Plethysmograph Variability Index With Passive Leg Raising

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Accurate prediction of fluid responsiveness or unresponsiveness in patients is difficult and unreliable, making it challenging to determine whether fluid administration will increase stroke volume or cardiac output, which is crucial for effective hydration management.

Innovation Solution

A system using a plethysmograph variability parameter, such as the Pleth Variability Index (PVI), in conjunction with a passive leg raising (PLR) test, to predict fluid responsiveness by analyzing plethysmograph waveforms and physiological data from non-invasive sensors, enabling informed decisions on fluid administration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional methods are used to predict fluid responsiveness, then the assessment can be performed, but the prediction accuracy is difficult and unreliable

Engineering Contradiction:

Improveprediction accuracyVSAvoidreliability of fluid responsiveness prediction

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent transforms the prediction approach by changing from static parameters (single time-point measurements) to dynamic parameters (temporal variations in plethysmograph waveform). The PVI calculates respiratory-induced variations in perfusion index over time, capturing the dynamic response to mechanical ventilation, which provides more reliable information about fluid responsiveness than traditional static measurements.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces invasive mechanical assessment methods (such as fluid challenges requiring actual fluid administration or echocardiographic imaging) with a non-invasive optical system. The pulse oximetry device uses light absorption principles to detect plethysmograph waveform variations, substituting complex mechanical or imaging systems with a simple optical sensor that continuously monitors peripheral blood flow dynamics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If invasive methods are used to assess fluid responsiveness, then accurate measurements can be obtained, but the procedure becomes more complex and carries higher risk

Engineering Contradiction:

Improvefluid responsiveness measurement accuracyVSAvoidcomplexity of assessment procedure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces invasive mechanical assessment methods with a non-invasive optical system. The pulse oximetry device uses light absorption principles to detect plethysmograph waveform variations, substituting complex mechanical or imaging systems with a simple optical sensor that continuously monitors peripheral blood flow dynamics without requiring patient intervention or specialized training.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system utilizes the patient's own physiological response to mechanical ventilation as the test stimulus. The respiratory-induced variations in plethysmograph waveform occur naturally during normal mechanical ventilation, eliminating the need for external fluid challenges or active patient participation. The patient's circulatory system serves as its own test subject, responding passively to the rhythmic compression and relaxation of vessels during breathing cycles.

Inventive Principle:

Principle #25Self-service

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, non-invasive, and continuous assessment of patient hydration status and fluid responsiveness, guiding fluid administration to improve hemodynamic function and prevent fluid overload.

Implementation Method 1

The non-invasive physiological sensor can be configured to emit light towards a tissue site of a patient, detect the light after it has interacted with the tissue site, and generate the sensor signal based at least in part on the detected light

Methodology Applied

Scientific EffectLight absorption and detection: Absorption (EM radiation)

Implementation Method 2

demodulating the sensor signal to generate a plethysmograph waveform including a plurality of pulses corresponding to pulsatile blood flow within the tissue site

Methodology Applied

Scientific EffectPlethysmography:

Data Source

PatentUS12484844B2System to monitor and manage patient hydration via plethysmograph variability index in response to the passive leg raising

Publication Date: 2025.12.02 MASIMO CORP

AI summary

Techniques for predicting fluid responsiveness or fluid unresponsiveness are described. A processor can determine a first prediction of fluid responsiveness or unresponsiveness based on a plethysmograph variability parameter associated with a plethysmograph waveform, and can determine a second prediction of fluid responsiveness or unresponsiveness based on a fluid responsiveness parameter that is associated with an elevation of one or more limbs of the patient. The processor can determine an overall prediction of fluid responsiveness or unresponsiveness based on the first and/or second predictions. Based on overall prediction, the processor can cause administration of fluids and/or termination of administration of fluids.