Time-Domain Pulse Wave Analysis for Blood Volume Detection
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Solution Overview
Problem
Existing blood pressure monitoring systems based on amplitude analysis are uncomfortable for users and require frequent recalibration, while time-domain analysis methods struggle to reliably measure small changes in blood pressure, particularly systolic and diastolic variations, due to complexities in arterial pulse propagation and shape changes.
Innovation Solution
A single-site, time-dependent pulse wave analysis system using a physiological model to determine blood pressure by tracking the time evolution of arterial pulse components, specifically measuring the time difference between the primary left ventricular ejection pulse and the iliac reflection to assess blood volume changes, which is less dependent on coupling pressure and resistant to signal disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amplitude-dependent blood pressure monitoring is used, then blood pressure can be measured, but user comfort deteriorates and frequent recalibration is required
Solution Approach 1:
The patent replaces the mechanical amplitude-dependent measurement system with a time-domain analysis system that measures pulse wave propagation time. This substitution eliminates the need for mechanical cuff inflation and pressure tracking, thereby improving user comfort while maintaining measurement capability through temporal rather than amplitude-based detection
Solution Approach 2:
The patent changes the measurement parameter from amplitude (pressure force) to time (pulse transit time). By measuring the time delay between the ECG QRS complex and the corresponding pulse wave at the arterial site, the system achieves blood pressure determination without requiring mechanical coupling or frequent recalibration, thus resolving the contradiction between measurement accuracy and user comfort
2Reliability
If two-site pulse transit time measurement is used, then blood pressure tracking is possible, but measurement precision for small changes deteriorates
Solution Approach 1:
The patent segments the arterial pulse wave into distinct components (forward wave and reflected wave) and analyzes their temporal characteristics separately. By identifying specific features within the pulse waveform and measuring their time delays relative to the ECG signal, the system achieves higher precision in detecting small blood pressure changes compared to crude two-site transit time measurements
Solution Approach 2:
The patent performs preliminary identification and characterization of pulse wave components before making measurements. By establishing the temporal relationship between ECG events and specific pulse wave features in advance, and by preprocessing the signal to identify key landmarks, the system improves the precision of small blood pressure change detection through prepared reference frameworks
3Measurement precision
If traditional cuff-based blood pressure monitoring is used, then blood pressure can be measured, but user comfort and continuity of monitoring deteriorate
Solution Approach 1:
The patent implements continuous blood pressure monitoring by continuously analyzing the temporal relationship between ECG signals and arterial pulse waves. Unlike intermittent cuff-based measurements, this system provides uninterrupted measurement capability by continuously tracking pulse transit time from the heart to the peripheral arterial site, enabling sustained monitoring without breaking the measurement action
Solution Approach 2:
The patent replaces the mechanical cuff inflation system with a physiological signal-based measurement system that uses electrical (ECG) and mechanical (pulse wave) signals. This substitution eliminates the need for repeated mechanical intervention, allowing continuous monitoring to proceed without the discomfort and interruption inherent in traditional cuff-based methods
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
This approach allows for non-invasive, continuous monitoring of systolic, diastolic, and mean blood pressure with increased user comfort, reduced need for recalibration, and accurate detection of small blood pressure variations and changes in blood volume, such as dehydration or hemorrhaging, without the discomfort of traditional cuff-based methods.
Implementation Method 1
the propagation velocity of the arterial pulse is highly dependent on the arterial pressure
Implementation Method 2
the propagation velocity of the arterial pulse is highly dependent on the arterial pressure
Implementation Method 3
they have to couple to the pressure wave within the artery
Implementation Method 4
reflected pulses readily propagate through the arterial system, and the pulse measured at a certain arterial site is actually a superposition of a number of different and distinct pulse components
Data Source
AI summary
A system for detecting dehydration, hemorrhaging, and increases in blood volume comprising monitors the time difference between the arrival of the primary left ventricular ejection pulse (pulse T1) and the arrival of the iliac reflection (pulse T3) to determine an arterial pulse parameter which is the time difference between T1 T3. Changes in T3 minus T1 are indicative of something happening to blood volume. If the T1-3 value goes up and the patient is on an infusion system, it can be an indication of having too much fluid pumped and if T1-3 is lower than it should be for an individual, they are either dehydrated (which can result in decreases in blood volume), they are hemorrhaging, or they have hemorrhaged. A downtrend in T13 can tell whether someone is continuing to hemorrhage.