Objective: To analyze the blood oxygen concentrations (StO 2 ) of different stages of pressure injury (PI) tissue using hyperspectral images to serve as a guideline for the treatment and care of PIs.
Methods: This study used a prospective design. A total of 30 patients with sacral PIs were recruited from the rehabilitation ward of a teaching hospital. The authors used a hyperspectral detector to collect wound images and the Beer-Lambert law to estimate changes in tissue StO 2 in different stages of PI.
Results: The tissue StO 2 of healthy skin and that of stage 1 PI skin were similar, whereas the tissue StO 2 of the wound in stage 2 PIs was significantly higher than that of healthy skin and scabbed tissue (medians, 82.5%, 74.4%, and 68.3%; P < .05). In stage 3 PIs, StO 2 was highest in subcutaneous tissue and adipose tissue (82.5%) and lowest in peripheral scabs (68.35%). The tissue StO 2 was highest in subcutaneous tissue in stage 4 PIs, and this tissue was red in the hyperspectral spectrum. The scab-covered area of unstageable PIs had the lowest StO 2 of all PI tissue types (median, 44.3%).
Conclusions: Hyperspectral imaging provides physiologic information on wound microcirculation, which can enable better evaluation of healing status. Assessing tissue StO 2 data can provide a clinical index of wound healing.
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