Nasal Cavity Model Calibration for Sleep Apnea Deformation

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Solution Overview

Problem

Current diagnostic methods for obstructive sleep apnea syndrome (OSAS) fail to accurately simulate the airway's deformation in a sleeping state, as they treat the upper airway as a non-deformable model, neglect surrounding tissues, and do not account for bidirectional airflow during respiration, leading to inadequate therapeutic outcomes.

Innovation Solution

A system that generates a nasal cavity model by extracting specific pixel density values from three-dimensional image data, adjusts these values to match actual nasal cavity resistance, and predicts airway deformation in a sleeping state using conversion equations derived from waking and sleeping state models, allowing for precise identification of obstructive sites.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the upper airway is simulated as a non-deformable rigid model, then fluid analysis can be executed, but elastic deformation of the upper airway cannot be simulated

Engineering Contradiction:

Improveease of fluid analysisVSAvoidsimulation accuracy

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent transforms the rigid airway model into a dynamic, deformable model that can change shape during respiration. The airway is modeled as a flexible structure that deforms in response to pressure changes and surrounding tissue movement, enabling realistic simulation of airway collapse and obstruction during sleep.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the physical parameters of the airway model from rigid to deformable by incorporating elastic properties and coupling with surrounding tissues. This allows the model to exhibit realistic deformation behavior under varying pressure conditions while maintaining computational feasibility through parameter optimization.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If only the upper airway is modeled without surrounding tissues, then modeling complexity is reduced, but deformation of surrounding tissues cannot be simulated

Engineering Contradiction:

Improvemodeling complexityVSAvoidsimulation accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent merges the airway model with surrounding tissue models into an integrated coupled system. The airway and surrounding tissues are modeled as interacting components where tissue deformation directly influences airway geometry and flow characteristics, providing comprehensive simulation of sleep apnea mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the respiratory system into distinct but coupled components: the airway lumen, surrounding soft tissues, and skeletal structures. Each segment is modeled with appropriate mechanical properties and coupled through boundary conditions, allowing detailed analysis of individual components while capturing their interactive deformation behavior.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If air flow is assumed to flow in one direction, then fluid analysis is simplified, but bidirectional airflow during respiration cannot be simulated

Engineering Contradiction:

Improvefluid analysis complexityVSAvoidrespiration simulation accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements periodic boundary conditions that simulate the cyclic nature of respiration with alternating inhalation and exhalation phases. The flow direction and pressure gradients vary periodically throughout the respiratory cycle, enabling realistic simulation of bidirectional airflow and its effect on airway deformation and obstruction patterns.

Inventive Principle:

Principle #19Periodic action

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 system effectively simulates the nasal cavity and upper airway deformation, enabling accurate specification of obstructive sites and improving therapeutic outcomes for OSAS by generating models that accurately reflect the airway's resistance and deformation in a sleeping state.

Implementation Method 1

three-dimensional image data obtained by an imaging device

Methodology Applied

Scientific EffectX-ray imaging: X-Ray

Implementation Method 2

a nasal cavity resistance through fluid analysis using the generated nasal cavity model

Methodology Applied

Scientific EffectFluid flow resistance: Drag

Data Source

PatentUS11432742B2Airway ventilation state calibration system and system for predicting airway deformation during sleep

Publication Date: 2022.09.06 UNIVERSITY OF TOKUSHIMA

AI summary

A nasal-cavity model generator (41) extracts pixels having pixel density values within a specific range from three-dimensional image data on a nasal cavity of a subject contained in DICOM data (21), and generates a nasal cavity model (50), which is a three-dimensional model of the nasal cavity, based on three-dimensional image data composed of the extracted pixels. A nasal-cavity resistance calculator (42) calculates a nasal cavity resistance (51) through fluid analysis using the nasal cavity model (50) generated by the nasal-cavity model generator (41). An adjuster (43) adjusts the specific range of the pixel density values of the pixels to be extracted for generation of the nasal cavity model (50) by the nasal-cavity model generator (41) such that the nasal cavity resistance (51) calculated by the nasal-cavity resistance calculator (42) is equal to a nasal cavity resistance (52) actually measured with a nasal-cavity draft gauge.