Impact of skin tone and cupping on erythema and thermal imaging measurements

Erythema is commonly assessed to detect early signs of pressure injuries (PrIs). Thermography has emerged as a promising tool for PrI detection; however, correlations between temperature changes and erythema have not been consistent across skin tones. This study evaluated whether thermography and colorimetry could track temperature and erythema changes following cupping across diverse skin tones. Tissue changes were induced over a bony prominence using a cupping device at - 30 kPa for 5 min. Thermal images and colorimeter measurements were collected immediately after cupping and at one-minute intervals for seven minutes. Temperature at the cup rim increased 0.37 °C before returning to baseline while temperature dropped significantly at the cup center (- 0.54 °C), returning to baseline after 3-4 min. Erythema index increased immediately post-cupping (1.49 c.u.) and remained elevated throughout the seven-minute period. Neither temperature nor erythema changes varied by BMI or sex. Only erythema differed significantly across skin tone categories (p < 0.001). Regional variation in temperature responses suggests compressive and tensile stresses may generate distinct tissue effects with clinical relevance. Thermal imaging can identify subtle tissue changes not apparent during visual assessment, supporting its use as a complement to clinical evaluation for PrI prevention.