Hepatic Encephalopathy Grading System Using Objective Clinical Criteria

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Solution Overview

Problem

Current grading systems for hepatic encephalopathy (HE) episodes are subjective and prone to variability, making prompt and accurate identification and classification challenging, which can delay appropriate therapeutic interventions.

Innovation Solution

A novel grading system that classifies HE episodes based on specific criteria such as disorientation, lethargy, asterixis, and coma, requiring only one of these criteria to be met for classification, with a focus on precise operational definitions and timeframes to reduce subjectivity and variability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional subjective grading systems are used for HE episodes, then clinical flexibility is maintained, but measurement precision and reliability deteriorate due to variability and subjectivity

Engineering Contradiction:
Improvegrading accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the grading system by changing the parameters from subjective clinical judgment to objective measurable criteria. Specific parameters such as disorientation (assessed through orientation questions), lethargy (assessed through consciousness level), asterixis (assessed through motor control tests), and coma (assessed through responsiveness) are defined with clear operational definitions and timeframes. This parameter transformation enables precise measurement while maintaining systematic complexity through structured assessment protocols.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If subjective grading criteria are used, then ease of operation is maintained, but reliability deteriorates due to inter-observer variability

Engineering Contradiction:
Improvegrading consistencyVSAvoidassessment simplicity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The grading system is segmented into distinct, independently assessable criteria: disorientation (cognitive function), lethargy (consciousness level), asterixis (motor control), and coma (responsiveness). Each criterion is further segmented into specific observable indicators with defined timeframes (e.g., disorientation lasting at least one hour). This segmentation allows different observers to assess the same patient using identical breakdown components, improving reliability while maintaining operational simplicity through modular assessment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system incorporates feedback mechanisms through standardized assessment protocols that provide clear guidance on what constitutes each grade level. The operational definitions serve as feedback criteria that enable observers to self-correct and align their assessments with established standards. This feedback loop reduces inter-observer variability by providing continuous reference points for accurate grading.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If detailed subjective assessments are performed, then measurement precision improves, but loss of time increases due to prolonged evaluation

Engineering Contradiction:
Improvediagnostic accuracyVSAvoidassessment duration
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The assessment protocol employs preliminary action by establishing a hierarchical evaluation structure where broader criteria are assessed first. The system is designed to identify the highest grade level present through a sequence of predetermined questions and observations. If clear indicators of severe HE (such as coma or profound disorientation) are detected early in the assessment, the evaluation can be concluded more quickly without requiring exhaustive assessment of all criteria, thus reducing time loss while maintaining diagnostic accuracy.

Inventive Principle:
Principle #10Preliminary action

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

The system provides a simpler, more objective method for identifying and grading HE episodes, leading to more rapid and precise treatment by reducing variability and subjectivity in clinical assessments.

Implementation Method 1

The therapeutic intervention is administered at a dosage sufficient to maintain the subject's fasting blood ammonia level at or below a specified threshold of 1.5 times the upper limit of normal

Methodology Applied
Scientific EffectAmmonia binding: Absorption (physical)

Data Source

PatentEP3019074B1Diagnosing, grading, monitoring, and treating hepatic encephalopathy
Publication Date: 2018.08.29 HORIZON THERAPEUTICS LLC

AI summary

The present disclosure provides methods, systems, and instruments for the determination by a physician or medical professional whether a subject is experiencing or has recently experienced an overt HE episode and for grading overt HE episodes as well as methods, systems, instruments and tools for screening for overt HE episodes by a non-medical professional such as a caregiver. Also provided are methods of treating HE episodes and methods of monitoring HE episode treatment that incorporate these methods, systems, instruments, and tools.