Impact of Skin Tone and Cupping on Erythema and Thermal Imaging Measurements

Erythema commonly presents as the reddening or discoloration of the skin due to hyperemia in tissue under pressure and is assessed in skin evaluations to detect early signs of pressure injuries (PrIs). While the use of thermography has been shown as a promising tool for the identification of PrIs, the correlation of temperature and erythema changes have not been consistent across all skin tone categories. Therefore, the objective of this study was to evaluate how thermography and colorimetry can track temperature and erythema changes following cupping across a diverse set of skin tones. Tissue changes over a bony prominence were induced by using a cupping device and maintaining − 30 kPa for 5 minutes. After this, thermal images and colorimeter measurements were taken starting immediately post-cupping and repeated every minute for 7 minutes. No significant differences in temperature change were observed across BMI category, sex, or skin tone post-cupping. Measurements of change in erythema also did not vary across sex or BMI category, but did vary significantly across skin tone category (p < 0.001). These findings demonstrate that thermal imaging detects underlying tissue changes that visual assessment cannot capture, supporting its use as a complement to, rather than replacement for, clinical assessment.