusion of blood into the capillary bed.

34. The method of claim 28, wherein

the emitting the first radiation comprises emitting the first radiation through at least a transparent portion of the convex surface;

the emitting the second radiation comprises emitting the second radiation through at least a transparent portion of the convex surface; and

the detecting the first radiation and the second radiation comprises detecting the first radiation and/or the second radiation through at least a transparent portion of the convex surface.

37. The method of claim 28, further comprising:

emitting respective radiations from the first source and second source during at least one first period;

calculating first ratios by at least one processor, for a first plurality of times during the at least one first period, of first signals and second signals from the at least one detector, wherein each one of the first signals is representative of an amount of the first radiation received from the measurement region and each one of the second signals is representative of an amount of the second radiation received from the measurement region at a respective one of the first plurality of times;

identifying, by the at least one processor, an end to the at least one first period based on a first rend in the first ratios or a value of one of the first ratios;

emitting respective radiations from the first source and second source during at least one second period;

calculating second ratios by the at least one processor, for a second plurality of times during the at least one second period, of third signals and fourth signals from the at least one detector, wherein each one of the third signals is representative of an amount of the first radiation received from the measurement region and each one of the fourth signals is representative of an amount of the second radiation received from the measurement region at a respective one of the second plurality of times; and

calculating, by the at least one processor, a capillary refill time based on a second trend of the second ratios or a value of one of the second ratios.

41. The method of claim 37, further comprising:

identifying, by the at least one processor, at least one derivative value of the second trend; and

identifying, by the at least one processor, a capillary refill time based on the at least one derivative value.

31-32. -32. (canceled)

35-36. -36. (canceled)

38-40. -40. (canceled)

42. (canceled)