Optical Hemodynamic Sensor Motion Noise Filtering
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Solution Overview
Problem
Optical hemodynamic sensors used in medical devices are susceptible to motion noise, limiting their practical application in detecting hemodynamically unstable arrhythmias due to signal corruption.
Innovation Solution
A medical device with a processor that analyzes signals from a multiple wavelength optical hemodynamic sensor, assessing baseline and current motion levels to differentiate between motion-induced noise and hemodynamic instability, allowing for accurate detection of arrhythmias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical hemodynamic sensors are used to detect arrhythmias, then hemodynamic function data can be obtained, but motion noise corrupts the output signal
Solution Approach 1:
The system performs preliminary motion assessment by analyzing the optical signal during an initial time period to establish a baseline motion level before proceeding to arrhythmia detection. This preliminary action allows the system to prepare appropriate filtering parameters in advance, improving detection reliability while accounting for motion conditions.
Solution Approach 2:
The system dynamically adjusts detection parameters based on motion levels. When motion exceeds the baseline threshold, the system modifies its analysis approach or ignores the signal during high-motion periods. This parameter adaptation resolves the contradiction by allowing reliable detection during low-motion periods while mitigating motion noise effects during high-motion periods.
2Measurement precision
If motion assessment is performed continuously, then motion noise can be filtered, but device complexity increases
Solution Approach 1:
The system performs motion assessment selectively rather than continuously - specifically during initial time periods when baseline motion needs to be established, and at subsequent time periods when arrhythmia detection is needed. This partial action approach maintains signal accuracy while avoiding the excessive processing complexity of continuous motion monitoring.
Solution Approach 2:
The detection process is segmented into distinct time periods: an initial time period for baseline motion assessment and subsequent time periods for arrhythmia detection. This segmentation allows the system to apply different processing strategies to different segments, improving signal accuracy without requiring complex continuous processing throughout the entire monitoring period.
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
The device effectively identifies hemodynamically unstable arrhythmias by filtering out motion noise, ensuring reliable detection and potential therapy delivery, even in conditions where patient movement is minimal.
Implementation Method 1
a light source for transmitting a plurality of optical signals into body tissue of a patient and a light detector for receiving the plurality of signals as attenuated by transmission through the body tissue
Data Source
AI summary
A medical device identifies a hemodynamically unstable arrhythmia based upon optical hemodynamic sensor signals. The optical hemodynamic sensor includes a light source for transmitting light corresponding to first and second wavelengths through a blood perfused tissue of a patient and a light detector for generating optical signals corresponding to an intensity of the detected light at the first and second wavelengths. At a low motion period for the patient, optical signals are obtained from the optical hemodynamic sensor and are analyzed to determine a baseline motion level for the patient. Subsequent signals obtained from the optical hemodynamic sensor are compared to the baseline motion levels, with only those signals corresponding to periods where motion does not exceed the baseline level of motion being further analyzed to determine if they are consistent with a hemodynamically unstable arrhythmia.