Cuffless Blood Pressure Monitoring via Pulse Transit Time
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Solution Overview
Problem
Traditional blood pressure measurement systems are discontinuous and invasive, failing to capture the dynamic changes in blood pressure over time, necessitating a non-invasive, cuffless method for continuous monitoring.
Innovation Solution
A system and method utilizing a processor to calculate blood pressure based on pulse transit time, acquired through signals from heart activity and pulse waves, with calibration values specific to the subject, allowing for continuous, non-invasive monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If traditional cuff-based blood pressure measurement is used, then measurement accuracy is maintained, but continuity of monitoring is lost due to intermittent measurements
Solution Approach 1:
The patent replaces the mechanical cuff-based measurement system with an optical sensing system. The device uses photoplethysmography (PPG) sensors to detect pulse wave characteristics and electrocardiogram (ECG) sensors to detect heart electrical activity, eliminating the need for mechanical inflation and deflation of cuffs. This substitution enables continuous monitoring while maintaining measurement accuracy through optical and electrical signal detection.
Solution Approach 2:
The patent introduces pulse transit time (PTT) as an intermediary parameter to indirectly measure blood pressure. Instead of directly measuring blood pressure through mechanical means, the system measures the time it takes for a pulse wave to travel between two points on the body, and uses this PTT value along with calibration data to calculate blood pressure. This intermediary approach enables continuous non-invasive monitoring.
2Productivity
If continuous blood pressure monitoring is implemented, then dynamic blood pressure changes are captured, but measurement invasiveness increases
Solution Approach 1:
The patent replaces invasive mechanical cuff inflation with non-invasive optical sensing. The PPG sensors use light to detect blood volume changes in the tissue, and ECG sensors detect electrical heart activity through skin contact. These optical and electrical measurement methods are completely non-invasive, allowing continuous monitoring without the harmful effects of repeated mechanical cuff inflation.
Solution Approach 2:
The patent uses optical copies (light absorption and reflection patterns) of blood flow characteristics to infer blood pressure information. The PPG sensor captures the optical signature of pulsating blood vessels, creating an optical copy of the hemodynamic state that can be continuously analyzed without physical intrusion into the cardiovascular system.
3Ease of operation
If cuffless blood pressure monitoring is used, then patient comfort is improved, but measurement accuracy deteriorates
Solution Approach 1:
The patent uses pulse transit time (PTT) and calibration values as intermediaries to bridge the gap between comfortable non-invasive measurement and accurate blood pressure determination. The system measures easily obtainable PTT from optical and electrical signals, then uses pre-established calibration relationships (determined during initial setup or through machine learning models) to accurately calculate blood pressure from these comfortable-to-obtain measurements.
Solution Approach 2:
The system incorporates feedback mechanisms where initial blood pressure measurements (possibly from traditional cuff methods) are used to calibrate the optical sensing system. This calibration feedback loop adjusts the relationship between PTT and blood pressure for each individual patient, ensuring high accuracy while maintaining the comfort of continuous cuffless monitoring. The system continuously refines its measurements based on ongoing physiological data.
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 accurate, continuous blood pressure monitoring without the need for invasive cuffs, providing insights into transient changes in blood pressure and improving hypertension management and cardiovascular risk prediction.
Implementation Method 1
A pulse transit time based on a difference between the first feature and the second feature may be computed
Data Source
AI summary
The present disclosure relates to a device, method and system for calculating, estimating, or monitoring the blood pressure of a subject. At least one processor, when executing instructions, may perform one or more of the following operations. A first signal representing heart activity of the subject may be received. A second signal representing time-varying information on at least one pulse wave of the subject may be received. A first feature in the first signal may be identified. A second feature in the second signal may be identified. A pulse transit time based on a difference between the first feature and the second feature may be computed. The blood pressure of the subject may be calculated according to a first model based on the computed pulse transit time and a first set of calibration values, the first set of calibration values relating to the subject.