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

To present a cross-sectional cohort study conducted to assess the association between wound pH, local infection, and deep/surrounding infection.

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

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.

BACKGROUNDWounds 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.

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.

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 (ΔT) value between patients with deep/surrounding wound infection and three or more positive STONEES criteria (P = .002).

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.