Pediatric Lung Clearance Index Measurement Without Flowmeter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multiple-breath wash-out (MBW) tests are challenging to perform in pediatric patients due to issues with response time and dead space, especially in small children and newborns, leading to inaccurate lung clearance index (LCI) measurements.
Innovation Solution
A method and system that allow pediatric patients to inhale an inert tracer gas via open circuit, bias flow, or rebreathing, with exhalation into a confined space, enabling the calculation of LCI without direct flow measurement, using a valve assembly and gas analyzers to monitor end-tidal concentrations, reducing the need for a flowmeter and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MBW tests are performed in pediatric patients using traditional flow measurement systems, then LCI can be calculated, but dead space increases and response time requirements become excessive
Solution Approach 1:
The patent removes the flowmeter from the measurement system entirely. Instead of measuring flow directly, the system calculates LCI using only gas concentration measurements from the confined space. This extraction of the flow measurement component eliminates the dead space associated with traditional flowmeters while maintaining LCI calculation capability through an alternative measurement approach.
Solution Approach 2:
The patent introduces a confined space as an intermediary between the patient's lungs and the measurement system. The confined space acts as a collection chamber where exhaled gases accumulate, allowing concentration measurements to be taken without requiring direct flow measurement. This intermediary enables accurate LCI determination while minimizing dead space requirements.
2Measurement precision
If conventional MBW tests are performed in pediatric patients with small lung volumes, then LCI can be determined, but response time requirements become excessively demanding
Solution Approach 1:
The patent replaces the mechanical flow measurement system with a gas concentration analysis system. Instead of using flowmeters that require rapid response to small flow changes in pediatric patients, the system uses gas analyzers to measure tracer gas concentrations in the confined space. This substitution eliminates the need for fast mechanical response while maintaining measurement accuracy for small lung volumes.
Solution Approach 2:
The patent creates a simplified measurement model where LCI is determined by measuring the concentration of tracer gas in the confined space rather than directly measuring complex flow dynamics. This copying approach uses concentration data to represent the ventilation clearance process, avoiding the need for rapid flow measurement response times.
3Quantity of substance
If flowmeters are used to measure respiratory flows in pediatric MBW tests, then expiratory flows and volumes can be recorded, but the system complexity and dead space increase
Solution Approach 1:
The patent extracts the volume measurement capability from the flowmeter and relocates it to the confined space. By measuring the total volume of gas collected in the confined space and combining this with tracer gas concentration data, the system determines expired volume without requiring a flowmeter. This extraction eliminates the complexity and dead space associated with flow measurement devices.
Solution Approach 2:
The confined space serves as an intermediary that collects and accumulates expired gases. By measuring the volume of gas in this confined space and the tracer gas concentration within it, the system calculates expired volume indirectly. This intermediary approach provides volume measurement capability without the complexity of direct flow measurement 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
This approach allows for accurate measurement of LCI in pediatric patients, reducing dead space and response time requirements, achieving superior accuracy compared to traditional systems, especially at lower lung volumes, and aligning with international guidelines.
Implementation Method 1
a gas analyser for obtaining the fractional concentration at the end of each breath of the inert tracer gas inhaled and exhaled by the paediatric test subject until the concentration has reached a predetermined fraction of the concentration in the beginning of the wash-out period
Data Source
AI summary
Methods and systems to determine the lung clearance index (LCI) or other indices of ventilation inhomogeneity of lungs of a paediatric subject are provided. Inert tracer gas is washed-in and the wash-out is conducted by inhaling atmospheric air from the surroundings and exhaling to a confined space until the end-tidal tracer gas concentration has fallen below a predetermined fraction of the starting concentration. The LCI is calculated as the ratio between the cumulative expired volume (VCE) required to clear the inert tracer gas concentration from the lungs below a predetermined fraction of the starting concentration and the functional residual capacity (FRC) determined by dividing the net volume of inert tracer gas exhaled with the difference in end-tidal fractional concentration of the inert tracer gas at the start and end of the wash-out period; where VCE is determined by measuring the total volume in the collection bag after completed wash-out period.