Optical Blood Measurement Pathlength Scaling
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Solution Overview
Problem
Conventional optical-based blood measurement devices face inaccuracies due to patient-specific noise and inconsistencies, such as tissue pigment variations, vascular inhomogeneity, and incorrect application, leading to errors in determining physiological parameters like hemoglobin concentration and oxygen saturation.
Innovation Solution
The system emits optical signals with different carrier wavelengths, detects and processes their propagation pathlengths and intensities to scale the measurements, compensating for variations and improving accuracy by employing ratiometric relationships and photon density wave techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical-based blood measurement devices are used, then the measurement process is simple and non-invasive, but the accuracy is limited due to patient-specific noise and tissue variations
Solution Approach 1:
The patent introduces pathlength as an intermediary parameter that mediates between the raw optical signal and the final physiological parameter calculation. By measuring the propagation pathlength of optical signals through tissue and using it to scale the detected intensities, the system compensates for tissue-specific variations without requiring complex hardware modifications. This intermediary approach resolves the contradiction by adding a computational layer that improves accuracy while maintaining relative system simplicity.
Solution Approach 2:
The patent changes the parameter being measured from simple optical intensity to a scaled intensity that accounts for propagation pathlength. By identifying and processing the pathlength parameter alongside the detected intensity, the system transforms the measurement process to compensate for tissue variations. This parameter change enables more accurate physiological parameter determination while keeping the device architecture relatively straightforward.
2Reliability
If optical signals are emitted through tissue to measure physiological parameters, then non-invasive measurement is achieved, but optical shunting through air gaps or blood-deficient tissue causes measurement errors
Solution Approach 1:
The patent implements feedback by using the measured propagation pathlength to adjust and scale the detected optical intensities. The system measures the actual pathlength traveled by optical signals through tissue and feeds this information back into the calculation process to compensate for shunting effects. This feedback mechanism improves reliability by dynamically adjusting measurements based on the actual optical propagation conditions experienced in each patient-specific scenario.
3Measurement precision
If multiple optical signals with different carrier wavelengths are emitted, then pathlength variations can be accounted for, but the device complexity and processing requirements increase
Solution Approach 1:
The patent applies multi-functionality by using multiple optical signals with different carrier wavelengths to serve multiple purposes simultaneously. The different wavelengths provide information about both the physiological parameters of interest and the propagation pathlength through tissue. This universal approach allows the system to extract multiple pieces of useful information from a single measurement setup, improving accuracy while avoiding the need for separate measurement systems for each parameter.
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 of physiological parameter determination by accounting for pathlength variations, reducing errors and inconsistencies, and providing reliable measurements of parameters like hemoglobin concentration, oxygen saturation, and heart rate.
Implementation Method 1
emitting at least two optical signals for propagation through tissue of the patient, detecting the optical signals after propagation
Implementation Method 2
processing at least the propagation pathlengths to scale the detected intensities for determination of a value of the physiological parameter
Implementation Method 3
employing ratiometric relationships and photon density wave techniques
Data Source
AI summary
Systems and methods for measuring a physiological parameter of tissue in a patient are provided herein. In a first example, a method of measuring a physiological parameter of blood in a patient is provided. The method includes emitting at least two optical signals for propagation through tissue of the patient, detecting the optical signals after propagation, identifying propagation pathlengths of the optical signals, and identifying detected intensities of the optical signals. The method also includes processing at least the propagation pathlengths to scale the detected intensities for determination of a value of the physiological parameter.