Critical comparison of transcutaneous PO2 and tissue pH as indices of perfusion.

A critical laboratory evaluation of transcutaneous PO2 monitoring and tissue pH monitoring in lower abdominal island flaps based on the superficial inferior epigastric vessels in rabbits revealed that transcutaneous PO2 values correlate poorly with tissue survival under circumstances of decreased arterial inflow. The inability of the transcutaneous PO2 monitor to accurately predict viability of the flaps in this study is attributed to physiologic changes in the microcirculation and not to instrument error. Tissue pH was, in all instances, a reliable index of the perfusion status of the flaps.