Blood Flow Monitoring

• US 20120078069A1
• Filed: 07/27/2011
• Published: 03/29/2012
• Est. Priority Date: 06/20/2002
• Status: Abandoned Application

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: MELKER, RICHARD J.
• Application Number:
  US13/191,594
• Publication Number:
  US 20120078069A1
• Time in Patent Office: Days
• US Class Current: 600/340
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 2562/247 Hygienic covers, i.e. for covering the sensor or apparatus during use
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/036 by means introduced into body tracts A61B5/032 and A61B5/035 take precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/0873 using optical means
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/6819 Nose
• CPC Class Codes: A61B 5/682 Mouth, e.g., oral cavity; tongue; Lips; Teeth
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6829 Foot or ankle
• 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 5/7282 : Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61M 16/0003 : Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0051 : with alarm devices
• CPC Class Codes: A61M 16/0057 : Pumps therefor
• CPC Class Codes: A61M 16/021 : operated by electrical means A61M16/202 – A61M16/205 take precedence
• CPC Class Codes: A61M 16/0666 : Nasal cannulas or tubing devices for improving normal breathing through the nose A61F5/08; nose filters A62B23/06; outside holding devices A61M25/02
• CPC Class Codes: A61M 16/0672 : Nasal cannula assemblies for oxygen therapy
• CPC Class Codes: A61M 16/08 : Bellows; Connecting tubes having means for taking samples G01N1/22; Water traps; Patient circuits
• CPC Class Codes: A61M 16/085 : Gas sampling
• CPC Class Codes: A61M 16/20 : Valves specially adapted to medical respiratory devices
• CPC Class Codes: A61M 2202/0007 : introduced into the body
• CPC Class Codes: A61M 2202/0208 : Oxygen
• CPC Class Codes: A61M 2202/03 : Gases in liquid phase, e.g. cryogenic liquids
• CPC Class Codes: A61M 2205/3561 : local, e.g. within room or hospital
• CPC Class Codes: A61M 2205/3569 : sublocal, e.g. between console and disposable
• CPC Class Codes: A61M 2210/0618 : Nose
• CPC Class Codes: A61M 2210/0625 : Mouth
• CPC Class Codes: A61M 2210/0662 : Ears
• CPC Class Codes: A61M 2230/005 : Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/06 : Heartbeat rate only
• CPC Class Codes: A61M 2230/205 : partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/30 : Blood pressure A61M2230/04 takes precedence
• CPC Class Codes: A61M 2230/42 : Rate
• CPC Class Codes: A61M 2230/432 : partial CO2 pressure (P-CO2)

Abstract

The present invention relates to a method of utilizing photoplethysmography obtained from a central site and a non-central site to detect a low blood flow or low blood volume condition. Also disclosed are apparatuses and systems designed to acquire and process physiological information based on photoplethysmograpy signal information from dual sites.

Claims

1. A method of determining hypovolemia in a subject, said method comprising obtaining a first photoplethysmographic (PPG) signal from a central source site of said subject;

obtaining a second PPG signal from a non-central site of said subject; and

monitoring for a difference between said first PPG signal relative to said second PPG signal;

wherein a change between said second PPG signal relative to said first PPG signal indicates a low blood volume condition in the subject.

2. The method of claim 1, wherein said central source site is a nasal alar, nasal septum, cheek or lip of said subject.

3. The method of claim 1, wherein said central source site is a nasal alar of said subject.

4. The method of claim 1, wherein said central source site is a nasal septum of said subject.

5. The method of claim 1, wherein said non-central site is an extremity of said subject.

6. The method of claim 1, wherein said non-central site is a finger or toe of said subject.

7. The method of claim 1, wherein a decrease of said second PPG signal relative to said first PPG signal indicates a low blood flow/low blood volume condition in the subject.

8. A method of determining hypovolemia in a subject, said method comprising

monitoring for a difference between a first PPG signal obtained from a central source site of said subject and a second PPG signal obtained from a non-central site of said subject;

wherein a decrease of said second PPG signal relative to said first PPG signal indicates a low blood flow/low blood volume condition in the subject.

9. The method of claim 8, wherein said central source site is a nasal alar, nasal septum, cheek or lip of said subject.

10. The method of claim 8, wherein said central source site is a nasal alar of said subject.

12. The method of claim 8, wherein said central source site is a nasal septum of said subject.

13. The method of claim 8, wherein said non-central source site is an extremity of said subject.

14. The method of claim 8, wherein said non-central source site is a finger or toe of said subject.

15. An apparatus for analyzing photoplethysmography signals from at least two sites on a living vertebrate, to determine the presence or absence of, or to monitor changes in, impaired peripheral perfusion or volume status comprising:

a. means for receiving pulse oximeter probe signals from at least two sites on a living vertebrate, wherein at least one said site is a central source site and at least one said site is a non-central site; and

means for determining a change in blood volume at at least one non-central site based on the extent to which said at least one non-central site has a lower photoplethysmography signal than said central source site or the photoplethysmograpy signal from one non-central site decreases relative to the signal at the central site over time.

16. The apparatus of claim 15, further comprising a means for presenting results to a user of said apparatus.

17. A monitor system for analyzing photoplethysmography signals from at least two sites on a living vertebrate, to monitor changes in blood flow, comprising:

a. output circuitry to deliver timed signals to energize light generating components of at least two pulse oximeter probes;

b. input circuitry to receive signals from said at least two pulse oximeter probes positioned said at least two sites on a living vertebrate, wherein at least one said site is a central source site and at least one said site is a non-central site;

c. a computer loaded with software to

1. provide timed signals to energize said light generating components;

2. average sufficient signals from each pulse oximeter probe site to obtain a statistically reliable average;

3. calculate a time-set estimate of a photoplethysmography signal based on said statistically reliable average;

4. repeat steps 2 and 3 to obtain sequential time-set estimates of a photoplethysmography signal from each site;

5. compare a sequential time-set estimate of the photoplethysmography signal from the central source site with a sequential time-set estimate, taken at a similar time, of the photoplethysmography signal from the at least one non-central site; and

6. determine a change in blood volume to said at least one non-central site based on the extent to which said non-central site has a lower photoplethsymography signal than said central source site.

18. A monitor system of claim 17, further comprising a read-out device to provide results to a user of said system.

19. The monitor system of claim 17, further comprising software in said computer for estimating blood pressure through analysis of pulse time delay between said at least two sites.

20. A method of observing respiration in a patient, said method comprising monitoring changes in the envelope of a PPG signal from a central source site of said patient.