Pulse Wave Upstroke Analysis for Sleep Apnea Differentiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting and distinguishing between obstructive and central sleep apnea are limited by inaccuracies due to vascular tone variations and movement sensitivity, complicating the differentiation and treatment of these conditions.
Innovation Solution
A system for non-invasive detection based on analyzing circulatory pulse waveforms, specifically the systolic upstroke index, which is normalized to account for vascular tone changes and heart contraction strength, allowing differentiation between obstructive and central sleep apneas by monitoring changes in the upstroke index during breathing cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If respiratory modulation patterns of pulse signal envelopes are used to detect sleep disordered breathing, then detection capability is provided, but measurement precision deteriorates due to vascular tone variations and movement sensitivity
Solution Approach 1:
The patent transforms the analysis from using pulse signal envelope modulation patterns to using pulse transit time (PTT) and its derivatives. This parameter change eliminates sensitivity to vascular tone variations and movement artifacts while maintaining detection capability for sleep disordered breathing events.
Solution Approach 2:
The patent introduces pulse transit time as an intermediary parameter that mediates between the raw pulse signal and the respiratory modulation analysis. By using PTT as an intermediate measure, the system achieves more precise detection that is not confounded by vascular tone changes or patient movement.
2Difficulty of detecting and measuring
If pulse signal envelope modulation is analyzed to distinguish obstructive and central apnea, then differentiation is attempted, but reliability deteriorates due to confounding factors
Solution Approach 1:
The patent changes the analyzed parameter from pulse envelope modulation to pulse transit time and its relationship with respiratory cycle. This parameter transformation provides more reliable differentiation between obstructive and central apnea by eliminating confounding effects of vascular tone and movement.
Solution Approach 2:
The patent uses feedback from multiple parameters including PTT, respiratory flow, and oxygen saturation to improve the reliability of apnea differentiation. By integrating multiple feedback signals, the system achieves more accurate and reliable distinction between obstructive and central apnea types.
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 provides accurate differentiation between obstructive and central sleep apneas, reducing confounding effects from vascular tone and movement, and offers a quantitative assessment of myocardial contractility and breathing conditions.
Implementation Method 1
monitoring circulatory pulse waveforms recorded from a person's body; determining changes in the effectiveness of the heart's pumping action as reflected by the absolute value of an upstroke index
Implementation Method 2
normalizing said circulatory pulse systolic upstroke waveforms such that the magnitude of the trough to peak amplitude of each such systolic upstroke is set to a predetermined value; determining at least one index of the upstroke to characterize the strength of the contraction of the heart
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
Method and apparatus for the non-invasive detection of certain breathing conditions, certain sleep disordered breathing conditions, or assessment of the person's myocardial contractility and its dynamic changes, comprising steps of: determining the sleep or wake status of a person, monitoring circulatory pulse waveforms and amplitude normalized pulse wave systolic upstrokes recorded from a person's body and determining at least one index of the upstroke to characterize the strength of the contraction of the heart during the systolic upstroke during a series of heart beats relating to a breathing cycle or an absent anticipated breathing cycle of the patient, and determining that a certain change in a breathing condition, a sleep disordered breathing condition, or assessment of the person's myocardial contractility and its dynamic changes, has occurred when a specific change in the sleep disordered breathing analysis, and the at least one index of the upstroke has been detected.