Postoperative Monitoring by Near-Infrared Spectroscopy in Transferred Free Tissue

1, 2). Near-infrared spectroscopy (NIRS) is a noninvasive, sensitive, and reliable method increasingly used for postoperative monitoring.Several types of NIRS instruments are commercially available, and each instrument has slight differences in the measurement algorithms.A Toccare device (Astem, Tokyo, Japan) was used in this study.This device measures regional oxygen saturation (rSO2) and total hemoglobin index (T-HbI), which indicates the total Hb concentration.The device detects 2 wavelengths (770 and 830 nm) with 2 detectors (6 and 8 mm away from the light source); the tissue penetration depth of near-infrared light can be up to 5 mm subcutaneously, with a sensor size of < 1 cm 2 3) .The system can be monitored even when the flap size is small or when the flaps are placed in the