SYSTEM AND METHOD FOR CHARACTERIZING CIRCULATORY BLOOD FLOW

• US 20120029374A1
• Filed: 07/08/2011
• Published: 02/02/2012
• Est. Priority Date: 07/08/2010
• Status: Active Grant

• Current Assignee: Intelomed, Inc.
• Original Assignee: Intelomed, Inc.
• Inventors: Berkow, Jan
• Granted Patent: US 9,173,579 B2
• Time in Patent Office: Days
• US Class Current: 600/526
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/0261 Strain gauges
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/4884 inducing physiological or psychological stress, e.g. applications for stress testing
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00

Abstract

A computer-implemented method for characterizing circulatory blood volume is disclosed. The method has the steps of acquiring a biological signal that emulates the arterial pulse wave from a sensor. Two derived parameters, circulatory stress, which reflects a harmonic of heart rate, and circulatory blood flow, which reflects the amplitude of the unprocessed biological signal, are extrapolated from the biological signal, and are each compared to a threshold value and assessed to determine an adequacy of circulatory blood volume. In embodiments, the assessment of circulatory blood volume is used to manage a patient'"'"'s cardiovascular autoregulatory function or the adequacy of transfer of fluids to and from the circulatory system, with the ultimate goal of achieving a circulatory blood volume that adequately supplies the demands of the patient'"'"'s tissues and organs.

Claims

1. A computer-implemented method for characterizing circulatory blood volume, comprising the steps of:

a. acquiring, using a processor, a biological signal from a sensor;

b. conditioning, using said processor, said signal to create a conditioned signal;

c. processing, using said processor, said conditioned signal; and

d. calculating, using said processor, a derived parameter.

2. The method as in claim 1, further comprising the step of comparing, using said processor, said derived parameter to a threshold value.

3. The method as in claim 1, wherein said biological signal is a photo-optic signal.

4. The method as in claim 1, wherein said sensor is a photo-optic device.

5. The method as in claim 1, wherein said derived parameter is one of circulatory blood flow or circulatory stress.

6. The method as in claim 1, wherein said step of conditioning comprises at least one of the following the steps of:

a. amplifying, using said processor, said biological signal;

b. converting, using said processor, said biological signal to an analog waveform; and

c. inverting, using said processor, said biological signal.

7. The method as in claim 1, wherein said step of processing comprises at least one of the following steps of:

a. separating, using said processor, said conditioned signal into contiguous time windows;

b. decomposing, using said processor, said conditioned signal into a fundamental band and at least one harmonic band;

c. filtering, using said processor, at least one of said bands; and

d. identifying, using said processor, a baseline.

8. The method as in claim 1, further comprising the step of storing said derived parameter in a memory.

9. The method as in claim 1, further comprising the step of assessing, using said processor, an adequacy of said circulatory blood volume.

10. The method as in claim 1, further comprising the step^{-of generating, using said processor, an output.}

11. The method as in claim 1, wherein at least one of said steps uses a second processor.

12. A system for characterizing circulatory blood volume, comprising a processor that includes a module configured to process a biological signal acquired from a sensor to calculate a derived parameter.

13. The system as in claim 12, further comprising said sensor.

14. The system as in claim 12, further comprising a module configured to condition said signal.

15. The system as in claim 12, further comprising a memory for storing said derived parameter.

16. The system as in claim 12, wherein said derived parameter is at least one of circulatory stress or circulatory blood flow.

17. A computer-implemented apparatus for characterizing circulatory blood volume, comprising:

a. means for acquiring a biological signal;

b. means for conditioning said signal to create a conditioned signal;

c. means for processing said conditioned signal; and

d. means for calculating a derived parameter.

18. The computer-implemented apparatus as in claim 17, further comprising at least one of:

a. means for amplifying said biological signal;

b. means for converting said biological signal to an analog waveform; and

c. means for inverting said biological signal.

19. The computer-implemented apparatus as in claim 17, further comprising at least one of:

a. means for separating said conditioned signal into contiguous time windows;

b. means for decomposing said conditioned signal into a fundamental band and at least one harmonic band;

c. means for filtering at least one of said bands;

d. means for identifying a baseline; and

e. means for assessing an adequacy of circulatory blood flow.

20. A computer-readable medium having stored therein instructions which, when executed by a processor, cause the processor to:

a. acquire a signal related to a cardiovascular pulse wave from a sensor;

b. condition said signal to create a conditioned signal;

c. separate said conditioned signal into contiguous time windows;

d. process said decomposed signal;

e. calculate a derived parameter; and

f. compare said derived parameter to a threshold value.