Transabdominal Fetal Pulse Oximetry Signal Filtering
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Solution Overview
Problem
Current methods for monitoring fetal health during labor, such as cardiotocography, have a high false-positive rate, leading to unnecessary C-sections and increased health risks, highlighting the need for a more reliable and non-invasive technique to assess fetal well-being.
Innovation Solution
A transabdominal fetal pulse oximetry system that uses multiple light sources and photodetectors to measure fetal blood oxygenation levels by filtering out maternal signal components and performing pulse-oximetry computations, incorporating dynamic weighted averaging and external sensors for maternal and uterine contraction data to produce a composite fetal signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cardiotocography is used to monitor fetal well-being, then fetal heart rate can be tracked, but the false-positive rate is high leading to unnecessary C-sections
Solution Approach 1:
The patent extracts and measures the specific physiological parameter of fetal blood oxygenation level separately from general heart rate monitoring. By using photodetectors to measure light absorption at different wavelengths, the system isolates the oxygenation metric that directly indicates fetal well-being, rather than relying solely on heart rate patterns that produce false alarms.
Solution Approach 2:
The patent introduces light as an intermediary substance that penetrates maternal tissue to reach and interact with fetal blood. The light absorption properties of oxygenated and deoxygenated hemoglobin serve as a mediator to indirectly measure fetal oxygenation levels non-invasively, providing a more reliable indicator than direct heart rate monitoring.
2Ease of operation
If transabdominal light sources are used to measure fetal oxygenation, then non-invasive monitoring is achieved, but maternal tissue absorbs and scatters light reducing signal quality
Solution Approach 1:
The patent segments the optical measurement into multiple discrete wavelengths, each providing different information about tissue and blood properties. By using multiple photodetectors at different locations on the maternal abdomen, the system divides the measurement task across multiple channels, allowing computational separation of maternal and fetal signals to improve precision.
Solution Approach 2:
The patent adds the dimension of spatial distribution by placing multiple photodetectors at different locations on the maternal abdomen. This spatial dimension allows the system to distinguish between light that has traveled through maternal tissue only versus light that has reached fetal blood, enabling separation of maternal and fetal signals to improve 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
Provides a more objective and reliable metric for fetal well-being, reducing unnecessary C-sections and improving fetal outcomes by accurately determining fetal blood oxygenation levels through a non-invasive and robust clinical-grade monitoring system.
Implementation Method 1
activates two or more light sources, having different wavelengths, which are positioned on the abdomen of a pregnant mammal to direct light into the maternal abdomen toward a fetus
Implementation Method 2
determines the fetal blood oxygenation level by performing a pulse-oximetry computation based on the composite fetal signal
Data Source
AI summary
The disclosed system determines a fetal blood oxygenation level. During operation, the system activates two or more light sources, having different wavelengths, which are positioned on the abdomen of a pregnant mammal to direct light into the maternal abdomen toward a fetus. Next, the system receives a set of mixed signals from a set of photodetectors, which are positioned at different locations on the maternal abdomen to receive reflected light that traverses both maternal and fetal tissue. The system then performs a filtering operation that removes signal components associated with a maternal heart rate and a maternal respiration rate from the set of mixed signals to produce a set of fetal signals. Next, the system combines the set of fetal signals to produce a composite fetal signal. Finally, the system determines the fetal blood oxygenation level by performing a pulse-oximetry computation based on the composite fetal signal.