Non-invasive ICP Estimation via Arterial Waveform Analysis

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Solution Overview

Problem

Current methods for measuring intra-cranial pressure (ICP) are invasive, carrying risks of cerebral damage, hemorrhage, and infection, and lack non-invasive alternatives, especially for unconscious patients or those with closed head trauma, stroke, or brain surgery, where timely and accurate ICP estimation is crucial.

Innovation Solution

A non-invasive method estimates ICP by analyzing patterns of arterial pressure and flow waves in arteries supplying blood to the brain, using measurements from peripheral arteries and applying transfer functions to derive central arterial waveforms, identifying features like pressure and flow augmentation indexes to compare with gender-specific data for ICP estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If invasive methods (catheter insertion, lumbar puncture, micromanometer insertion) are used to measure ICP, then measurement precision is improved, but object-affected harmful factors worsen due to risks of cerebral damage, hemorrhage, and infection

Engineering Contradiction:

ImproveICP measurement accuracyVSAvoidcerebral damage, hemorrhage, infection

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent uses an intermediary substance (contrast medium) introduced into the arterial system to enable non-invasive measurement of ICP. The contrast medium modifies the arterial pressure waveform in a way that allows derivation of ICP information through external monitoring, thus mediating between the arterial system and the measurement device without requiring direct brain penetration

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical invasive measurement system (physical catheters and needles penetrating the brain) with a non-invasive optical or electromagnetic monitoring system that detects arterial pressure waveform characteristics externally. This substitution eliminates the need for physical penetration of the cranial vault while preserving measurement capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If invasive ICP monitoring is performed, then reliability of ICP data is improved, but device complexity and procedural risk increase

Engineering Contradiction:

ImproveICP monitoring reliabilityVSAvoidprocedural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent enables the arterial system itself to provide the measurement information needed for ICP assessment. By analyzing the natural arterial pressure waveform (modified by contrast medium) that already exists in the system, the method eliminates the need for separate invasive sensing devices within the brain, allowing the body's own circulatory system to serve the measurement function

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If non-invasive methods are used to estimate ICP, then object-affected harmful factors are reduced, but measurement precision deteriorates due to inability to accurately capture central arterial waveforms

Engineering Contradiction:

Improveprocedural riskVSAvoidICP estimation accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent changes the physical parameters of the arterial system by introducing a contrast medium that alters the arterial pressure waveform characteristics. This parameter change (modification of wave reflection properties) enables the extraction of ICP-related information from the modified waveform, achieving measurement precision that would otherwise require invasive access

Inventive Principle:

Principle #35Parameter changes

4Ease of operation

If peripheral arterial pressure measurements are used to estimate central pressure, then ease of operation is improved, but measurement precision worsens due to wave reflection effects

Engineering Contradiction:

Improvemeasurement accessibilityVSAvoidcentral pressure estimation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent modifies the arterial waveform parameters through contrast medium administration, which changes wave reflection characteristics. This parameter change allows the peripheral waveform to more accurately reflect central pressure conditions, bridging the gap between easy peripheral access and accurate central pressure estimation

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11744477B2Non-invasive method of estimating intra-cranial pressure (ICP)

Publication Date: 2023.09.05 OROURKE MICHAEL F

AI summary

A non-invasive method of estimating intra-cranial pressure (ICP). The method including the steps of: a. non-invasively measuring pressure pulses in an upper body artery; b. determining central aortic pressure (CAP) pulses that correspond to these measured pressure pulses; c. identifying features of the ICP wave which denote cardiac ejection and wave reflection from the cranium, including Ejection Duration (ED) and Augmentation Index of Pressure (PAIx); d. non-invasively measuring flow pulses in a central artery which supplies blood to the brain within the cranium; e. identifying features of the measured cerebral flow waves which denote cardiac ejection and wave reflection from the cranium as Flow Augmentation Index (FAIx); f. calculating an ICP flow augmentation index from the measured central flow pulses; g. comparing the calculated ICP pressure augmentation index (PAIx) and flow augmentation index (FAIx) to measure (gender-specific) pressure and flow augmentation data indicative of a measured ICP to thereby estimate actual ICP; and h. noting any disparity between ED measured for pressure waves and ED measured for flow.