Sub-Epidermal Moisture and the Role of Inflammation in Pressure Injury/Ulcer Development
Pressure injuries (PI) (also known as pressure ulcers), are a major health care problem occurring across all healthcare settings1.
These injuries have a significant humanitarian and economic impact2,3,4, but are largely considered to be a preventable5 ‘Never Event’6. In clinical practice, the main emphasis is focussed towards identifying persons at risk of pressure injury development, and then implementing timely preventative interventions. International expert guidelines for PI prevention recommend patient assessment on admission, and daily thereafter7.
In this respect, numerical risk assessment tools (RAT) and a visual skin inspection by the clinician, to assess for early signs of skin damage, have been the standard of care for many years. Despite this however, many of the RAT’s in clinical use, are reported to have low predictive value8 and do not always lead to effective prevention. Visual skin inspection also lacks reliability and is based upon the subjective interpretation of the individual assessing the skin9.
Tissue changes may occur below the observable skin level days before tissue breakdown and ulceration are visible at the skin surface10. These tissue changes that may lead to PI development are caused by inflammation triggered by prolonged pressure, shear forces, tissue deformation and ischaemia. The inflammation is stimulated over time, varying from minutes to hours and leads to a number of pathological changes. One early change is increased permeability of blood vessels which allows leakage of fluid from the vessels into the extracellular space. The leaked fluid accumulates as localised oedema also known as sub-epidermal moisture (SEM)10 and is therefore an early sign that tissue damage is happening which may lead to PI development. Patients with increasing SEM levels can then be managed with anatomically specific PI prevention strategies earlier than in the standard of care. An innovative and clinically proven technology known as the Provizio® SEM scanner , which provides an assessment of sub-epidermal moisture content as an early indicator of pressure injury risk is increasingly being adopted into clinical practice1,11,12.
The Provizio® SEM scanner is a handheld, wireless objective medical device that uses biocapacitance to identify increased risk of PI and gives insight to the clinician that a patient without visible external signs of tissue damage is at risk of PI development on the heel or sacrum. The Provizio® SEM Scanner has been demonstrated as an effective tool supporting the prevention of PI when used as an adjunct to standard of care with a weighted average reduction in PI incidence of 90.5% in acute care facilities13. Economic modelling studies based on a conservative range of assumptions also suggest that the implementation of the SEM scanner technology as an adjunct to standard of care is highly likely to lead to significant financial benefits and cost savings4,14