Transabdominal Fetal Pulse Oximetry Signal Segmentation
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Solution Overview
Problem
Current fetal monitoring techniques during labor and delivery rely on imperfect measures of fetal heart rate, leading to unnecessary C-sections and complications due to the lack of convenient fetal blood oxygenation data.
Innovation Solution
A transabdominal fetal pulse oximetry system that uses multiple light sources and photodetectors to differentiate between maternal and fetal signals, performing filtering and pulse-oximetry computations to determine fetal blood oxygenation levels, with adaptive adjustments for signal quality and depth penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fetal heart rate monitoring is used as the primary monitoring method, then the monitoring system is simple and widely applicable, but the measurement precision of fetal blood oxygenation is insufficient leading to unnecessary C-sections
Solution Approach 1:
The patent segments the mixed optical signal into maternal and fetal components by detecting signals at two different wavelengths. The first wavelength (600-700nm) primarily detects maternal tissue, while the second wavelength (700-900nm) detects both maternal and fetal tissue. This segmentation allows extraction of the fetal-specific signal component, achieving precise fetal blood oxygenation measurement without requiring invasive procedures.
Solution Approach 2:
The patent uses optical absorption as an intermediary mechanism to indirectly measure fetal blood oxygenation. By shining light through the maternal abdomen and measuring absorption at different wavelengths, the system converts the invisible fetal blood oxygenation state into detectable optical signals. This intermediary approach enables non-invasive measurement that would otherwise require direct blood sampling.
2Reliability
If transabdominal light penetration is used to measure fetal signals, then non-invasive measurement is achieved, but the maternal tissue absorbs most of the light signal reducing fetal signal detection
Solution Approach 1:
The patent changes the wavelength parameter of the light source to overcome maternal tissue absorption. By using two different wavelength ranges (first: 600-700nm, second: 700-900nm), the system exploits the differential absorption characteristics of maternal and fetal tissues. The second wavelength range is specifically chosen because fetal hemoglobin absorbs differently at these wavelengths compared to maternal hemoglobin, enabling reliable fetal signal detection despite maternal tissue attenuation.
Solution Approach 2:
The patent extracts the fetal signal from the mixed maternal-fetal optical signal by mathematical processing. The system measures the total absorption at two wavelengths, then uses the known absorption characteristics of maternal tissue at these wavelengths to calculate and subtract the maternal component, leaving only the fetal signal component. This extraction process recovers the fetal blood oxygenation information that was buried within the dominant maternal signal.
3Measurement precision
If multiple wavelengths are used to differentiate maternal and fetal signals, then fetal signal extraction is improved, but the device complexity and computational requirements increase
Solution Approach 1:
The patent uses wavelength as a discriminating parameter to differentiate maternal and fetal signals. By selecting two specific wavelength ranges where maternal and fetal hemoglobin have different absorption coefficients, the system creates a mathematical system that can be solved to separate the two signals. This parameter-based differentiation approach is more straightforward than temporal or spatial separation methods, reducing overall system complexity.
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
Provides accurate and robust measurement of fetal blood oxygenation, reducing the need for unnecessary C-sections and associated complications by offering a more precise monitoring of fetal health.
Implementation Method 1
The disclosed embodiments provide techniques for measuring blood-oxygen saturation by performing calculations based on the Beer-Lambert Law
Implementation Method 2
The system performs a pulse-oximetry computation on the fetal signal to determine the fetal blood oxygenation level
Implementation Method 3
receives a maternal signal from a first photodetector, which is positioned on the maternal abdomen to receive reflected light
Implementation Method 4
the system performs a filtering operation that removes maternal signal components from the mixed signal to produce a fetal signal
Data Source
AI summary
The system determines a fetal blood oxygenation level by activating two or more light sources, having different wavelengths, which are positioned on the maternal abdomen of a pregnant mammal to direct light into a maternal abdomen toward a fetus. The system then receives a maternal signal from a first photodetector, which is positioned on the maternal abdomen to receive reflected light that traverses maternal tissue. The system also receives a mixed signal from a second photodetector, which is positioned on the maternal abdomen to receive reflected light that traverses both maternal and fetal tissue. The system performs a filtering operation that removes maternal signal components from the mixed signal to produce a fetal signal. The system determines the fetal blood oxygenation level by performing a pulse-oximetry computation on the fetal signal. The system dynamically adjusts operational parameters in the face of changing variables, such as fetus position and depth.