PHOTOPLETHYSMOGRAPHY DEVICE AND METHOD

• US 20110082355A1
• Filed: 07/30/2010
• Published: 04/07/2011
• Est. Priority Date: 07/30/2009
• Status: Abandoned Application

• Current Assignee: Oxitone Medical Ltd.
• Original Assignee: Oxitone Medical Ltd.
• Inventors: Kamisnky, Alexander, Eisen, Leon, Fine, Ilya
• Application Number:
  US12/847,048
• Publication Number:
  US 20110082355A1
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence

Abstract

A system and method for measuring one or more light-absorption related blood analyte concentration parameters of a mammalian subject, is disclosed. In some embodiments, the system comprises: a) a photoplethysmography (PPG) device configured to effect a PPG measurement by illuminating skin of the subject with at least two distinct wavelengths of light and determining relative absorbance at each of the wavelengths; b) a dynamic light scattering measurement (DLS) device configured to effect a DLS measurement of the subject to rheologically measure a pulse parameter of the subject; and c) electronic circuitry configured to: i) temporally correlating the results of the PPG and DLS measurements; and ii) accordance with the temporal correlation between the PPG and DLS measurements, assessing value(s) of the one or more light-absorption related blood analyte concentration parameter(s).

Claims

1. ) A method of measuring one or more light-absorption related blood analyte concentration parameters of a mammalian subject, the method comprising:

a) effecting a photoplethysmography (PPG) measurement of the subject by illuminating the patient with at least two distinct wavelengths of light and determining relative absorbance at each of the wavelengths;

b) effecting a dynamic light scattering measurement (DLS) of the subject to rheologically measure a pulse parameter of the subject;

c) temporally correlating the results of the PPG and DLS measurements; and

d) in accordance with the temporal correlation between the PPG and DLS measurements, assessing value(s) of the one or more light-absorption related blood analyte concentration parameter(s).

2. ) The method of claim 1 wherein the blood analyte concentration parameter is selected from the group consisting of a blood oxyhemoglobinn concentration parameter, a blood carboxyhemoglobin concentration parameter and an arteriovenous oxygen difference (AV difference) parameter.

3. ) The method of claim 1 wherein temporal correlating and/or value assessing includes:

i) determining from the measurement of step (b) a description of a pulse timing; and

ii) in accordance with the DLS pulse-timing determining, associating each PPG measurement of a plurality of measurements with a different respective pulse-relative time value describing a pulse-relative temporal position of the PPG measurement within the pulse; and

iii) determining the light-absorption related blood analyte concentration parameter in accordance with pulse-relative temporal positions.

4. ) The method of claim 2 wherein the pulse-relative temporal position describes at least one of:

i) a time elapsed between the occurrence of a pulse event and the subsequent measurement time of PPG data; and

ii) a time elapsed between the measurement time of PPG data and an occurrence of a subsequent pulse event.

5. ) The method of claim 4 wherein the pulse event is selected from the group consisting of an initiation of the systolic phase, a peak of the systolic phase, an initiation of the diastolic phase, and a zero-crossing of a time derivative of a pulse value.

6. ) The method of claim 1 wherein the DLS is single scattering DLS and/or single wavelength DLS.

7. ) The method of claim 1 wherein the DLS measurement and the PPG measurements are local to each other.

8. ) The method of claim 1 wherein step (d) includes:

i) computing a parameter descriptive of the temporal correlation between measurements of step (b) and step (c); and

ii) in accordance with the computed temporal correlation parameter, determining a time-dependent PPG data quality value associated with each PPG measurement; and

iii) computing the light-absorption related blood analyte concentration parameter(s) by assigning greater weight to PPG data having a higher data quality value and lesser or no weight to PPG data having a higher data quality value.

9. ) A method of measuring one or more light-absorption related blood analyte concentration parameters of a mammalian subject, the method comprising:

a) effecting a photoplethysmography (PPG) measurement of the subject by illuminating the patient with at least two distinct wavelengths of light and determining relative absorbance at each of the wavelengths;

b) effecting a non-PPG rheological pulse measurement to rheologically measure a pulse parameter of the subject;

c) temporally correlating the results of the PPG and rheological measurements; and

d) in accordance with the temporal correlation between the PPG and rheological pulse measurements, assessing value(s) of the one or more light-absorption related blood analyte concentration parameter(s).

10. ) The method of claim 9 wherein the effecting of the non-PPG rheological pulse measurement includes effecting at least one of:

a) a speckle analysis;

b) a measurement of a blood shear stress;

c) a light interference measurement;

d) a acoustic or optical Doppler measurement; and

e) an electrical impedance measurement.

11. ) The method of claim 9 wherein the blood analyte concentration parameter is selected from the group consisting of a blood oxyhemoglobinn concentration parameter, a blood carboxyhemoglobin concentration parameter and an arteriovenous oxygen difference (AV difference) parameter.

12. ) (canceled)

13. ) (canceled)

14. ) A system for measuring one or more light-absorption related blood analyte concentration parameters of a mammalian subject, the method comprising:

a) a photoplethysmography (PPG) device configured to effect a PPG measurement by illuminating the patient with at least two distinct wavelengths of light and determining relative absorbance at each of the wavelengths;

b) a dynamic light scattering measurement (DLS) device configured to effect a DLS measurement of the subject to rheologically measure a pulse parameter of the subject; and

c) electronic circuitry configured to;

i) temporally correlating the results of the PPG and DLS measurements; and

ii) accordance with the temporal correlation between the PPG and DLS measurements, assessing value(s) of the one or more light-absorption related blood analyte concentration parameter(s).