Sub-Epidermal Moisture Measurement for Early Pressure Injury Detection
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Solution Overview
Problem
Current methods for detecting pressure injuries or ulcers are ineffective in early detection due to reliance on subjective clinical judgment and visual assessments, which have low sensitivity and specificity, especially in darkly pigmented skin, and fail to detect non-visible sub-epidermal injuries in a timely manner.
Innovation Solution
A method involving the measurement of spatial variation in Sub-Epidermal Moisture (SEM) values at multiple locations within defined tissue assessment areas, calculating averages, and flagging tissue damage based on a predetermined cut-off threshold, using a system capable of making SEM measurements and biocapacitance assessments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If subjective clinical judgment and visual assessments are used to detect pressure injuries, then the method is simple and inexpensive, but the sensitivity and specificity are low and early detection is delayed
Solution Approach 1:
The patent replaces subjective mechanical visual assessment with an objective electronic measurement system that quantifies sub-epidermal moisture levels. The SEM measurement device uses electrical impedance spectroscopy to detect moisture changes in the sub-epidermal layer, providing numerical data instead of subjective visual judgment. This substitution dramatically improves detection sensitivity and specificity while maintaining clinical usability through automated threshold comparison.
2Loss of time
If visual and palpation tests are used for skin assessment, then the equipment requirement is minimal, but the diagnostic latency is extended and early microscopic damage cannot be detected
Solution Approach 1:
The patent performs preliminary detection of sub-epidermal moisture changes before visible skin damage occurs. By measuring SEM levels continuously or at regular intervals, the system identifies microscopic tissue damage in its early stages, allowing intervention before the injury progresses to visible ulceration. This preliminary action reduces diagnostic latency from days or weeks to hours or minutes.
Solution Approach 2:
The patent uses sub-epidermal moisture level as an intermediary marker to detect early tissue damage. Instead of directly observing visible skin changes, the system measures moisture accumulation in the sub-epidermal layer, which serves as an early warning signal of underlying tissue compromise. This intermediary measurement enables detection of damage before it becomes visually apparent.
3Reliability
If standard risk assessment tools and visual skin assessment are used, then the assessment process is quick and requires no special equipment, but the sensitivity approaches randomness and early intervention is impossible
Solution Approach 1:
The patent enables the assessment system to self-evaluate by automatically comparing measured SEM values against predetermined thresholds. The device performs its own diagnostic function by processing the measurement data and generating alerts when damage is detected, reducing reliance on subjective clinician interpretation. This self-service capability maintains high diagnostic reliability while improving assessment efficiency through automated decision-making.
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
This approach significantly improves the sensitivity and specificity of detecting pressure ulcers by identifying damaged tissue through objective means, enabling earlier intervention and reducing diagnostic latency across various skin types.
Implementation Method 1
obtaining a first plurality of SEM measurements at a first plurality of locations within a first tissue assessment area, obtaining a second plurality of SEM measurements at a second plurality of locations within a second tissue assessment area
Data Source
AI summary
The present disclosure provides methods for evaluating tissue damage and the use of spatial variation in Sub-Epidermal Moisture (SEM) values to determine damaged tissue for clinical intervention. The present disclosure provides methods of identifying deep and early-stage pressure-induced injuries or ulcers (PI/PU). The present disclosure provides algorithm for computing SEM delta values which inform clinical decision-making for developing intact skin PI/PUs including suspected deep tissue injury (sDTI) and Stage I PI/PUs.