Cardiac Event Verification Using O2 Variation Index Trends
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Solution Overview
Problem
Implantable medical devices face challenges in accurately detecting cardiac events due to noise interference from patient movement, which affects the reliability of optical hemodynamic sensors used to monitor blood oxygen saturation levels.
Innovation Solution
The implementation of an optical hemodynamic sensor system that generates an O2 variation index trend using multiple wavelengths, allowing for secondary confirmation of cardiac events by distinguishing between noise-induced variations and actual hemodynamic instability, thereby improving the accuracy of therapy delivery in implantable medical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical hemodynamic sensors are used to monitor blood oxygen saturation levels, then the ability to detect cardiac events and respond to metabolic state changes is improved, but the reliability of detection deteriorates due to motion-induced noise
Solution Approach 1:
The patent introduces an intermediary verification process that uses multiple physiological parameters (ECG, impedance, oxygen saturation) as mediators to confirm cardiac events. Instead of relying solely on oxygen saturation data which is susceptible to motion noise, the system uses these intermediary signals to validate whether a detected event is genuine or artifact-induced, thereby resolving the reliability issue
Solution Approach 2:
The system changes the parameter verification approach by transitioning from single-parameter (oxygen saturation) detection to multi-parameter verification. It monitors multiple physiological parameters simultaneously and requires consistent changes across these parameters to confirm a cardiac event, thereby filtering out motion-induced noise that typically affects only one parameter
2Measurement precision
If multiple physiological parameters are monitored to verify cardiac events, then the accuracy of detection is improved, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by using a single implantable device to perform multiple sensing functions simultaneously. The device integrates ECG electrodes, impedance sensing capabilities, and oxygen saturation monitoring in one system, allowing it to collect multiple physiological parameters without requiring separate devices. This universal approach improves detection accuracy while managing device complexity through integration
Solution Approach 2:
The system merges multiple sensing modalities (electrical sensing via ECG, impedance measurement, and optical oxygen saturation monitoring) into a unified verification process. By combining these different types of measurements and requiring their convergence to confirm cardiac events, the system achieves high measurement precision while using a single integrated device rather than multiple separate systems
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
Enhances the reliability of cardiac event detection by differentiating between noise and hemodynamic instability, leading to more precise delivery of therapies such as cardioversion-defibrillation shocks, reducing unnecessary interventions and improving patient outcomes.
Implementation Method 1
emits light through a blood perfused tissue of the patient and a light detector for generating a signal representative of an intensity of light transmitted through the blood perfused tissue to the light detector
Implementation Method 2
a photodiode configured to detect light received through the lens of the housing
Data Source
AI summary
A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a plurality of sensors sensing cardiac signals, and a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals. A microprocessor detects a cardiac event in response to the sensed cardiac signals, computes a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determines a rate of change of the computed variation index trend, and confirms the determined cardiac event in response to the computed variation index trend and in response to the determined rate of change.