Tissue Spectral Correction in Red-Infrared Pulse Oximetry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pulse oximeter measurements are prone to errors due to variations in tissue spectral characteristics, such as skin pigmentation, leading to inaccurate SpO2 readings.
Innovation Solution
A pulse oximeter system that includes emitters for two wavelengths of light (red and infrared) to estimate tissue scattering or absorption, calculates correction factors based on detected signal ratios, and applies these factors to correct SpO2 measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse oximetry uses standard light wavelengths to measure SpO2, then the measurement process is simple and fast, but measurement precision deteriorates due to errors from tissue spectral characteristics like skin pigmentation
Solution Approach 1:
The patent segments the correction process into multiple components: measuring multiple wavelengths (red and infrared), calculating separate correction factors for each wavelength based on tissue spectral characteristics, and applying these corrections to the SpO2 measurement. This segmentation allows the system to address the complexity of tissue spectral variations through systematic, manageable steps without overwhelming the device architecture.
Solution Approach 2:
The patent changes the measurement parameters by introducing additional wavelength measurements beyond the standard single-wavelength approach. By measuring at multiple wavelengths (e.g., red and infrared) and using these to calculate correction factors, the system adjusts the measurement parameters to compensate for tissue spectral characteristics, thereby improving SpO2 accuracy without fundamentally redesigning the core oximetry function.
2Measurement precision
If the pulse oximeter measures multiple wavelengths to correct for tissue spectral characteristics, then measurement precision improves, but the number of measurements and processing steps increases
Solution Approach 1:
The patent applies preliminary action by measuring multiple wavelengths and calculating correction factors before the final SpO2 determination. The system performs these preliminary measurements and corrections in advance, allowing the main SpO2 calculation to benefit from pre-computed correction values. This preliminary processing of tissue spectral characteristics enables faster final measurements while maintaining high precision.
Solution Approach 2:
The patent implements feedback by using the measured tissue spectral characteristics (from multiple wavelengths) to generate correction factors that feed back into the SpO2 calculation. The system continuously monitors tissue properties and adjusts the SpO2 measurement based on this feedback, creating a closed-loop process that maintains measurement precision while optimizing speed through iterative refinement.
3Measurement precision
If correction factors are applied to account for skin pigmentation and tissue characteristics, then measurement precision improves, but device complexity and computational requirements increase
Solution Approach 1:
The patent introduces correction factors as intermediary elements that mediate between the raw multi-wavelength measurements and the final SpO2 value. These correction factors serve as intermediaries that encapsulate the complexity of tissue spectral characteristics, allowing the system to handle complex biological variations through standardized correction parameters rather than complex real-time calculations during the main measurement process.
Solution Approach 2:
The patent performs the complex calculation of correction factors in advance based on preliminary wavelength measurements. By pre-calculating these correction values from the multi-wavelength data, the system reduces the computational burden during the main SpO2 measurement process. This preliminary computation of correction factors simplifies the real-time processing requirements while maintaining high measurement 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
Improves the accuracy of SpO2 measurements by accounting for tissue spectral characteristics, particularly skin pigmentation, through the use of correction factors derived from signal ratios and normalization techniques.
Implementation Method 1
two optical sources, typically light-emitting-diodes (LEDs), may be used to inject light into the tissue
Implementation Method 2
A photodiode is used to capture the light after propagating through blood perfused tissue
Implementation Method 3
the spectrum of skin pigmentations can result in LED light for a pulse oximeter being scattered and absorbed differently
Implementation Method 4
skin pigmentation (or other characteristics of tissue causing light scattering or absorption (spectral characteristics of tissue)
Data Source
AI summary
The present disclosure provides systems and methods for correcting for errors dependent upon spectral characteristics of tissue for a medical device by estimating a spectral characteristic of tissue providing error due to scattering or absorption of emitted light based upon a ratio of measurements for a patient.