Regional Lung Compliance via Electrical Impedance Tomography
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Solution Overview
Problem
Existing methods struggle to determine regional lung compliance during spontaneous respiration due to the elastic restoration forces of the lung and diaphragm activity, making it difficult to assess lung state and adjust ventilation parameters effectively.
Innovation Solution
A method and system using electrical impedance tomography (EIT) to capture electrical impedance distributions across the thorax, dividing them into EIT pixels, and calculating regional compliance by analyzing impedance differences and assigning pixels to impedance value ranges, while also determining lung compliance through inspiration maneuvers and pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compliance measurement is performed during spontaneous respiration, then clinical relevance is improved, but measurement precision deteriorates due to elastic restoration forces and diaphragm activity
Solution Approach 1:
The patent uses an intermediary system consisting of EIT sensors and a control unit to indirectly measure compliance by detecting impedance changes during spontaneous respiration, rather than directly measuring compliance which would be affected by elastic restoration forces and diaphragm activity. This intermediary approach allows compliance determination while the patient breathes spontaneously.
Solution Approach 2:
The patent replaces direct mechanical compliance measurement with an electrical impedance-based measurement system. By substituting the mechanical measurement approach with an electrical field-based EIT system, the method enables compliance assessment during spontaneous respiration without being disrupted by mechanical forces from the diaphragm and lung elasticity.
2Loss of information
If regional compliance determination is implemented, then information quality is improved, but device complexity increases due to EIT integration
Solution Approach 1:
The patent integrates multiple functions into a single EIT-based system: the same EIT sensors and processing unit are used for both capturing electrical impedance distributions and determining regional compliance. This multi-functional approach reduces overall device complexity despite the advanced capabilities provided.
Solution Approach 2:
The patent divides the lung into multiple EIT pixels to provide spatially differentiated information. By segmenting the lung into discrete measurement points, the system achieves detailed regional compliance mapping while using a relatively simple EIT sensor array, avoiding the need for complex multi-sensor systems.
3Difficulty of detecting and measuring
If EIT is used for compliance measurement, then measurement capability is improved, but ease of operation deteriorates due to complex data processing
Solution Approach 1:
The control unit automatically performs the complex data processing required for regional compliance determination. The system self-services by taking the raw EIT impedance data and automatically calculating regional compliance values without requiring manual intervention or complex user operations, thus maintaining ease of operation despite the sophisticated measurements performed.
Solution Approach 2:
The system provides feedback by automatically processing EIT data and generating regional compliance information that can be used to adjust ventilation parameters. This closed-loop feedback approach simplifies operation by automatically translating complex impedance measurements into actionable clinical information.
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
Enables accurate determination of regional lung compliance during spontaneous respiration, providing clinically relevant information for assessing lung inhomogeneity and adjusting ventilation parameters to spare lung tissue effectively.
Implementation Method 1
capturing an electrical impedance distribution along at least one two-dimensional section through a human thorax by means of a device for electrical impedance tomography
Implementation Method 2
By contrast, this is not the case during spontaneous respiration on account of the elastic restoration forces of the lung and the diaphragm activity
Data Source
AI summary
A method for determining a regional compliance of a lung during spontaneous respiration. In the method, a lung compliance value C.M is determined by triggering an inspiration maneuver and either measuring a compliance of the entire lung or of a surrogate for the compliance of the entire lung. In the method, there further is a capture of an electrical impedance distribution along at least one two-dimensional section through a human thorax by a device for electrical impedance tomography, with a multiplicity of EIT pixels being captured. An end-inspiratory and an end-expiratory electrical impedance are determined for each EIT pixel and an impedance difference is determined for each EIT pixel. The regional compliance is determined for specific EIT pixels, which are assigned to an impedance value range based on a frequency distribution of all EIT pixels.