Noninvasive Pulmonary Ventilation Measurement via Body Surface Displacement
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Solution Overview
Problem
Conventional methods for measuring pulmonary ventilation are invasive, uncomfortable, and inaccurate, especially in varying postures or during sleep, due to limitations in two- and three-degrees-of-freedom models that fail to accurately account for spinal flexion and posture changes.
Innovation Solution
A noninvasive method and system that determines tidal volume by measuring linear displacements of the rib cage, abdomen, and axial chest wall, using a combination of sensors and mathematical relationships to account for volume-motion coefficients in different orientations and motions, thereby reducing errors associated with conventional models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mouthpiece connected to a flow rate measuring device is used to measure pulmonary ventilation, then accurate measurement of air volume can be achieved, but the method becomes invasive, uncomfortable, and difficult to use for long term monitoring
Solution Approach 1:
The patent extracts the measurement function from the invasive mouthpiece approach and implements it through noninvasive body surface measurements using magnetometers and RIP belts, eliminating the need for oral insertion while preserving ventilation measurement capability
Solution Approach 2:
The patent replaces the mechanical mouthpiece-flow rate measuring device system with a magnetic field-based measurement system using magnetometers and inductive plethysmography, substituting direct air flow measurement with indirect body surface motion measurement
2Ease of operation
If qualitative respiration monitors without mouthpiece are used, then ease of operation is improved, but measurement accuracy of air volume deteriorates
Solution Approach 1:
The patent employs calibration procedures that establish relationships between body surface measurements and actual ventilation values, using feedback loops to adjust volume-motion coefficients and improve measurement accuracy over time
Solution Approach 2:
The patent transforms the measurement approach by changing from direct air flow parameters to body surface displacement parameters, using mathematical relationships and volume-motion coefficients to convert positional data into accurate ventilation measurements
3Device complexity
If two-degrees-of-freedom models are used to measure rib cage and abdomen displacement, then device complexity is reduced, but measurement accuracy deteriorates in varying postures and during sleep
Solution Approach 1:
The patent adds a third degree of freedom by incorporating axial chest wall displacement measurements alongside rib cage and abdomen measurements, transitioning from two-dimensional to three-dimensional body surface monitoring to accurately capture spinal flexion and posture changes
Solution Approach 2:
The patent implements dynamic calibration and real-time adjustment of volume-motion coefficients based on detected posture changes, allowing the system to adapt to varying positions and motions rather than relying on static two-degree-of-freedom assumptions
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
The method provides accurate and continuous measurement of pulmonary ventilation in various postures and during sleep, significantly reducing errors to within 10% of actual ventilation, and effectively detects respiratory abnormalities such as apneas and hypopneas.
Implementation Method 1
respiratory magnetometers consist of tuned pairs of electromagnetic coils or magnetometers; one coil being adapted to transmit a specific high frequency AC electromagnetic field (i.e. transducer) and the other coil (i.e. receiver) being adapted to receive the field
Implementation Method 2
the output voltage is linearly related to the distance between a pair of coils; provided, the axes of the coils or magnetometers remain parallel to each other
Data Source
AI summary
A pulmonary ventilation system comprising a method to determine at least one pulmonary ventilation parameter as a function of a plurality of measured anatomical distances and volume-motion coefficients, sensors for acquiring the anatomical distances, a device for determining the plurality of motion coefficients, and a device for determining the ventilation parameter based on the acquired anatomical distances and determined plurality of volume-motion coefficients. In one embodiment, the system further includes a method for acquiring base-line ventilation characteristics and a method for correlating the base-line ventilation characteristics to the ventilation parameter determined with the empirical relationship.