pH, Exudate Composition and Temperature Measurement in Wounds - A Systematic Review
Objectives: To assess the potential of pH, exudate composition and temperature measurements in wounds to predict healing outcomes and to identify the methods that are employed to measure these characteristics in wounds.
Method: A systematic review based on the outcomes of a search strategy of quantitative primary research published in the English language was conducted in 8 research databases. The Evidence Based Literature (EBL) Critical Appraisal Checklist devised by Glynn (2006) was implemented to appraise the quality of the included studies.
Results: A total of twenty-four studies, three for pH (mean quality score 54.48%), twelve for exudate composition (mean quality score 46.54%) and eight for temperature (mean quality score 36.66%), were assessed as eligible for inclusion in this review. Findings suggest that reducing levels of pH in wounds, from alkaline towards acidic, are associated with improvements in wound condition. Metalloproteinase-9 (MMP-9), matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase (TIMP), neutrophil elastase (NE) and albumin, in descending order, were the most frequently measured analytes in wounds. MMP-9 emerged as the analyte which offers the most potential as a biomarker of wound healing, with elevated levels observed in acute or non-healing wounds and decreasing levels in wounds progressing in healing. Combined measures of exudate composites, such as MMP/TIMP ratios, also appeared to offer substantial potential to indicate of wound healing. Results suggest that temperature measurements are highest in non-healing, worsening or acute wounds and decrease as wounds progress into phases of healing. Methods used to measure pH, exudate composition and temperature varied greatly within each subject and, despite noting some similarities, the studies often yielded significantly contrasting results. A further limitation to the generalisability of the findings was the overall quality scores of the research studies which appeared suboptimal.
Conclusion: Despite the emergence of promising findings, there was insufficient evidence to confidently recommend the use of any of these measures as predictors of wound healing. pH measurement appeared as the most practical method for use in clinical practice to indicate wound healing outcomes. Further research is required to increase the strength of evidence in this field of research and to develop a greater understanding of the dynamics of wound healing. With this advanced knowledge, the value of measuring pH, exudate composition and temperature in wounds should become more apparent and a valid indicator for wound healing outcomes may be revealed.