Physiological Parameter Sensing Using Correlation-Based Pulse Vector Selection
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Solution Overview
Problem
Existing physiological parameter sensing methods, such as SpO2 monitoring, face challenges in accurately determining blood oxygen saturation, especially in mobile patients or those with severe arrhythmias, due to motion artefacts and respiratory fluctuations, which can lead to erroneous measurements.
Innovation Solution
Incorporating an auxiliary heart rate sensing means into the physiological parameter sensing system to improve the quality assessment of blood volume pulse vectors by determining the strength of correlation between pulse signals and heart rate signals, thereby selecting the most accurate blood volume pulse vector and reducing noise distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional PPG sensing methods are used to measure blood oxygen saturation, then the measurement can be performed continuously and non-invasively, but motion artefacts and respiratory fluctuations cause erroneous measurements and reduce accuracy
Solution Approach 1:
The system derives quality indicator values for multiple blood volume pulse vectors and uses feedback to select the vector with the highest quality indicator, thereby improving measurement reliability by eliminating erroneous measurements caused by motion artifacts and respiratory fluctuations
Solution Approach 2:
The system changes the parameter being measured from raw PPG signals to quality indicator values that reflect the strength of relationship between pulse signals and heart rate signals, allowing selection of the most reliable measurement under varying physiological conditions
2Measurement precision
If multiple blood volume pulse vectors are evaluated to improve SpO2 accuracy, then measurement precision improves, but device complexity and computational requirements increase
Solution Approach 1:
The system uses the physiological signals themselves (heart rate signals and pulse signals) to generate quality indicators that automatically identify the best blood volume pulse vector, eliminating the need for external calibration or complex manual adjustment procedures
Solution Approach 2:
The system replaces complex mechanical or manual signal quality assessment methods with automated computational derivation of quality indicators based on the strength of relationship between physiological signals, simplifying the overall system while improving precision
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
This approach enhances the accuracy and robustness of SpO2 determination by reducing motion artefacts and improving signal quality, leading to more reliable physiological parameter measurements even in challenging conditions.
Implementation Method 1
detection signals derived from detected electromagnetic radiation reflected from, or transmitted through, a skin region
Implementation Method 2
detection signals derived from detected electromagnetic radiation reflected from, or transmitted through, a skin region
Implementation Method 3
blood absorbs light more than surrounding tissue, so variations in blood volume with every heart beat affect transmission or reflectance correspondingly
Implementation Method 4
determining the strength of correlation between pulse signals and heart rate signals
Data Source
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AI summary
The invention provides a physiological parameter sensing system (50) and method in which physiological information indicative of at least one physiological parameter is derived. The approach of the invention is based on constructing multiple pulse signals from different weighted combinations of at least two detection signals, derived from detected electromagnetic radiation directed onto or through a subject's skin region. The weightings are based on different of a set of various blood volume pulse vectors. A quality indication value is derived for each generated pulse signal, where this is based on a derived relationship between an obtained heart rate signal for the patient and the pulse signal. The blood volume pulse vector resulting in the pulse signal having the highest quality indicator value and/or from the derived pulse signal itself is used to derive the physiological parameter information.