VENOUS OXYGEN SATURATION SYSTEMS AND METHODS
First Claim
1. A method for determining a subject'"'"'s physiological condition, comprising:
- obtaining a first photoplethysmographic signal from the subject, based on light transmission at a first wavelength, and removing a pulsatile component from the first signal to create a first filtered signal indicative of a first baseline modulation;
obtaining a second photoplethysmographic signal from the subject, based on light transmission at a second wavelength, and removing a pulsatile component from the second signal to create a second filtered signal indicative of a second baseline modulation;
determining a first ratio that includes an amplitude of the first filtered signal divided by a first numeric component;
determining a second ratio that includes an amplitude of the second filtered signal divided by a second numeric component; and
dividing the first ratio by the second ratio to create a ratio of ratios indicative of the subject'"'"'s physiological condition.
1 Assignment
0 Petitions
Accused Products
Abstract
Methods and systems are discussed for determining venous oxygen saturation by calculating a ratio of ratios from respiration-induced baseline modulations. A calculated venous ratio of ratios may be compared with a look-up table value to estimate venous oxygen saturation. A calculated venous ratio of ratios is compared with an arterial ratio of ratios to determine whether baseline modulations are the result of a subject'"'"'s respiration or movement. Such a determination is also made by deriving a venous ratio of ratios using a transform technique, such as a continuous wavelet transform. Derived venous and arterial saturation values are used to non-invasively determine a cardiac output of the subject.
-
Citations
28 Claims
-
1. A method for determining a subject'"'"'s physiological condition, comprising:
-
obtaining a first photoplethysmographic signal from the subject, based on light transmission at a first wavelength, and removing a pulsatile component from the first signal to create a first filtered signal indicative of a first baseline modulation; obtaining a second photoplethysmographic signal from the subject, based on light transmission at a second wavelength, and removing a pulsatile component from the second signal to create a second filtered signal indicative of a second baseline modulation; determining a first ratio that includes an amplitude of the first filtered signal divided by a first numeric component; determining a second ratio that includes an amplitude of the second filtered signal divided by a second numeric component; and dividing the first ratio by the second ratio to create a ratio of ratios indicative of the subject'"'"'s physiological condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A system for deriving information pertaining to physiological information, the system comprising:
-
a red light source and an infrared light source, each configured to direct light onto the subject; a detector that detects light from the light sources to provide a pulse oximetry signal having pulsatile components indicative of light transmission by arterial blood in the subject, and baseline components indicative of light transmission by venous blood in the subject; a filter that removes a subset of the pulsatile components from the pulse oximetry signal to create a filtered signal; a signal processor programmed to; (a) identify within the filtered signal a first amplitude indicative of a baseline component from the red light source and a second amplitude indicative of a baseline component from the infrared light source; (b) determine a first ratio, comprising the first amplitude divided by a mean of a plurality of amplitudes from the red light source; (c) determine a second ratio, comprising the second amplitude divided by a mean of a plurality of amplitudes from the infrared light source; and (d) divide the first and second ratios to create a modified signal, indicative of oxygen concentration in venous blood. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
-
Specification