The Role of pH and Temperature as Biomarkers of Wound Healing

Background: Non-healing wounds are a significant problem for both the individual and the health care system and with the rising population ageing demographic this is set to escalate further. Wound healing is a complex biological process that comprises haemostasis, inflammation, proliferation, and remodelling. Different types of cells are involved in this process including, macrophages, neutrophils, lymphocytes, fibroblasts, keratinocytes, and endothelial cells. Wound healing is fundamental to restore the integrity of the damaged tissue, and many factors impact on this process including temperature, pH and bacterial burden. The current assessment methods employed in practice are largely subjective and lack the ability to detect subtle, but important changes in the wound, which indicate that the wound is not progressing as it should. Incorporating objective methods into wound assessment has the potential to predict healing outcomes and to alert the clinician to the early onset of infection. A sudden increase in pH and wound temperature can indicate the presence of an infection. Infection is a major barrier to healing and an inaccurate diagnosis can lead to the overuse of antibiotics and broad-spectrum antimicrobials. Lowering the morbidity and mortality associated with wound infection is partially dependent on the early detection of infection. The main approach to combatting infection is to reduce harmful levels of bacteria in the wound by means of debridement, appropriate antimicrobial dressings and systematic antibiotics. Given the growing interest in the development of smart technology to enable objective assessment of wound healing, this thesis set out to explore the role of temperature and pH in wound healing. This thesis incorporated several elements.

Study One: The impact of pH and temperature on wound healing outcomes

Study Two: The impact of topical agents and dressing on pH and temperature

Study Three: The influence of pH and IODOFLEX◊ on wound healing

Study Four: The effect of inflammation management on pH, temperature and bacterial burden

Conclusion: This thesis incorporates four studies that explored the influence of pH and temperature in wound healing. The study emphasises the importance of using biomarkers such as pH and temperature to predict wound healing outcomes and to help guide treatment plans. Timely recognition of increased bacterial burden and infection enables the implementation of appropriate treatment plans. Notably, reductions in temperature and pH were associated with improved outcomes, whereas increases in pH and temperature were associated with increased bacterial burden and infection in the wound. The value of incorporating an objective approach to wound assessment incorporating the principles TIME was evident. Moreover, inflammation management using frequent sharp debridement and an antimicrobial agent had a positive effect on wound healing, as evidenced by a speedier reduction in pH, temperature, bacterial burden and wound size in Study Four.