Non-Invasive Hemodynamic Analysis via Pulse Wave

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Solution Overview

Problem

Current methods for monitoring hemodynamic parameters in patients during and after surgery are invasive, causing significant burden and unable to distinguish between decreased cardiac contractile function and reduced blood circulation, necessitating a non-invasive solution for accurate analysis.

Innovation Solution

A hemodynamic parameter analysis apparatus and program that non-invasively acquire and analyze central venous pressure and cardiac output using physiological information such as pulse waves and electrocardiograms, displaying results on a coordinate plane to differentiate between congestion and circulatory failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If invasive measurement methods (Swan-Ganz catheter) are used to obtain pulmonary capillary wedge pressure and cardiac output, then measurement precision is improved, but patient burden increases

Engineering Contradiction:
Improvehemodynamic parameter measurement precisionVSAvoidpatient burden
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical invasive measurement system (Swan-Ganz catheter insertion into pulmonary artery) with a non-invasive optical measurement system using photoplethysmogram sensors on the body surface. This substitution eliminates the harmful mechanical intrusion while preserving the ability to measure hemodynamic parameters through optical detection of blood volume changes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces photoplethysmogram signals as an intermediary medium to indirectly obtain hemodynamic information. Instead of directly measuring pressure and flow inside the vessel, the system uses optical absorption changes in peripheral blood vessels as a mediator to infer cardiac output and other hemodynamic parameters through mathematical modeling.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If only cardiac output is measured, then measurement simplicity is improved, but diagnostic accuracy deteriorates because it cannot distinguish between contractile function decrease and circulating blood decrease

Engineering Contradiction:
Improvemeasurement simplicityVSAvoiddiagnostic accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the single cardiac output measurement into multiple independent hemodynamic parameters including stroke volume, heart rate, and peripheral vascular resistance. By dividing the overall cardiac function assessment into these component parameters, the system can identify which specific aspect (contractile function vs. circulating blood volume) is abnormal, thereby improving diagnostic accuracy while maintaining operational simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a one-dimensional cardiac output measurement to a multi-dimensional hemodynamic parameter space. By adding temporal dynamics (pulse wave velocity, augmentation index) and vascular resistance dimensions to the basic flow measurement, the system creates a comprehensive parameter set that enables differentiation between various pathological states without complicating the measurement process.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 reduced patient burden during measurement while accurately distinguishing between cardiac function and blood circulation issues, facilitating appropriate treatment strategies.

Implementation Method 1

a signal acquired by a sensor that is in contact with or close to a body surface of a subject

Methodology Applied
Scientific EffectPulse wave detection:

Implementation Method 2

pulse wave transit time obtained based on a pulse wave

Methodology Applied
Scientific EffectPulse wave transit time measurement:

Data Source

PatentEP3925526A1Hemodynamic parameter analysis apparatus and hemodynamic parameter analysis program
Publication Date: 2021.12.22 NIHON KOHDEN CORP
  • EP3925526A1 patent drawingFigure 1
  • EP3925526A1 patent drawingFigure 2~3
  • EP3925526A1 patent drawingFigure 4~5

AI summary

A hemodynamic parameter analysis apparatus includes an acquisition unit and a hemodynamic parameter analysis unit. The acquisition unit configured to acquire venous pressure and cardiac output that are calculated based on physiological information of a subject. The hemodynamic parameter analysis unit configured to analyze hemodynamic parameters of the subject based on the venous pressure and the cardiac output that are acquired by the acquisition unit.