Photoacoustic Hemodynamic Monitoring via Indicator Dilution
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Solution Overview
Problem
Current physiological monitoring systems lack effective methods for accurately determining hemodynamic parameters such as cardiac output, intrathoracic blood volume, and extravascular lung water using non-invasive and efficient techniques.
Innovation Solution
A physiological monitoring system employing photoacoustic analysis and indicator dilution methods, which involves using a light source to provide a photonic signal to a blood vessel and detecting acoustic pressure signals caused by indicator absorption, allowing for the determination of hemodynamic parameters like cardiac output and extravascular lung water through the analysis of dilution curves and photoacoustic signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive procedures are used to measure hemodynamic parameters, then measurement precision is improved, but device complexity and patient risk increase
Solution Approach 1:
The patent replaces invasive mechanical measurement systems with a non-invasive photoacoustic detection system. The system uses optical energy absorption by blood constituents to generate acoustic signals that can be detected externally, eliminating the need for invasive catheters or surgical procedures while maintaining measurement capability for hemodynamic parameters
Solution Approach 2:
The patent introduces photoacoustic signals as an intermediary mechanism to bridge the gap between internal physiological processes and external measurement. The acoustic signals serve as mediators that carry information about hemodynamic parameters from the blood vessels to external detectors without requiring direct physical intrusion into the cardiovascular system
2Device complexity
If non-invasive techniques are used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent utilizes parameter changes in the photoacoustic signal characteristics (amplitude, frequency, timing) that occur in response to indicator dilution events. By monitoring these dynamic parameter changes as indicators pass through the bloodstream, the system extracts precise hemodynamic information without invasive procedures
Solution Approach 2:
The patent applies photoacoustic detection to specific local regions (blood vessels) with targeted indicator injection, allowing precise measurement of local hemodynamic parameters. The system focuses optical and acoustic energy on specific vascular regions to obtain localized measurement data with high precision
3Measurement precision
If multiple indicators are used for comprehensive hemodynamic assessment, then measurement precision is improved, but loss of substance increases
Solution Approach 1:
The patent employs indicators with multi-functional properties that allow a single indicator to provide multiple measurement capabilities. The indicators are designed to simultaneously enable photoacoustic detection, dilution curve analysis, and various hemodynamic parameter calculations, reducing the need for multiple different indicator substances
Solution Approach 2:
The patent combines multiple measurement functions into a unified indicator system. By merging the properties of different indicator types into a single composite indicator formulation, the system achieves comprehensive hemodynamic assessment while minimizing total indicator consumption through consolidated measurement approaches
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 non-invasive and accurate measurement of hemodynamic parameters by utilizing photoacoustic signals and indicator dilution techniques, providing reliable data for cardiac output, intrathoracic blood volume, and extravascular lung water without the need for invasive procedures.
Implementation Method 1
an acoustic detector that detects an acoustic pressure signal from the first blood vessel site, caused by the absorption of at least some of the photonic signal by one or more constituents at the first blood vessel site
Implementation Method 2
an isotonic indicator and a hypertonic indicator may be provided to the subject at a second blood vessel site
Data Source
AI summary
A patient monitoring system may provide photoacoustic sensing based on an indicator dilution to determine one or more physiological parameters of a subject. The system may detect an acoustic pressure signal, which may include one or more thermo-dilution responses, one or more hemo-dilution responses, or a combination thereof. For example, a thermo-dilution indicator and/or a hemo-dilution indicator may be used to determine one or more hemodynamic parameters. In a further example, an isotonic indicator and a hypertonic indicator may be used to determine one or more hemodynamic parameters of the subject.