Analysis of localized erythema using clinical indicators and spectroscopy

Localized erythema is regularly used as an indicator of post-ischemic events, including reactive hyperemia and Stage I pressure ulcers. The National Pressure Ulcer Advisory Panel definition of a Stage I ulcer includes both visual and nonvisual indicators in part to improve identification in darkly pigmented skin. A prospective, repeated-measures design was used to collect information on pressure-induced erythema that includes reactive hyperemia and Stage I pressure ulcers with an emphasis on distinguishing indicators in light and dark skin The relationships among clinical indicators (skin assessments) and results from tissue reflectance spectroscopy, as well as the clinical utility of spectroscopy for discerning tissue blanching status, were examined in a convenience sample of 76 inpatients and outpatients (95 test/control site pairs). Chi-square analysis and generalized logistic models were used to identify relationships and distinguishing characteristics of erythema. Analysis of variance was used to analyze blanching using spectroscopy. Nonblanching sites were more likely to be persistent erythema (c2=5.3; P = 0.021) but exhibited no relationships to temperature, tissue resilience, or disability. Erythema in subjects with dark skin was more likely to be nonblanching and have poor resilience. Spectrographic analysis of blanching found significant differences across skin pigmentation (P = 0.0001) and blanching status (P = 0.019). These results reinforce the belief that dark skin must be assessed differently than light skin and indicate that clinicians should use persistence of erythema rather than blanching status to judge incipient pressure ulcers. These results validate the use of visual and nonvisual indicators included in the National Pressure Ulcer Advisory Panel Stage I pressure ulcer definition.