Oscillometric Blood Pressure Model Using Waveform Mechanics
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Solution Overview
Problem
Existing non-invasive blood pressure measurement methods, such as oscillometry, are often inaccurate due to their empirical nature and reliance on fixed ratios, while more accurate methods like finger-cuff photoplethysmography are expensive and inconvenient.
Innovation Solution
A method using physical models to represent the oscillometric cuff pressure waveform, allowing for the estimation of blood pressure by determining model parameters from the waveform and a priori measurements, thereby providing a subject-specific and more accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If oscillometric method with fixed-ratio is used, then automated measurement is achieved, but measurement precision deteriorates due to empirical nature and inability to account for individual arterial characteristics
Solution Approach 1:
The patent transforms the fixed-ratio empirical parameters into variable parameters that are dynamically determined from the oscillometric waveform characteristics. The system extracts multiple features from the waveform (amplitude, frequency, shape parameters) and uses them to calculate individualized blood pressure values, allowing the measurement parameters to adapt to each patient's specific arterial properties while maintaining automated operation
Solution Approach 2:
The system implements feedback by using the measured oscillometric waveform to continuously refine the blood pressure calculation. The waveform features are fed back into the calculation algorithm to adjust the estimated blood pressure values, creating a closed-loop system that accounts for individual variations in arterial compliance and stiffness without requiring manual intervention
2Measurement precision
If finger-cuff photoplethysmography with arterial unloading principle is used, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent creates a simplified computational model that replicates the physiological relationships underlying the arterial unloading principle without requiring the complex hardware of finger-cuff photoplethysmography. By using a mathematical model of arterial compliance and oscillometric waveform characteristics, the system copies the essential physics of the more complex method while using only standard oscillometric equipment
Solution Approach 2:
The patent replaces the mechanical and optical complexity of finger-cuff photoplethysmography with a computational approach based on standard oscillometric measurements. Instead of using photodetectors and complex mechanical unloading mechanisms, the system uses signal processing and mathematical modeling to achieve similar measurement precision with simpler, more widely available equipment
Data Source
AI summary
A method is provided for determining blood pressure for a subject using a sphygmomanometer. The method includes: measuring an oscillometric cuff pressure waveform of the subject using the sphygmomanometer; representing the measured waveform with a physical model accounting for mechanics of the cuff, an artery and coupling between the cuff and the artery; determining the model unknowns from the measured waveform; and determining blood pressure for the subject using the determined model.