System and method for characterizing circulatory blood flow

• US 10,512,408 B2
• Filed: 08/19/2015
• Issued: 12/24/2019
• Est. Priority Date: 07/08/2010
• Status: Active Grant

• Current Assignee: Intelomed, Inc.
• Original Assignee: Intelomed, Inc.
• Inventors: Berkow, Jan
• Primary Examiner(s): Jang, Christian
• Assistant Examiner(s): Alter, Mitchell E
• Application Number:
  US14/830,344
• Publication Number:
  US 20160066799A1
• Time in Patent Office: 1,588 Days
• Field of Search: 600526
• 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 method for characterizing a circulatory blood flow of a human body, the method comprising:

receiving, by a computing device, a time domain biological signal emulating an arterial pulse wave from a sensor associated with the human body of a patient;

performing frequency analysis of the time domain biological signal to determine at least one of a fundamental frequency and an integer harmonic of a heart rate from the time domain biological signal wherein each of the fundamental frequency and integer harmonic is characterized by a frequency amplitude;

calculating, by the computing device, at least one normalized parameter including calculating a percent difference of at least one of the frequency amplitudes of the at least one of a fundamental frequency and an integer harmonic from the at least one pre-determined parameter baseline;

comparing, by the computing device, the at least one normalized parameter to a predetermined threshold value;

characterizing the circulatory blood flow from the comparison of the at least one normalized parameter to the predetermined threshold value; and

providing an indication reflective of the circulatory blood flow and the changes in circulatory blood volume over contiguous time intervals to a person monitoring the patient'"'"'s human body for the management of the cardiovascular function of the patient.

2. The method of claim 1, further comprising calculating, by the computing device, the at least one pre-determined parameter baseline from a variance from a filtered and conditioned time domain biological signal.

3. The method of claim 2, further comprising dividing, by the computing device, the filtered and conditioned time domain biological signal into a plurality of discrete time windows.

4. The method of claim 2, wherein the filtered and conditioned time domain biological signal comprises an amplified signal or an inverted signal.

5. The method of claim 1, further comprising applying, by the computing device, a continuous-time filter to at least a portion of the time domain biological signal.

6. The method of claim 5, wherein the continuous-time filter comprises one or more of the following:

a Butterworth filter;

a Chebyshev filter;

a Bessel filter;

an elliptical filter;

a custom low pass filter; and

a filter based on determining a moving average.

7. The method of claim 1, wherein the sensor comprises one or more of the following:

a transmissive photo-optic sensor;

a reflective photo-optic sensor;

a pressure transducer;

a tonometry device;

a strain gauge;

an ultrasound device;

an electrical impedance device; and

a radar device.

8. The method of claim 1, wherein the predetermined threshold value is a clinically validated value from a specific patient population.

9. The method of claim 1, wherein the predetermined threshold value is associated with a pre-symptomatic circulatory blood volume inadequacy condition.

10. The method of claim 1, wherein the predetermined threshold value is associated with a symptomatic circulatory blood volume inadequacy condition.