The exploration of tissue pH and its relationship to bacterial contamination

by Shorrock, Susan M.

Presently, plastic surgeons do not have a methodology for non-invasive, real-time assessment of wound tissue properties. It is of extreme importance to objectively determine the health of wound tissue and the level of bacterial infection before surgical closure of the wound is attempted. Wounds that possess significant areas of low blood perfusion and high levels of bacteria will not be successfully grafted. Thus, this research aims at identifying and testing a measurable parameter for the assessment of tissue properties in acute and chronic wounds. Tissue pH, which is easily measured, has been proven to detect the presence of tissue ischemia. In this research, the variations of tissue pH levels in patient wounds and the relationship between tissue pH and bacteria levels were explored. Micro-combination pH electrodes were tested; software algorithms for acquiring and processing raw tissue pH data were developed; and calibration, sterilization, animal, and clinical protocols were designed. Animal and clinical studies were performed. Small variations in tissue pH values were found within patient wounds and between patient cases. A qualitative relationship between tissue pH levels and bacterial contamination was identified. As the bacterial contamination rises, the average tissue pH level tends to decrease. A methodology that clinicians can use to efficiently measure tissue pH in wounds was developed. This research provides preliminary work in an area that has not been previously explored. It was shown that tissue pH measurements can be acquired efficiently, noninvasively, and with no discomfort to the patient. The incorporation of tissue pH measurements into the evaluation of wounds will contribute to providing an objective measure of the health of the tissue and aid plastic surgeons in the development of patient treatments. ii