Evaluation of four non-invasive methods for examination and characterization of pressure ulcers

Background: Pressure ulcers are globally of major concern and there is need for research in the pathogenesis for early intervention. Early studies have suggested existence of a hypo-echogenic subepidermal layer at the location of pressure ulcers, visualized by ultrasound scans. As a continuation, we here report on usability of four non-invasive techniques for evaluation of pressure ulcers. Methods: Fifteen pressure ulcers in stage 0-IV were examined using four different non-invasive techniques [redness index, skin temperature, skin elasticity (i.e. retraction time), and ultrasound scanning]. Measurements were made at the ulcer, 5 cm from the ulcer, and at a reference skin location without ulcers. Results: The redness index was, in all cases, higher at the ulcers than at the reference skin. Temperature measurements were rather scattered. Ultrasound scans showed a hypo-echogenic subepidermal layer at all pressure ulcers, but none at the reference points. The skin retraction time was often higher at the location of a pressure ulcer than at the reference location. We found no correlation between the stage of the ulcers and temperature, redness index, subepidermal layer thickness, or retraction time. Conclusion: We conclude that temperature and elasticity measurements do not alone characterize ulceration severity, although redness index in some cases provides a useful indication. We assume that a subepidermal layer found on ultrasound images may be a measure of the pressure that the skin has been subjected to, rather than of the severity of the pressure ulceration. This method may be useful for predicting whether the skin is at risk of developing pressure ulcers. More studies are needed.