A Device to Predict Short-Term Healing Outcome of Chronic Wounds

Abstract

Objective: While myriads of studies have suggested that a survey of wound pH environment could indicate wound healing activities, it is not clear whether wound alkalinity can be used as a prognostic indicator of nonhealing wounds. Currently available systems cannot reliably assess the pH environment across wounds, which is the objective of this study. Approach: A disposable device, DETEC^® pH, was developed and characterized on its ability to map wound alkalinity by pressing a freshly recovered wound dressing against its test surface. By comparing the wound's alkalinity and size reduction rates (∼7 days) following pH measurement, we assessed the capability of wound alkalinity to prognosticate subsequent short-term wound size reduction rates. Results: The device had high accuracy and specificity in determining the alkalinity of simulated wound fluids soaked onto wound dressing. The type of wound dressing type had an insignificant effect on its detection sensitivity. Upon testing discarded wound dressings from human patients, the device quickly determined alkaline and acidic wounds. Finally, statistical analyses of wound size reduction rates in wounds with various alkalinities confirmed that wound alkalinity has a strong influence on, at least, short-term wound healing activity. Innovation: Without directly contacting the patient, this device provides a quick assessment of wound alkalinity to prognosticate immediate and short-term wound healing activities. Conclusion: DETEC^® pH may serve as a prognosis device for wound care specialists during routine wound assessment to predict wound healing progress. This information can assist the decision-making process in a clinical setting and augur well for chronic wound treatment. DETEC^® pH can also be used as an aid for home health care nurses or health care providers to screen nonhealing wounds outside clinics.

Keywords: chronic wound; clinical study; healing rate; wound dressing; wound pH.

Wenjing Hu, PhD

Liping Tang, PhD

Figure 1.

(A) Overview of DETEC^® pH. (B) DETEC^® pH testing scheme. Existing dressing is removed from the wound and placed on the wound dressing holder on the device. Within 60 s, wound imprint from the dressing appears on the film, with the color map reflecting the pH pattern of wound environment.

Figure 2.

DETEC^® pH color change after contacting a wound gauze soaked in SWF with various pH (upper panel). Change in color in response to various pH (lower panel). SWF, simulated wound fluid.

Figure 3.

Change in pH of SWF during 7 days incubation with a wound dressing (Curity Sponges).

Figure 4.

Effect of wound dressing on SWF with (A) pH 4, (B) pH 6, and (C) pH 8. Images of DETEC^® pH output for each dressing at a specific pH is shown.

Figure 5.

Clinical testing of DETEC^® pH in (A) normally healing wound and (B) slow healing chronic wound. The areas of pH reading are traced with blue and red lines on corresponding wound image and DETEC^® pH, respectively.

Figure 6.

Effect of wound alkalinity on rate of change in wound size. (A) The distribution of wound sizes. (B) Comparison of rate of change in wound size between alkaline and acidic wounds was calculated as (wound size at visit 2 − wound size at visit 1)/(wound size at visit 1). (C) Influence of wound sizes on wound alkalinity-dependent rate of change in wound size.

Figure 7.

Box plot showing the distribution of wound size reduction rates based on wound alkalinity. (A) Distribution of wound size reduction rates between alkaline and acidic wounds. (B) Influence of wound sizes on the distribution of wound size reduction rates between alkaline and acidic wounds.