Closed-loop stimulation sensing with periodic signal polling
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Solution Overview
Problem
Medical devices face challenges in accurately sensing biomarker signals due to interference from electrical stimulation therapy, which can confound or suppress the signals used for feedback in closed-loop therapy, making it difficult to adjust therapy parameters effectively.
Innovation Solution
A system that delivers electrical stimulation in two different patient states and determines if there is a difference in biomarker signals, allowing the medical device to select a therapy mode based on whether the signals are impacted, using a polling closed-loop therapy mode when signals are suppressed and a normal closed-loop therapy mode when signals are not, by temporarily ceasing therapy to allow biomarker signals to return to normal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation therapy is delivered continuously to treat patient conditions, then therapeutic effectiveness is improved, but the ability to accurately sense biomarker signals is worsened due to signal suppression or interference
Solution Approach 1:
The system implements periodic action by temporarily suspending electrical stimulation therapy at defined intervals to allow biomarker signals to return to baseline levels. This periodic interruption enables accurate signal sensing during therapy, as the suspension creates windows where endogenous biomarker signals are not suppressed by ongoing stimulation, thus resolving the contradiction between continuous therapy delivery and accurate biomarker detection
Solution Approach 2:
The system maintains continuity of useful action by rapidly alternating between therapy delivery and signal sensing modes. The brief suspensions of therapy are minimized in duration and frequency, allowing the system to maintain predominantly continuous therapeutic effect while periodically capturing accurate biomarker signals. This approach ensures that therapy remains effective over time while obtaining sufficient data points for closed-loop control
2Reliability
If electrical stimulation is delivered to achieve therapeutic effects, then patient condition improvement is enhanced, but detection of biomarker signals becomes more difficult due to signal confounding
Solution Approach 1:
The system applies the extraction principle by separating the therapy delivery function from the signal sensing function in time. During designated sensing intervals, electrical stimulation is completely suspended and removed from the system, allowing pure biomarker signal detection without contamination from stimulation artifacts. This temporal extraction enables the sensing subsystem to operate independently without interference from the stimulation subsystem
Solution Approach 2:
The system implements preliminary action by proactively suspending therapy delivery before attempting to sense biomarker signals. Rather than trying to distinguish signals from ongoing stimulation, the system preemptively removes the stimulation source, ensuring that when sensing occurs, the biomarker signals are already free from confounding effects. This preliminary suspension prevents signal contamination rather than attempting to correct it afterward
3Adaptability or versatility
If closed-loop therapy adjustment is implemented based on biomarker signals, then therapy optimization is improved, but signal suppression from ongoing stimulation prevents accurate feedback
Solution Approach 1:
The system implements feedback by using the periodically sensed biomarker signals to dynamically adjust therapy parameters. During suspension intervals when signals are accurately detected, the system analyzes biomarker levels and uses this information to optimize subsequent therapy delivery. This closed-loop feedback mechanism enables therapy adaptation while overcoming signal suppression through strategic timing of measurements during suspension periods when signal integrity is restored
Data Source
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AI summary
An example system includes stimulation generation circuitry configured to deliver electrical stimulation to a patient; sensing circuitry configured to sense one or more biomarker signals; and processing circuitry configured to: cause delivery of electrical stimulation with the patient in a first patient state; receive a first instance of a biomarker signal in presence of the electrical stimulation with the patient in the first patient state; cause delivery of electrical stimulation with the patient in a second patient state; receive a second instance of the biomarker signal in presence of the electrical stimulation with the patient in the second patient state; determine whether a difference between the first instance of the biomarker signal and the second instance of the biomarker signal satisfies a threshold; select a therapy mode based on whether the difference satisfies the threshold; and cause delivery of electrical stimulation in accordance with the selected therapy mode.