Dynamically Variable Filter for Bioimpedance Signal Processing
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Solution Overview
Problem
Current methods for measuring cardiac output and other physiological parameters, such as thoracic electrical bioimpedance, face challenges in accurately filtering signals to distinguish relevant from irrelevant physiological data, especially in dynamic conditions like patient agitation or breathing, leading to noise interference and reduced accuracy.
Innovation Solution
A method and system that dynamically adapt the frequency band of filters in response to changes in physiological conditions, such as heart rate, to improve signal processing and reduce noise, using a band pass filter with frequency bounds that are linear functions of heart rate, and employing techniques like phase shift determination and amplitude modulation reduction to enhance signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed frequency band filter is used to process bioimpedance signals, then the device complexity is reduced, but the measurement precision deteriorates under dynamic physiological conditions
Solution Approach 1:
The patent implements a dynamically adjustable frequency band filter where the passband frequencies are automatically adapted based on detected physiological parameters (such as heart rate). This allows the filter to track and maintain optimal frequency ranges for different physiological states, thereby improving signal-to-noise ratio without requiring manual intervention or complex fixed multi-filter systems.
Solution Approach 2:
The filter's frequency parameters (lower and upper cutoff frequencies) are changed dynamically based on physiological conditions. The system calculates appropriate frequency bounds as functions of measured physiological parameters, allowing the filter characteristics to adapt to varying physiological states such as different heart rates or respiratory patterns, thus maintaining measurement precision across diverse conditions.
2Adaptability or versatility
If the frequency band is widened to capture more physiological information, then the adaptability is improved, but the noise interference increases
Solution Approach 1:
The system dynamically adjusts the frequency band parameters based on the detected physiological state. When physiological conditions change (e.g., heart rate increases), the filter's frequency bounds are recalculated to appropriately expand or contract the passband, ensuring that relevant physiological signals are captured while excluding frequency ranges dominated by noise or artifacts.
Data Source
AI summary
A method of processing a signal pertaining to at least one electrical property of an organ of a subject is disclosed. The method comprises determining a physiological condition of the subject, selecting a frequency band, filtering the signal according to the frequency band, and dynamically adapting the frequency band in response to a change in the physiological condition.