Granted Patent B2

US 12,642,460 · App. 17/922,215 · Granted Jun 2, 2026

Inventors: Mark P. Marriott (Palo Alto, CA); Jeffrey C. Marshall (Belmont, CA); George Stefan Golda (El Granada, CA); Sam Eletr (Paris, FR)

Assignee: RDS

A61B5/14552A61B5/0006A61B5/02416A61B5/352A61B5/366A61B5/6833

Abstract

Claims (27)

1 . A pulse oximetry method comprising:

Placing a photoplethysmography sensor on a body of a patient;

Determining a photoplethysmogram with contribution of venous capillaries lower than 25%;

Determining arterial pulses in the photoplethysmogram; and

Determining peripheral oxygen saturation using a Ratio of Ratios method, wherein the photoplethysmography sensor is placed on a substrate intended to be adhered on a skin of the patient and protrudes from the substrate by a thickness greater than 0.1 mm.

2 . The pulse oximetry method according to claim 1 , wherein

determining the photoplethysmogram with contribution of venous capillaries lower than 25% comprises:

Determining an electrocardiogram in time concordance with the photoplethysmogram;

Detecting a QRS complex of successive heart beats in said electrocardiogram;

Defining a succession of frames of the photoplethysmogram for a time interval between two adjacent heart beats; and

Aggregating two or more of these frames together at each point in time to create a photoplethysmogram for the time interval in which contribution of venous capillaries is lower than 25%.

3 . The pulse oximetry method according to claim 2 , further comprising:

Determining Pulse Transit Time from a time concordant electrocardiogram and photoplethysmogram for each heart beat;

Computing a standard deviation of Pulse Transit Time over a period comprising between 10 and 45 heart beats; and

Determining a confidence level of a peripheral oxygen saturation determination from the standard deviation of Pulse Transit Time.

4 . The pulse oximetry method according to claim 2 , wherein two or more photoplethysmography waveforms of different wavelengths are determined.

5 . The pulse oximetry method according to any one of claim 2 , wherein a constant component and a primary periodic component of said photoplethysmogram are determined.

6 . The pulse oximetry method according to any one of claim 2 , wherein defining the succession of frames includes defining intervals of said photoplethysmogram based on characteristics of said electrocardiogram and averaging values of said photoplethysmogram over a plurality of such intervals.

7 . The pulse oximetry method according to claim 5 , wherein said constant component and said primary periodic component of said photoplethysmogram are determined from said average values.

8 . The pulse oximetry method according to claim 6 , wherein said electrocardiogram includes R wave signals each with a peak value in each of said heart beats and said intervals are determined with respect to the peak values of the R wave signals.

9 . A pulse oximeter comprising a photoplethysmography sensor and an ECG sensor, said pulse oximeter being suitable to implement the pulse oximetry method according to claim 2 .

10 . The pulse oximetry method according to claim 1 , wherein the photoplethysmography sensor comprises an optical lens surrounded by an adhesive layer and wherein the optical lens is protruding, so as to maintain pressure great enough, to compress only the venous capillaries.

11 . The pulse oximetry method according to claim 1 , wherein the photoplethysmography sensor protrudes from the substrate by a thickness greater than 0.5 mm.

12 . The pulse oximetry method according to claim 1 , wherein the photoplethysmography sensor is placed on a back of the patient.

13 . The pulse oximetry method according to claim 12 , wherein the photoplethysmography sensor is placed near a nape region of a neck of the patient.

14 . The pulse oximetry method according to claim 12 , wherein the photoplethysmography sensor is placed on a vertebra.

15 . The pulse oximetry method according to claim 12 , wherein the photoplethysmography sensor is placed on a T1 vertebra.

Assignments (5)

Continuity (4)

References Cited (400)