Photoplethysmography device and method

• US 8,868,149 B2
• Filed: 10/16/2012
• Issued: 10/21/2014
• Est. Priority Date: 07/30/2009
• Status: Active Grant

• Current Assignee: Oxitone Medical Ltd.
• Original Assignee: Oxitone Medical Ltd.
• Inventors: Eisen, Leon, Kamisnky, Alexander, Fine, Ilya
• Primary Examiner(s): Laballe, Clayton E
• Assistant Examiner(s): Smith, Linda B
• Application Number:
  US13/653,233
• Publication Number:
  US 20130131475A1
• Time in Patent Office: 735 Days
• Field of Search: 600/324
• US Class Current: 600/324
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• 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 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• 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 skin of the subject 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),

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 lower data quality value.