Associations Among Skin Surface pH, Temperature, and Bacterial Burden in Wounds

BACKGROUND Wounds with a higher pH often demonstrate lower rates of healing. Local and deep/surrounding infection can be diagnosed with the validated NERDS and STONEES clinical signs, respectively. This study assessed the association between wound pH, local infection, and deep/surrounding infection. METHODS A 100-patient prospective cross-sectional cohort study was conducted with leg and foot wounds. Wound pH was measured using pH indicator strips. The wounds were assessed for clinical signs of local or deep/surrounding infection with the NERDS and STONEES criteria, respectively. Temperature measurements were documented with a handheld infrared skin thermometry device at the wound/periwound site, the equivalent site on the opposite side of the same leg/foot, and the wound mirror image site on the opposite leg/foot. RESULTS There was no significant difference in the mean wound bed pH in patients with superficial critical colonization and those without (P = .837). The wound and periwound maximum temperature measurements were compared with an equivalent temperature on the mirror image on the opposite leg. There was a statistically significant difference in the mean temperature (Delta T) value between patients with deep/surrounding wound infection and three or more positive STONEES criteria (P = .002). CONCLUSIONS Nontouch infrared thermometry comparing maximum mirror image wound temperatures versus the opposite extremities when combined with two or more other STONEES criteria is a significant indicator of deep and surrounding infection. Surface wound bed pH indicator strip measurements do not correlate with local wound infection using the NERDS criteria. GENERAL PURPOSE To present a cross-sectional cohort study conducted to assess the association between wound pH, local infection, and deep/surrounding infection. TARGET AUDIENCE This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. LEARNING OBJECTIVES/OUTCOMES After participating in this educational activity, the participant should be better able to: 1. Synthesize the background information associated with the study assessing the association between wound pH, local infection, and deep/surrounding infection. 2. Summarize the results of the study presented here.