Tissue Oximetry Readings Accurately Predict Late Complications in Patients Undergoing Free Flap Breast Reconstruction: Exploring the Optimal Cut Point Value

Background The use of tissue oximetry for monitoring following free tissue transfer has become a common practice across the United States to facilitate early detection of poor flap perfusion in the postoperative setting. There is no consensus on the optimal value, below which there is a higher chance of wound complications in patients undergoing free flap breast reconstruction. Methods Patients undergoing free flap breast reconstruction from 2015 to 2018 were retrospectively reviewed. Patients who returned to the operating room for a revision of the anastomosis were excluded from analysis. Patients were divided in two groups based on the development of late complications. Those were defined as fat necrosis, wound dehiscence, or distal flap ischemia/necrosis that developed after discharge from the hospital. Mean percutaneous oximetry readings of the first 24 hours were recorded and the mean change from the initial reading was calculated. The correlation between tissue oximetry change and development of complications was explored. Results A total of 120 patients were identified. The mean age was 53, while the mean body mass index was 33. A total of 38 patients developed late wound complication. History of smoking, diabetes mellitus, neoadjuvant radiation therapy, and the mean change of the tissue oximetry reading were identified as independent predictors of wound complications. The absolute number of the tissue oximetry reading did not predict late complications. A multivariate analysis revealed that patients who experienced a mean decrease < 15% from the initial reading during the first 24 hours were significantly more likely to develop late flap-related wound complications. Conclusion In patients undergoing free tissue breast reconstruction, tissue oximetry readings do not predict late wound complications. However, the mean change at 24 hours from the initial reading does. A decrease of <15% in tissue perfusion was associated with a significant increase in the probability of developing flap-related wound complications.