EIT Lung Ventilation and Cardiac Blood Flow Separation
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Solution Overview
Problem
Current methods for measuring stroke volume and tidal volume are invasive, discontinuous, or inaccurate due to the difficulty in separating cardiac blood flow from lung ventilation in time series voltage data, especially in non-intubated patients and during long-term monitoring.
Innovation Solution
The method employs Principal Component Analysis (PCA) and Independent Component Analysis (ICA) to extract shape-reference voltage waveforms for lung ventilation and cardiac blood flow from time series voltage data, allowing for the decomposition and continuous, non-invasive measurement of tidal volume and stroke volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EIT technology reconstructs image data first and then separates lung ventilation and cardiac blood flow components, then image reconstruction is achieved, but data loss or distortion occurs and accurate separation of cardiac blood flow component becomes difficult
Solution Approach 1:
The patent applies preliminary action by separating the lung ventilation component and cardiac blood flow component from the time series voltage data before image reconstruction. This is achieved through signal processing techniques that decompose the composite voltage signal into distinct physiological components, allowing each to be reconstructed separately without the data loss that occurs when attempting to separate components after full image reconstruction.
2Measurement precision
If transpulmonary thermodilution method is used to measure stroke volume, then stroke volume measurement is achieved, but catheter insertion is required and continuous measurement is not possible
Solution Approach 1:
The patent replaces the mechanical catheter-based TPTD system with an electrical field-based EIT system. Instead of physically inserting a catheter with temperature sensors, the system uses external electrodes to apply electrical currents and measure voltage changes, substituting a non-invasive electrical measurement approach for the invasive mechanical approach while enabling continuous monitoring.
3Measurement precision
If mask-based tidal volume measurement is used for non-intubated patients, then tidal volume measurement is achieved, but long-term monitoring becomes difficult
Solution Approach 1:
The patent enables self-service monitoring by using the patient's own body as the measurement medium. The EIT system uses electrodes placed on the chest that continuously measure electrical impedance changes caused by natural breathing and cardiac movements, eliminating the need for external masks or equipment that require manual adjustment and intervention for long-term monitoring.
4Measurement precision
If stroke volume and tidal volume are measured through different invasive or constraining means, then both parameters can be measured, but integrated cardiopulmonary function monitoring is not achieved
Solution Approach 1:
The patent merges the measurement of stroke volume and tidal volume into a single integrated EIT system. By placing multiple electrodes around the chest and analyzing the composite voltage signals using signal separation techniques, the system simultaneously extracts both cardiac and respiratory components from the same measurement setup, eliminating the need for separate catheters, masks, or monitoring devices.
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 enables precise, simultaneous, and continuous measurement of tidal volume and stroke volume, effectively monitoring cardiopulmonary function by reconstructing images from decomposed voltage data, improving accuracy and reducing invasiveness.
Implementation Method 1
a current is injected through a plurality of electrical impedance tomography (EIT) electrodes attached to the chest of a patient, voltage data corresponding to the injected current are measured
Data Source
AI summary
The present invention relates to an apparatus and a method of noninvasively separating and measuring a lung ventilation component and a cardiac blood flow component, and more specifically, to an apparatus and a method for extracting shape-reference voltage waveforms associated with lung ventilation and cardiac blood flow through principal component analysis (PCA) and independent component analysis (ICA), respectively, from time series voltage data acquired from a subject, decomposing the lung ventilation component and the cardiac blood flow component for each voltage channel using the extracted shape-reference voltage waveforms, thereby noninvasively, simultaneously, and continuously measuring tidal volume and stroke volume, respectively, from the decomposed lung ventilation component and cardiac blood flow component.