Implanted Posture Sensor for Accurate Pulmonary Edema Monitoring
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Solution Overview
Problem
Current methods for estimating left atrial pressure (LAP) using impedance measurements between implanted electrodes are prone to drift and imprecision due to factors unrelated to LAP, leading to inaccurate monitoring and potential delays in diagnosing conditions like pulmonary edema, which can be life-threatening.
Innovation Solution
Incorporating a posture sensor with an implantable device to stabilize impedance signal measurements by ensuring the patient maintains a predetermined posture for a specified period, allowing for more accurate calculation of zLAP and monitoring of LAP and intra-thoracic fluid volume, thereby improving diagnostic accuracy and timely intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If impedance measurements are used to estimate LAP, then non-invasive monitoring is achieved, but measurement precision deteriorates due to drift and imprecision from posture changes and other factors
Solution Approach 1:
The system continuously monitors posture using sensors (accelerometers, gyroscopes) and provides feedback to control the impedance measurement timing. When posture changes are detected, the system adjusts measurement scheduling to ensure accurate LAP estimation is only performed when the patient is in the required supine position, thereby resolving the contradiction between ease of non-invasive monitoring and measurement precision
Solution Approach 2:
The system performs preliminary posture assessment before initiating impedance measurements. By verifying the patient is in the correct supine posture and maintaining it for a specified duration before taking measurements, the system ensures measurement accuracy while continuing to offer non-invasive monitoring through the same implanted electrodes
2Productivity
If impedance measurements are taken continuously, then monitoring coverage is improved, but reliability deteriorates due to inclusion of inaccurate measurements from posture changes
Solution Approach 1:
Instead of continuous measurement, the system implements periodic measurement cycles that are gated by posture status. Impedance measurements are periodically taken only when posture sensors confirm the patient is in the required supine position, creating a rhythm of measurement that ensures reliability while maintaining comprehensive monitoring coverage through repeated valid measurements
Solution Approach 2:
The posture sensor provides continuous feedback about patient position, which controls the measurement scheduling algorithm. This feedback mechanism filters out unreliable measurements taken during posture transitions and ensures only accurate measurements are included in LAP estimation, maintaining both monitoring coverage and reliability
3Measurement precision
If posture monitoring is added to the implantable device, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The implantable device leverages existing multi-functional components already present for cardiac monitoring. The same electrodes used for ECG and cardiac rhythm monitoring are also utilized for impedance-based LAP estimation, while posture sensors (accelerometers/gyroscopes) serve dual purposes of fall detection and posture validation for measurement timing, thereby improving precision without proportionally increasing complexity
Solution Approach 2:
The system merges posture sensing capabilities with the existing cardiac monitoring architecture. By combining accelerometer and gyroscope data processing with the impedance measurement system, the patent integrates multiple functions into a unified control algorithm that schedules measurements based on posture, improving accuracy while minimizing additional hardware and software complexity
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 enhances the accuracy of LAP estimation and monitoring, enabling earlier detection of abnormalities and more effective treatment adjustments, potentially reducing complications from conditions like pulmonary edema.
Implementation Method 1
a posture sensor to detect when a patient changes from a first predetermined posture to a second predetermined posture
Implementation Method 2
measuring impedance (Z) between two or more implanted electrodes... impedance measurements are susceptible to drift and/or imprecision
Data Source
AI summary
In specific embodiments, a method to monitor pulmonary edema of a patient, comprises (a) detecting, using an implanted posture sensor, when a posture of the patient changes from a first predetermined posture to a second predetermined posture, (b) determining an amount of time it takes an impedance signal to achieve a steady state after the posture of the patient changes from the first predetermined posture to the second predetermined posture, where the impedance signal is obtained using implanted electrodes and is indicative of left atrial pressure and/or intra-thoracic fluid volume of the patient, and (c) monitoring the pulmonary edema of the patient based on the determined amount of time it takes the impedance signal to achieve the steady state after the posture of the patient changes from the first predetermined posture to the second pre-determined posture.