Fig. 2

Overall view of the oxygen saturation and tissue congestion evaluation device. a Appearance of the display of this device. The upper panel displays tissue oxygen saturation, and the lower panel displays T-Hb index as a congestion index. By placing the detector in close contact with the target organ, these two parameters are immediately analyzed and displayed. These values can be measured repeatedly in real time without the need for reagents. b Overview of the internal structure of the device’s detector. Tissue oxygen saturation quantifies the value obtained by projecting the target tissue from two different photodiodes. c Representative images of an intraoperative real time evaluation for oxygen saturation & T-HbI of the gastric tube obtained during esophagectomy