ECAP Signal Derivative Analysis for Electrode-Nerve Distance Compensation
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Solution Overview
Problem
Existing medical devices struggle to accurately adjust electrical stimulation therapy parameters in response to changes in the distance between implanted electrodes and target nerves due to movement, leading to ineffective therapy or side effects.
Innovation Solution
An implantable medical device analyzes evoked compound action potential (ECAP) signals to determine invariant characteristics, such as maximum and minimum values of the derivative, to adjust stimulation parameters and maintain effective therapy despite changes in electrode-nerve distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electrical stimulation therapy is delivered with fixed parameters, then the device structure remains simple, but the therapeutic efficacy deteriorates when electrode-nerve distance changes due to patient movement
Solution Approach 1:
The system continuously monitors ECAP signals and uses this feedback to automatically adjust stimulation parameters. The processing circuitry analyzes the ECAP signal characteristics and modifies stimulation parameters accordingly, creating a closed-loop control system that maintains therapeutic efficacy despite electrode-nerve distance changes
Solution Approach 2:
The system dynamically changes stimulation parameters (amplitude, frequency, pulse width) based on real-time ECAP signal analysis. When ECAP characteristics indicate changed electrode-nerve distance, the processing circuitry adjusts parameters to compensate, ensuring consistent therapeutic effect
2Reliability
If ECAP signal characteristics are used for parameter adjustment, then therapeutic efficacy is maintained, but measurement precision requirements increase due to noise and artifacts
Solution Approach 1:
The system extracts and analyzes specific invariant characteristics from the ECAP signal, such as the area between positive and negative peaks or the time difference between peaks. By focusing on these specific features that remain consistent despite noise and artifacts, the system achieves reliable parameter adjustment without requiring perfect signal quality
Solution Approach 2:
The system uses ECAP signal analysis to anticipate and compensate for parameter adjustments before significant therapeutic degradation occurs. By continuously monitoring and preparing parameter modifications based on ECAP trends, the system maintains therapy effectiveness proactively rather than reactively
Data Source
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AI summary
Systems, devices, and techniques are described for analyzing evoked compound action potentials (ECAP) signals to assess the effect of a delivered electrical stimulation signal. In one example, a system includes a stimulation generator configured to deliver a stimulation pulse to a patient, sensing circuitry configured to sense an evoked compound action potential (ECAP) signal evoked from the stimulation pulse, and processing circuitry. The processing circuitry may be configured to determine a maximum value of a derivative of the ECAP signal, determine a minimum value of the derivative of the ECAP signal, determine, based on the maximum value of the derivative and the minimum value of the derivative, a characteristic value of the ECAP signal, and determine, based on the characteristic value of the ECAP signal, at least one parameter value at least partially defining electrical stimulation therapy to be delivered to the patient.