NONINVASIVE DETERMINATION OF INTRAVASCULAR AND EXCTRAVASCULAR HYDRATION USING NEAR INFRARED SPECTROSCOPY

• US 20140171759A1
• Filed: 01/27/2014
• Published: 06/19/2014
• Est. Priority Date: 02/15/2012
• Status: Abandoned Application

• Current Assignee: LVD Innovation I, Inc.
• Original Assignee: Benjamin Ver Steeg, Craig William White
• Inventors: White, Craig William, Ridder, Trent Daniel, Ver Steeg, Benjamin, Laaksonen, Bentley, Treese, Derek F., Price, Glenn Leo
• Application Number:
  US14/164,782
• Publication Number:
  US 20140171759A1
• Time in Patent Office: Days
• US Class Current: 600/306
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/117 Identification of persons methods or arrangements for recognising patterns, e.g. fingerprints, G06F18/00, G06V40/00; identification of persons by analysing their voice or speech G10L17/00
• CPC Class Codes: A61B 5/443 Evaluating skin constituents, e.g. elastin, melanin, water
• CPC Class Codes: A61B 5/4869 Determining body composition
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6835 Supports or holders, e.g., articulated arms
• CPC Class Codes: A61B 5/70 Means for positioning the patient in relation to the detecting, measuring or recording means
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7257 using Fourier transforms

Abstract

An apparatus and method for non-invasive determination of hydration, hydration state, total body water, or water concentration by quantitative spectroscopy. The system includes subsystems optimized to contend with the complexities of the tissue spectroscopy, high signal-to-noise ratio and photometric accuracy requirements, tissue sampling errors, calibration maintenance, and calibration transfer. The subsystems include an illumination subsystem, a tissue sampling subsystem, a spectrometer subsystem, a data acquisition subsystem, a computing subsystem, and a calibration subsystem.

Claims

1. A system to determine a hydration state of a subject, comprising:

(a) a spectroscopic system configured to determine a spectroscopic signal representative of the response of the subject'"'"'s tissue to incident light;

(b) an analysis system configured to determine intravascular hydration, extravascular hydration, or both, from the spectroscopic signal.

2. A system as in claim 1, wherein the spectroscopic system is configured to determine a spectroscopic signal at a plurality of times spanning at least one heartbeat of the subject, and wherein the analysis system is configured to determine intravascular hydration from one or more components of the spectroscopic signal that varies with the heartbeat of the subject.

3. A system as in claim 2, wherein the spectroscopic system is configured to determine a spectroscopic signal at a plurality of times spanning at least two heartbeats of the subject.

4. A system as in claim 2, wherein the analysis system is configured to determine a frequency corresponding to the heart rate of the subject, and to determine intravascular hydration from components of the spectroscopic signal that vary at the determined frequency.

5. A system as in claim 2, wherein the analysis system is configured to determine extravascular hydration from one or more components of the spectroscopic signal that does not vary with the heartbeat of the subject.

6. A system as in claim 2, wherein the analysis system is configured to determine a frequency corresponding to the heart rate of the subject, and to determine extravascular hydration from the spectroscopic signal after filtering out the determined frequency from the spectroscopic.

7. A system as in claim 1, wherein the analysis system is configured to determine intravascular hydration from the spectroscopic signal according to a first method, and to determine extravascular hydration from the spectroscopic signal according to a second method, wherein the first method is distinct from the second method.

8. A system as in claim 1, wherein the spectroscopic system is configured to determine a plurality of spectroscopic signals representative of the response of the subject'"'"'s tissue to incident light at a plurality of distinct times, and wherein the analysis system is further configured to determine a time-dependent change in intravascular hydration, extravascular hydration, or both, responsive to the plurality of spectroscopic signals.

9. A system as in claim 1, wherein the analysis system is configured to distinguish hydration from hypervolemia or hypovolemia.

10. A system as in claim 1, wherein the analysis system is further configured to determine an analyte property, other than hydration, from the spectroscopic signal.

11. A system as in claim 1, wherein the analysis system is configured to determine hydration from a model relating spectroscopic signals to hydration.

12. A system as in claim 1, further comprising a hematocrit sensor, and wherein the analysis system is configured hydration from the spectroscopic signal and from the hematocrit sensor output.

13. A system as in claim 1, wherein the incident light is near-infrared light.

19. A system as in claim 1, wherein the analysis system is configured to determination intravascular hydration from the spectroscopic signal.

20. A system as in claim 1, wherein the analysis system is configured to determination extravascular hydration from the spectroscopic signal.

14. A method of determining hydration of a subject, comprising:

(a) determining a signal representative of the response of the subject'"'"'s tissue to incident light at a plurality of wavelengths;

(b) determining intravascular hydration and extravascular hydration from the signal.

15. A method as in claim 14, wherein step (a) comprises determining the response of the subject'"'"'s tissue to near-infrared light at a plurality of distinct times.

16. A method as in claim 15, wherein the plurality of distinct times span one or more heartbeats of the subject.

17. A method as in claim 16, wherein step (b) comprises determining a frequency corresponding to the heart rate of the subject, and determining intravascular hydration from components of the spectroscopic signal that vary at the determined frequency.

18. A method as in claim 16, wherein step (b) comprises determining a frequency corresponding to the heart rate of the subject, and determining extravascular hydration from components of the spectroscopic signal that do not vary at the determined frequency.