Using Technology to Make Strides in Pressure Ulcer Identification

Pressure ulcers are most often identified using visual assessment of the skin, which assumes a top down development, with stage one indicating redness of the skin and stage 4 indicating full tissue destruction. However, work of Agam and Gefen (2007), Ceelen et al (2008) and Oomens et al (2015), has shown us that pressure ulcers most often occur in the deeper layers of the tissues emerging outwards towards the skin surface. Thus, what we think is a stage 1, may actually be an emerging stage 4 and as such the staging system is confusing and largely unhelpful. Sub-epidermal moisture is related to the quantity of skin and tissue water. Inflammation and oedema that result from tissue damage, and that indicate excess of interstitial fluid in the tissues can be measured through the use of instruments that use electric and electromagnetic signals. Surface electrical capacitance of the skin is determined by the impedance of the skin to electrical forces, and thus can reflect oedema and water content of the epidermal and sub-epidermal tissues (Oliveira & Moore 2017). We have been working with Sub Epidermal Moisture measurement as a predictor of early pressure ulcer damage for a number of years and our results have identified pressure ulcers up to 7 days earlier than visual skin assessment. The value of this earlier recognition of pressure ulcer presence is that we can more quickly identify patients who are not tolerating the pressure and shear forces they are exposed to. As a result we can alter the pressure ulcer prevention strategies that are being offered and furthermore, can readily evaluate the patients’ responses to the enhanced prevention strategies employed. At its essence the SEM measurement technology has enabled us to make significant strides in pressure ulcer identification, outcomes of our research work has the potential to significantly impact on the drive for zero pressure ulcers. 


  • AGAM, L. & GEFEN, A. 2007. Pressure ulcers and deep tissue injury: a bioengineering perspective. J Wound Care, 16, 336-42.
  • CEELEN, K. K., STEKELENBURG, A., LOERAKKER, S., STRIJKERS, G. J., BADER, D. L., NICOLAY, K., BAAIJENS, F. P. T. & OOMENS, C. W. J. 2008. Compression-induced damage and internal tissue strains are related. Journal of Biomechanics, 41, 3399-404.
  • OLIVEIRA, A. L., MOORE, Z., O'CONNOR, T. & PATTON, D. 2017. Accuracy of ultrasound, thermography and subepidermal moisture in predicting pressure ulcers: a systematic review. J Wound Care, 26, 199-215.
  • OOMENS, C. J., BADER, D., LOERAKKER, S. & BAAIJENS, F. 2015. Pressure Induced Deep Tissue Injury Explained. Annals of Biomedical Engineering, 43, 297-30
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