Blood Pressure Calibration via Pulse Wave Velocity
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Solution Overview
Problem
Cuff-based methods for measuring blood pressure are discontinuous, disturbing patients and missing inter-measurement BP fluctuations, and existing continuous methods require calibration that may disrupt patients, especially during sleep.
Innovation Solution
A body-worn vital sign monitor system using pulse pressure wave data, combining optical and electrical sensors to measure time-dependent waveforms, with a pneumatic cuff for calibration, processes these signals to calculate continuous non-invasive blood pressure, accounting for patient-specific properties like arterial compliance, and adjusts for motion and posture to prevent false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cuff-based methods are used for blood pressure measurement, then measurement accuracy is improved, but patient disturbance and discontinuous monitoring occur
Solution Approach 1:
The patent replaces the mechanical cuff-based measurement system with an optical sensing system that uses photoplethysmography (PPG) to detect blood pressure changes through light transmission through tissue, eliminating the need for physical inflation and deflation of cuffs that disturb patients
Solution Approach 2:
The patent implements continuous blood pressure monitoring by continuously measuring pulse wave characteristics and processing them through algorithms that track blood pressure changes over time, eliminating the discontinuous nature of traditional cuff-based measurements
2Measurement precision
If cuff-based methods are used for blood pressure measurement, then measurement accuracy is improved, but inter-measurement BP fluctuations are missed
Solution Approach 1:
The patent enables continuous blood pressure monitoring by continuously capturing pulse waveforms and processing them to track blood pressure changes between traditional measurement intervals, preventing loss of information about BP fluctuations
Solution Approach 2:
The patent uses feedback algorithms that continuously process pulse wave data and adjust blood pressure estimates based on real-time changes in pulse characteristics, allowing the system to detect and report inter-measurement fluctuations
3Measurement precision
If calibration is performed using conventional blood pressure cuff, then measurement accuracy is improved, but patient disturbance during sleep occurs
Solution Approach 1:
The patent replaces mechanical cuff inflation for calibration with optical sensing that detects blood pressure changes through light transmission, allowing calibration to occur during sleep without mechanical disturbance to the patient
Solution Approach 2:
The patent enables the system to perform self-calibration by automatically detecting and processing pulse wave characteristics to establish baseline values without requiring external cuff-based measurement intervention during sleep
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 continuous, non-invasive, and accurate blood pressure monitoring, reducing patient disturbance and false alarms by using a combination of sensors to process pulse pressure wave data and account for patient-specific factors, providing reliable blood pressure readings and alerts for decompensation.
Implementation Method 1
SpO2 is typically measured using a sensor that attaches to a patient's finger, and includes optical systems operating in both the red and infrared spectral regions. A photodetector measures radiation emitted from the optical systems that transmits through the patient's finger
Implementation Method 2
multiple electrodes typically attach to a patient's chest to determine a time-dependent ECG component characterized by a sharp spike called the 'QRS complex'. The QRS complex indicates an initial depolarization of ventricles within the heart
Implementation Method 3
A first aspect relates to a body-worn vital sign monitoring system. The system includes a first sensor that generates a first time-dependent waveform indicative of one or more contractile properties of the patient's heart
Data Source
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AI summary
The invention provides a system and method for measuring vital signs (e.g. SYS, DIA, SpO2, heart rate, and respiratory rate) and motion (e.g. activity level, posture, degree of motion, and arm height) from a patient. The system features: first and second sensors configured to independently generate time-dependent waveforms indicative of one or more contractile properties of the patient' s heart; and a cuff-based oscillometric module. A processing component, typically worn on the patient's body and featuring a microprocessor, receives the time-dependent waveforms generated by the different sensors and processes them to determine patient- specific calibration values for use in a continuous blood pressure measurement based on pulse wave velocity (PWV).