Hysteresis Algorithm for Implantable Impedance Monitoring
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Solution Overview
Problem
Existing impedance monitoring systems face challenges in accurately determining when to notify patients of abnormal fluid status, leading to either missed serious conditions or unnecessary resource consumption due to false positives.
Innovation Solution
A method involving the use of implantable medical devices to collect and analyze impedance data by establishing baseline and short-term average impedance values, with a hysteresis-based algorithm to differentiate between normal and abnormal fluid levels, reducing false positives by adjusting the notification threshold and hysteresis value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the notification threshold is set to be highly sensitive to detect all abnormal fluid status, then detection sensitivity is improved, but false positives increase leading to unnecessary resource consumption
Solution Approach 1:
The patent applies parameter changes by introducing a hysteresis value that modifies the notification threshold dynamically. When impedance indicates abnormal fluid status, the notification threshold adjusts by adding the hysteresis value, making subsequent notifications require a greater change. This resolves the contradiction by maintaining high initial sensitivity to detect all abnormalities while reducing false positives through adaptive threshold modification, thereby balancing detection sensitivity with resource conservation.
2Loss of energy
If the notification threshold is set to reduce false positives, then resource consumption is optimized, but detection sensitivity decreases leading to missed serious conditions
Solution Approach 1:
The patent implements preliminary action by establishing a baseline impedance value before notifications begin. This baseline serves as a reference point that enables the system to detect deviations indicating abnormal fluid status. By having this preliminary measurement in place, the system can maintain high detection sensitivity from the start while using the hysteresis mechanism to prevent false positives, thus optimizing resources without missing serious conditions.
3Device complexity
If impedance monitoring uses fixed threshold values for patient notification, then device complexity is minimized, but adaptability to individual patient variations deteriorates
Solution Approach 1:
The patent applies dynamics by transforming fixed threshold values into adaptive thresholds that respond to individual patient characteristics. The notification threshold dynamically adjusts based on the baseline impedance specific to each patient and incorporates a hysteresis value that modifies the threshold based on current impedance readings. This resolves the contradiction by maintaining relatively simple device complexity while achieving high adaptability to individual patient variations through dynamic threshold adjustment.
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 effectively reduces false positives while maintaining sensitivity, allowing for timely patient notification and resource optimization by using a hysteresis-based algorithm to analyze impedance data from implantable medical devices.
Implementation Method 1
Impedance monitoring is often used with implantable medical devices and in external monitoring devices for determination of numerous physiologic conditions. Transthoracic impedance measurements can give a good indication of the fluid status of patients
Data Source
AI summary
Adaptations to the OptiVol™ alert algorithm are disclosed which may reduce the number of false positive alerts while retaining the desired sensitivity. Some embodiments monitor fluid levels in patients. Some embodiments reset a cumulative index when a short-term impedance value is greater than a baseline impedance value minus a predetermined positive hysteresis value.