Processing of photoplethysmography signals
Inventors
MELKER RICHARD J, null • Malker, Richard J. • Euliano, Neil R. • Stahl, JR., Michael W.
Assignees
CONVERGENT ENGINEERING Inc • University of Florida Research Foundation Inc • Convergent Engr Inc
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-8529459-B2
Publication Date
2013-09-10
Expiration Date
Abstract
Disclosed herein are methods and devices of processing photoplethysmography signal information. The methods for processing will allow numerous medical observations and diagnoses from a simple, non-invasive probe.
Core Innovation
The invention relates to processing a raw plethysmography signal stream to separately obtain an AC component signal stream and a DC component signal stream. The method identifies peaks and troughs or extrema of the raw plethysmography signal stream that exist at an expected heart rate, and identifies minimum values, midpoints, or a common point relative to the extrema. The method interpolates between the reference points to define the DC component signal stream or low frequency content, and extracts the interpolated signal from the raw plethysmography signal stream to isolate the AC component signal stream, the DC component signal stream, or a high frequency component signal stream and low frequency content individually.
In another form, the common point is selected relative to the extrema and can be defined using features such as a dicrotic notch, a zero crossing point, an inflection point, or a maximum point. The invention also includes separating low-frequency content from a raw plethysmography signal stream by interpolating between common points to represent low frequency content and extracting the interpolated low frequency content from the raw plethysmography signal stream. Further, the high frequency component signal stream and low frequency content are defined to represent different physiological components, and multiple low-frequency components can be separated.
Claims Coverage
The independent claims cover five main claim scopes for isolating physiological signal components from a raw plethysmography signal stream, including AC/DC separation and high-frequency versus low-frequency separation, as well as corresponding system and computer program product implementations. Across the independent claims, the inventive approach repeatedly uses expected-heart-rate extrema, peaks, and troughs with interpolation between defined reference points to extract a DC or low-frequency component while separately obtaining the remaining component(s).
Expected-heart-rate peak/trough interpolation to extract DC while isolating AC
A method of isolating an AC component signal stream and a DC component signal stream from a raw plethysmography signal stream by identifying peaks and troughs that exist at an expected heart rate; identifying minimum values or midpoints between the peaks and troughs; interpolating between the midpoints or minimum values to define the DC component signal stream; and extracting the interpolated DC component signal stream from the raw plethysmography signal stream to separately obtain the AC component signal stream, whereby the AC component signal stream and the DC component signal stream are individually isolated.
Expected-heart-rate peak/trough interpolation DC extraction in a patient processing system
A system for processing plethysmography signals from a patient comprising a pulse oximeter probe configured to generate a raw plethysmography signal stream and a computer with a first program module causing the computer to process the raw plethysmography signal stream to obtain AC component signal stream or DC component signal stream, or both, by identifying peaks and troughs that exist at an expected heart rate; identifying minimum values or midpoints between the peaks and troughs; interpolating between the midpoints or minimum values to define the DC component signal stream; and extracting the interpolated DC component signal stream from the raw plethysmography signal stream, thereby separately obtaining the AC component signal stream, whereby the AC component signal stream and the DC component signal stream are individually isolated, and a second program module causing the computer to analyze the AC component signal stream or the DC component signal stream, or both, to determine a decrease in amplitude.
Computer program product with expected-heart-rate peak/trough interpolation DC extraction
A computer program product comprising non-transitory computer-usable medium with a first program code module configured to cause a computer to process a raw plethysmography signal stream obtained from a pulse oximeter probe by identifying peaks and troughs that exist at an expected heart rate; identifying minimum values or midpoints between the peaks and troughs; interpolating between the midpoints or minimum values to define the DC component signal stream; and extracting the interpolated DC component signal stream from the raw plethysmography signal stream, thereby separately obtaining an AC component signal stream, whereby the AC component signal stream and the DC component signal stream are individually isolated; and a second program code module configured to cause the computer to analyze the AC component signal stream or the DC component signal stream, or both, to determine a decrease in amplitude of either component, or both.
Expected-heart-rate extrema with common-point interpolation for DC extraction
A method of isolating an AC and DC component signal stream from a raw plethysmography signal stream by identifying extrema that exist at an expected heart rate; identifying a common point relative to the extrema; interpolating between the common points to define the DC component signal stream; and extracting the interpolated DC component signal stream from the raw plethysmography signal stream, thereby separately obtaining the AC component signal stream, whereby the AC component signal stream and the DC component signal stream are individually isolated.
Expected-heart-rate extrema with common-point interpolation for high-frequency versus low-frequency separation
A method of isolating from a raw plethysmography signal stream a high frequency component signal stream, a first low frequency component signal stream and a second low frequency component signal stream by identifying extrema that exist at an expected heart rate; identifying a common point relative to the extrema; interpolating between the common points to represent low frequency content of the signal; and extracting the interpolated low frequency content from the raw plethysmography signal stream to separate the high frequency component signal stream from the low frequency content.
Overall, the claim set isolates one component from another by selecting signal features that exist at an expected heart rate, defining reference values or a common point relative to extrema, and interpolating between those reference values to construct and extract a DC or low-frequency content component, leaving AC and/or high-frequency component(s) separately obtained.
Stated Advantages
Improved separation/fidelity of physiological components is stated in the provided patent chunk.
The isolated components enable non-invasive observations including respiratory effort/rate and venous/volume status assessment, as described in the provided patent chunk.
Documented Applications
Non-invasive observation of respiratory effort/rate and venous/volume status assessment using isolated AC/DC or related components, as described in the provided patent chunk.
Illustrative ICU ventilator examples in which AC/DC changes with PEEP are described in the provided patent chunk.
Interested in licensing this patent?