Nonlinear Arterial Compliance Model for Blood Pressure
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Solution Overview
Problem
Current models fail to accurately determine aortic compliance parameters and blood pressure from pulse wave velocity (PWV) measurements, lacking predictive mechanisms that incorporate peak pressure, ejection time, and modulus of elasticity, and are limited by linear assumptions that contradict experimental data.
Innovation Solution
A nonlinear one-dimensional mathematical model for blood pressure wave propagation in compliant arteries, which accounts for pressure-dependent pulse wave velocity and incorporates measurements of flow velocity, arterial compliance, and blood pressure to calculate aortic compliance and distensibility, allowing for continuous monitoring of physiological parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If linear models are used to predict PWV as a function of geometric and physical properties, then the model simplicity is maintained, but the measurement precision and accuracy deteriorate because these models contradict empirical evidence that PWV is correlated to pressure and ejection time
Solution Approach 1:
The patent transforms the classical Moens-Korteweg model by introducing pressure-dependent parameters. The elastic modulus E is modified to E(p) = E0 * exp(αp), where p is pressure and α is a compliance parameter. This parameter change allows the model to capture the nonlinear relationship between pressure and pulse wave velocity, resolving the contradiction between model simplicity and measurement accuracy.
2Measurement precision
If pressure-dependent elastic modulus is introduced to the Moens-Korteweg model, then the measurement precision improves by incorporating empirical evidence, but the device complexity increases due to the nonlinear model requirements
Solution Approach 1:
The patent introduces a pressure-dependent elastic modulus E(p) = E0 * exp(αp) that incorporates empirical evidence about PWV correlation with pressure. This single parameter modification (adding compliance parameter α) captures the nonlinear physics without requiring complex computational frameworks, thus improving measurement precision while controlling model complexity.
3Ease of operation
If classical Moens-Korteweg model is used for non-invasive blood pressure measurement, then the ease of operation is maintained, but the reliability deteriorates because the model assumes pressure-independent wave speed which contradicts experimental data
Solution Approach 1:
The patent modifies the classical Moens-Korteweg model by making the elastic modulus pressure-dependent: E(p) = E0 * exp(αp). This allows the model to reflect experimental observations that pulse wave velocity increases with pressure, thereby improving the reliability of non-invasive blood pressure measurements while maintaining the operational simplicity of usingPWV as the primary measurement.
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 non-invasive determination of blood pressure and arterial compliance by using PWV measurements, providing a physics-based approach that corrects classical Moens-Korteweg models and accounts for nonlinearities, offering a more accurate assessment of vascular health and risk stratification for cardiovascular diseases.
Implementation Method 1
The non-invasive and continuous measurement of blood pressure has been attempted using empirically derived models based on the Moens-Korteweg (M-K) speed of propagation. According to linearized acoustics model, the M-K speed of propagation is a constant, dependent on Young's modulus, wall thickness, radius, and blood density.
Implementation Method 2
Since the M-K speed is pressure independent, which contradicts to the experimental data, some authors integrate pressure into the acoustics M-K expression assuming that elastic modulus is an exponential function of pressure.
Data Source
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AI summary
Disclosed are methods for determining physiological parameters of an individual including blood pressure, arterial compliance, flow velocity, and pressure wave velocity. A noninvasive method for determining the blood pressure of a patient is based on measurements of flow velocity, pulse wave velocity and arterial compliance. A noninvasive method for determining the arterial compliance of a patient is based on measurements of blood pressure, flow velocity, and pulse wave velocity.