SYSTEM AND METHOD FOR CHARACTERIZING CIRCULATORY BLOOD FLOW

• US 20130267858A1
• Filed: 03/15/2013
• Published: 10/10/2013
• Est. Priority Date: 07/08/2010
• Status: Active Grant

• Current Assignee: Intelomed, Inc.
• Original Assignee: Intelomed, Inc.
• Inventors: Berkow, Jan K., Brumfield, Anne M.
• Granted Patent: US 9,002,440 B2
• Time in Patent Office: Days
• US Class Current: 600/479
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• 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 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes 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 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• 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

Abstract

A computer-implemented method for characterizing circulatory blood volume and autoregulatory compensatory mechanisms to maintain circulatory blood volume is disclosed. A biological signal that emulates the arterial pulse wave is collected from a sensor. Three derived parameters are extrapolated from the biological signal. The first parameter, circulatory stress, reflects of the changes of the heart rate frequency. The second, circulatory blood volume, reflects the changes in the frequency strength of the heart rate frequency. The third, Pulse Volume Alteration (PVA) Index is a ratio of the sum of the strengths of the heart rate frequency harmonics to the strength of the heart rate frequency of the unprocessed biological signal. Each parameter is compared to a threshold value and assessed to determine an adequacy of circulatory blood volume and an appropriateness of the autoregulatory mechanisms used to maintain circulatory blood volume adequacy.

Claims

1. A computer-implemented method, 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, wherein calculating comprises calculating a PVA Index.

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 calculating a derived parameter further comprises calculating one of circulatory blood volume and 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, further comprising the step of storing said derived parameter in a memory.

8. The method as in claim 1, further comprising the step of assessing, using said processor, an adequacy of a circulatory blood volume or an adequacy of at least one compensatory mechanism.

9. The method as in claim 1, further comprising the step of generating, using said processor, an output.

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

11. 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 comprising a PVA Index.

12. The system as in claim 11, further comprising said sensor.

13. The system as in claim 11, further comprising a module configured to condition said signal.

14. The system as in claim 11, further comprising a memory for storing said derived parameter.

15. The system as in claim 11, wherein said derived parameter comprises at least one of circulatory stress and circulatory blood volume.

16. 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 comprising at least one of a PVA Index.

17. The computer-implemented apparatus as in claim 16, 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.

18. A non-transitory 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 comprising a PVA Index; and

f. compare said derived parameter to a threshold value.