Is the Licox PtO2 System Reliable for Free Flap Monitoring? Comparison between Two Cohorts of Patients

Background Flap failures can derive from arterial or venous occlusion due to thrombosis, external compression, vessel kinking, or hematoma, etc. Any delay between the detection of flap compromise and surgical re-exploration significantly decreases the free flap salvage rate. Free Flap monitoring is crucial for early recognition of vascular complications. Licox® PtO2 is a minimally invasive monitoring system for continuous measurement of tissue oxygen tension in all types of free tissue transfers. Our study compares two consecutive series of patients undergoing microsurgical reconstruction monitored with standard clinical bedside surveillance and with the Licox® PtO2 system regarding flap loss and flap salvage, sensitivity and specificity.

Methods: We performed a prospective study of all patients undergoing microsurgical reconstructions between 2016 and 2017. Group 1 included 43 patients that underwent standard clinical bedside postoperative flap monitoring while group 2 included 44 consecutive patients also monitored with Licox® PtO2 system.
Flap complications such as return to theatre for vascular compromise, partial and total flap loss and flap salvage rate were analyzed. We performed the re-exploration of the flap in group 2, when the PtO2 values continuously dropped for at least 50% of their original value in 30 minutes or reached levels lower than ten mmHg while in group 1, clinical signs of arterial/venous compromise had to be present.

Differences in categorical data were analyzed using Chi-square test or Fisher's exact test when appropriate. Differences were considered significant if P-value was <0.05. Statistical analyses were carried out using software R (the R Foundation for Statistical Computing; Version 3.3.2, 2016).