Thermal measurement of erythema across skin tones: Implications for clinical identification of early pressure injury.

Aim: To assess the effectiveness of thermography, colorimetry, and oximetry at detecting temperature changes after erythema induction across diverse skin tones in healthy adults.

Materials and methods: Erythema was induced at the forearm and ulnar head (UH) using a cupping device. Temperature via thermal image, erythema value via colorimeter, and oxygen saturation via oximeter were collected immediately and 5-10 min (delayed) after cupping at both sites.

Results: At the forearm, the delayed timepoint was significantly warmer than baseline. At the UH, the immediate timepoint was significantly colder than baseline. Erythema increased at both timepoints and both locations. The correlation between temperature change and erythema change was weak. Change in temperature did not differ between skin tone groups. The Intermediate Low Eumelanin skin tone group had more change in erythema compared to the Intermediate Mid (i.e., darkest) skin tone group immediately after cupping at the UH and at the delayed timepoint at the forearm.

Conclusions: This study observed differences in the change of erythema across skin tones but did not observe differences in temperature across skin tones. Given high variability in results, it is premature to conclude thermal imaging works equally well across all skin tones. Further research is necessary to validate the effectiveness of thermal imaging in diverse populations. Results suggest visual erythema may be a problematic indicator as less erythema was consistently noted in participants with dark skin tones. The potential of technology to increase our ability to detect erythema warrants further investigation.