Pulse Oximeter Venous Pulsation Detection via Phase Difference
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Solution Overview
Problem
Pulse oximeters face inaccuracies due to venous pulsation artifacts, which can cause incorrect oxygen saturation and pulse rate measurements by mixing venous and arterial blood signals, and are challenging to detect effectively.
Innovation Solution
A pulse oximeter system that detects venous pulsation by measuring the phase difference between infrared and red light signals, using Lissajous plots to determine the openness of the ellipse formed by these signals, and comparing this measure to a threshold to identify the presence of venous pulsation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pulse oximetry is used to measure blood oxygen saturation, then oxygen saturation and pulse rate can be obtained, but venous pulsation artifacts cause inaccurate measurements by mixing venous and arterial blood signals
Solution Approach 1:
The invention segments the blood signal into arterial and venous components by analyzing phase differences between infrared and red light signals. The arterial pulse and venous pulse are separated through phase comparison, allowing the system to identify and exclude venous pulsation artifacts from the measurement, thereby improving both accuracy and reliability.
Solution Approach 2:
The invention introduces phase difference analysis as an intermediary mechanism to detect venous pulsation. By using the phase relationship between infrared and red light signals as a mediator, the system can identify the presence of venous pulsation and distinguish it from arterial signals, preventing inaccurate measurements.
2Measurement precision
If venous pulsation detection is added to the pulse oximetry system, then venous pulsation can be detected and accuracy improved, but device complexity increases
Solution Approach 1:
The invention makes the existing pulse oximetry system multi-functional by enabling it to perform both traditional oxygen saturation measurement and venous pulsation detection using the same infrared and red light signals. The phase difference analysis is integrated into the existing signal processing pipeline, allowing the system to achieve multiple functions without adding separate detection hardware.
Solution Approach 2:
The invention changes the analysis parameter from simple amplitude comparison to phase difference analysis. By examining the phase relationship between infrared and red light signals, the system can detect venous pulsation without requiring additional sensors or complex hardware modifications, thus managing complexity while improving detection capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively detects venous pulsation, enabling clinicians to address the issue and improve the accuracy of oxygen saturation and pulse rate measurements by distinguishing between arterial and venous blood signals, thereby reducing incorrect readings.
Implementation Method 1
photo-electrically senses the absorption and scattering of light in such tissue
Implementation Method 2
obtaining a measure of a phase difference between the first and second electromagnetic radiation signals
Data Source
AI summary
A method and device for detecting the presence of mixed venous and arterial blood pulsation in tissue, including receiving first and second electromagnetic radiation signals from a blood perfused tissue portion corresponding to infrared and red wavelengths of light, obtaining a measure of a phase difference between the first and second electromagnetic radiation signals, comparing the measure with a threshold value to form a comparison, and detecting the presence or absence of venous pulsation using the comparison.