Development of a minimally invasive microvascular ischemia monitor: drift reduction results

The objective of the authors' research is to develop a pH based, ischemia measuring system which will be used for postoperative monitoring of transplanted tissue over a four day period. Currently, most pH monitors are difficult for hospital personnel to operate and lack sufficient long-term stability, resulting in false readings of tissue pH (drifts >/spl plusmn/0.48 pH units per 100 hours). An electronic multi-channel pH measuring device which interfaces with a laptop computer was constructed. The system uses an algorithm to compensate for inherent pH measurement instabilities. This is accomplished using separate pH reference electrode channels from which multiple measurements are averaged. The authors' system provides tissue pH measurements that are sufficiently stable during 96 hour postoperative monitoring periods.