A Reliable Method for the Monitoring of Buried Free Flaps Using Near-Infrared Spectroscopy

Abstract

Background In recent years, there has been a shift toward nipple-sparing mastectomy (NSM) techniques which often negates the need for reconstruction with exposed cutaneous donor flap tissues. Although techniques for the monitoring of buried flaps have been proposed, none have been able to provide the benefits that come with cutaneous monitoring via near-infrared spectroscopy (NIRS). Therefore, we herein propose a novel method for monitoring deepithelialized flap tissues deep to the mastectomy flaps using NIRS technology. Methods An NSM with free flap reconstruction was performed. The flap was designed with a skin island for placement of a cutaneous NIRS probe. Next, a silicone NIRS probe was placed on a deepithelialized portion of the flap under the mastectomy flap. The readings from this tunneled device were then compared to the control measurements obtained from the cutaneous NIRS monitor. This procedure was performed on three consecutive patients. The changes in StO2 recorded from both devices were compared using a paired, two-tailed Student's t-test. Results During flap monitoring, there were no issues with probe dislodgement and signal quality averaged greater than 90. Furthermore, probe removal was easily accomplished at bedside. There was no harm to the mastectomy skin flaps by affixing the probe and the pocket which contained the probe quickly closed down after removal. Using the Student's t-test, a p-value of 0.995 was calculated indicating no statistically significant difference between the StO2 readings from the cutaneous and the tunneled probes. Conclusion By using this novel method, NIRS technology can reliably be applied to the monitoring of buried free flap tissues. The proposed technique could be applied to a variety of flaps beyond the realm of breast reconstruction and may prove to be particularly useful in the setting of head and neck reconstruction. The results of this study suggest that high quality postoperative flap monitoring is possible without compromising the aesthetic result.