Respiration Rate Extraction from Raw PPG Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining respiration rate from photoplethysmography (PPG) signals often lack precision due to filtering processes that reduce useful information, making it difficult to accurately measure respiration rate with high confidence.
Innovation Solution
The method involves analyzing raw PPG signals to extract features such as the phase position of the first harmonic of heart beats, which are then resampled to provide a consistent sampling rate, allowing for the determination of respiration rate through Fourier transformation and subsequent analysis using algorithms or neural networks to identify the most probable rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If filtering processes are applied to PPG signals to improve signal quality, then signal stability is improved, but measurement precision deteriorates due to loss of useful information
Solution Approach 1:
The patent extracts the respiration rate information directly from the raw PPG signal without applying filtering operations. By taking out the essential feature (respiration rate) from the raw signal data, the method avoids the information loss that would occur during filtering while still achieving stable and accurate measurements.
2Measurement precision
If raw PPG signals are used to determine respiration rate, then measurement precision is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent segments the PPG signal into distinct features (such as peak detection, slope calculation, and waveform morphology analysis) that can be processed independently. This segmentation allows the complex task of extracting respiration rate from raw signals to be broken down into manageable processing steps, reducing overall system complexity while maintaining high measurement precision.
3Measurement precision
If multiple processing steps are applied to extract respiration rate, then measurement precision is improved, but loss of time increases due to extended processing duration
Solution Approach 1:
The patent performs preliminary actions by pre-defining the key features and parameters to be extracted from the raw PPG signal (such as peak locations, slopes, and waveform characteristics). This preliminary preparation allows the actual respiration rate calculation to be performed more quickly, as the processing steps are already structured and optimized, reducing overall processing time while maintaining high 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 provides a more accurate and confident determination of respiration rate by utilizing the full information in raw PPG signals, improving the precision of respiration rate measurement compared to filtered signals.
Implementation Method 1
PPG is an optical measurement technique that evaluates a time-variant change of light reflectance or transmission of an area or volume of interest. PPG is based on the principle that blood absorbs light more than surrounding tissue
Data Source
AI summary
The present invention relates to a device, system and method for determining a respiration rate of a subject. The device presented comprises an input interface for obtaining a red and/or an infrared photoplethysmography, PPG, signal, a feature signal unit configured to extract a first sequence of features from the PPG signal and to generate a first feature signal from said sequence of features, a resampling unit configured to resample with a resampling function the first feature signal to yield a resampled signal with a constant sampling rate and/or to resample a first derivative to yield a resampled first derivative with a constant sampling rate, a transformation unit configured to calculate a Fourier transform of the resampled signal to yield a transformed resampled signal or to calculate a Fourier transform of the resampled first derivative to yield a transformed resampled first derivative, and an extraction unit configured to extract from the transformed resampled signal a first respiration rate or from the transformed resampled first derivative the first respiration rate, wherein the first sequence of features is a sequence of phases of the first harmonic of a heart beat of the subject with respect to a start of the heart beat and wherein the first feature signal corresponds to the sequence of phases.