Sub-Epidermal Moisture and the Role of Inflammation in Pressure Injury 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 impact^2,3,4, 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 practice^1,11,12.  

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 savings^4,14

References

_{1.Ore N, Carver T (2020) Implementing a new approach to pressure ulcer prevention.  Journal of Community Nursing, 34,4}

_{2.Dealey C, Posnett J, Walker A (2012). The cost of pressure ulcers in the United Kingdom. Journal of Wound Care; 21(6):261-266.}

_{3.Brem H, Maggi J, Nierman D et al. High cost of stage IV pressure ulcers. Am. J. surg. 2010; 200:473-477}

_{4.Padula WV, Malaviya S, Hu E, Creehan S, Delmore B, Tierce JC (2020).  The cost effectiveness of sub-epidermal moisture scanning to assess pressure injury risk in U.S. Health Systems.  Journal of Patient Safety and Risk Management. 0(0):1-9. DOI:10.1177/2516043520914215}

_{5.AHRQ. Never Events. 2017. https://psnet.arhq.gov/primers/primer/3/never-events. Accessed August 2017}

_{6.Centre for Medicare and Medicaid Services (CMS) (2013)}

_{7.European Pressure Ulcer Advisory Panel, National Pressure Ulcer Advisory Panel & Pan Pacific Pressure Injury Alliance.  Prevention and Treament of pressure ulcers/injuries:Clinical Practice Guideline.  Emily Haesler (Ed.). EPUAP/NPIAP/PPIA:2019}

_{8.Moore ZEH, Patton D.  Risk assessment tools for the prevention of pressure ulcers.  Cochrane Database of Systematic Reviews 2019, Issue 1.  Art No.:CD006471.DOI:10.1002/14651858.CD006471.Pub4}

_{9.Samuriwo R. & Dowding D (2014)Nurses’ pressure ulcer related judgements and decisions in clinical practice: A systematic review.  Int J Nurs. 51(12):1667-85}

_{10. Ross G, Gefen A (2019).  Assessment of sub-epidermal moisture by direct measurement of tissue biocapacitance. Medical Engineering and Physics. Vol 73:92-99}

_{11. Smith G (2019) Improved clinical outcomes in pressure ulcer prevention using the SEM Scanner.  Journal of Wound Care. Vol 23(5)}

_{12. Raizman R, MacNeil M, Rappl  (2018).  Utility of a sensor-based technology to assist in the prevention of  pressure ulcers: A clinical comparison.  Int Wound Journal. https://doi.org/10.1111/iwj.12974}

_{13. Wood Z (2020). Real World Evidence Accepted and presented at EWMA Conference}

_{14. Gefen A, Kolsi J, Grainger S, Burns M (2020) Modelling the cost benefits arising from technology-aided early detection of pressure ulcers.  Wounds International. Vol 11 (1): 22-29}