ECAP-Based Stimulation Control for Posture-Adaptive Therapy
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Solution Overview
Problem
Medical devices delivering electrical stimulation face challenges in maintaining effective therapy due to changes in patient posture, which alter the distance between electrodes and target nerves, leading to varying levels of neural recruitment and sensitivity to stimulation parameters.
Innovation Solution
A system that senses evoked compound action potential (ECAP) signals to determine the posture state of a patient and adjusts stimulation parameters such as amplitude, frequency, and pulse shape using gain values and growth curves to maintain optimal neural recruitment and prevent discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is delivered using fixed parameters, then the device operation is simple, but the therapeutic efficacy varies with posture changes
Solution Approach 1:
The system senses ECAP signals from the patient's tissue and uses this feedback to automatically adjust stimulation parameters. The processing circuitry compares the sensed ECAP characteristic values against target values and modifies pulse amplitude, width, or frequency accordingly, maintaining consistent neural recruitment despite posture changes.
Solution Approach 2:
The stimulation parameters are made dynamic rather than fixed. The system continuously monitors ECAP signals and adjusts stimulation delivery in real-time based on detected changes in neural response, allowing the therapy to adapt to varying electrode-tissue distances caused by posture changes.
2Reliability
If stimulation parameters are adjusted to compensate for posture changes, then therapeutic efficacy is maintained, but the system complexity increases
Solution Approach 1:
The system performs self-adjustment by automatically sensing ECAP signals and modifying its own stimulation parameters without external intervention. The processing circuitry autonomously determines when parameter changes are needed based on ECAP feedback, reducing the need for manual programming or external control systems.
Solution Approach 2:
Closed-loop control using ECAP feedback enables the system to self-regulate stimulation intensity. By continuously monitoring the neural response and adjusting parameters to maintain a target ECAP characteristic value, the system maintains therapeutic efficacy while automating the complexity of parameter management.
3Reliability
If high amplitude stimulation is used to ensure therapeutic effect, then pain relief is effective, but patient discomfort increases
Solution Approach 1:
The system uses ECAP signal feedback to precisely control the amount of neural recruitment. By adjusting stimulation parameters to achieve a target ECAP characteristic value, the system delivers the minimum effective stimulation needed for pain relief while avoiding excessive intensity that would cause discomfort or overstimulation.
Solution Approach 2:
Rather than relying solely on high amplitude, the system modifies multiple stimulation parameters including pulse width, frequency, and amplitude to achieve effective therapy. This multi-parameter approach allows fine-tuning of neural recruitment to provide adequate pain relief at lower intensities, reducing patient discomfort.
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 system ensures consistent therapeutic efficacy by dynamically adjusting stimulation parameters based on posture changes, preventing overstimulation and maintaining effective pain relief without unacceptable side effects.
Implementation Method 1
sensing circuitry configured to sense an evoked compound action potential (ECAP) signal elicited by delivered electrical stimulation
Data Source
AI summary
Systems, devices, and techniques for adjusting electrical stimulation based on a posture state of a patient are described. For example, a system may include sensing circuitry configured to sense an ECAP signal and processing circuitry configured to control delivery of the electrical stimulation to a patient according to a first value of a stimulation parameter and determine a characteristic value of the ECAP signal. The processing circuitry may also be configured to receive, from a sensor, a posture state signal representing a posture state of the patient, determine, based on the posture state signal, a gain value for the stimulation parameter, adjust, based on the characteristic value of the ECAP signal and the gain value, the first value of the stimulation parameter to a second value of the stimulation parameter, and control delivery of the electrical stimulation according to the second value of the stimulation parameter.