Central Blood Pressure Monitoring via Standard Automatic Arm Cuff
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Solution Overview
Problem
Current automatic arm cuff devices for monitoring central blood pressure suffer from significant errors due to inaccurate brachial blood pressure calibration and the use of one-size-fits-all generalized transfer functions, limiting their clinical utility.
Innovation Solution
A method using a standard automatic arm cuff to measure cuff pressure waveforms, extract features, and compute central blood pressure values through machine learning or physiologic modeling, specifically estimating brachial blood pressure and scaling pulse volume plethysmography waveforms to determine central blood pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If population average methods are used to estimate brachial BP levels in automatic arm cuffs, then device complexity is reduced and ease of operation is improved, but measurement precision of brachial BP levels deteriorates
Solution Approach 1:
The patent changes the parameters used for BP estimation from population averages to individual-specific parameters extracted from the cuff pressure waveform characteristics. By analyzing waveform morphology, oscillation patterns, and pressure-time relationships specific to each patient, the system achieves more accurate brachial BP estimation without requiring complex additional hardware or procedures.
2Ease of manufacture
If a one-size-fits-all generalized transfer function is used to compute central BP from peripheral waveform, then device complexity is reduced and ease of manufacture is improved, but measurement precision of central BP deteriorates
Solution Approach 1:
The patent applies local quality by transitioning from a uniform generalized transfer function to patient-specific transfer functions or calibration factors. Each patient's arterial characteristics, wave reflection patterns, and pulse wave velocity are considered to create individualized transformation models that accurately convert peripheral waveform data to central BP values, accounting for anatomical and physiological variations.
Solution Approach 2:
The system performs preliminary individualized calibration or characterization during the initial measurement phase. By extracting patient-specific waveform features and establishing personalized transfer relationships before computing central BP, the system prepares customized transformation parameters that improve measurement accuracy without adding complexity to the core manufacturing process.
3Device complexity
If standard automatic arm cuff is used instead of special automatic arm cuff, then device complexity is reduced and ease of operation is improved, but the ability to perform additional cuff inflations/deflations is lost
Solution Approach 1:
The patent makes the standard automatic arm cuff universal by demonstrating that a single cuff design can serve multiple functions: traditional brachial BP measurement, central BP derivation through waveform analysis, and individualized calibration. By extracting rich information from the standard cuff pressure waveform and applying advanced signal processing and transfer functions, the system eliminates the need for specialized multi-functional cuffs while maintaining measurement versatility.
Data Source
AI summary
Current oscillometric devices for monitoring central blood pressure (BP) maintain the cuff pressure at a constant level to acquire a pulse volume plethysmography (PVP) waveform and calibrate it to brachial BP levels estimated with population average methods. A physiologic method was developed to further advance central BP measurement. A patient-specific method was applied to estimate brachial BP levels from a cuff pressure waveform obtained during conventional deflation via a nonlinear arterial compliance model. A physiologically-inspired method was then employed to extract the PVP waveform from the same waveform via ensemble averaging and calibrate it to the brachial BP levels. A method based on a wave reflection model was thereafter employed to define a variable transfer function, which was applied to the calibrated waveform to derive central BP.