Flap Viability Evaluation Using a Tissue Oximetry Camera as an Alternative to Indocyanine Green Fluorescence Imaging

Abstract

Summary: Indocyanine green (ICG) fluorescence imaging is useful for assessing flap viability; however, it is associated with a risk of anaphylactic shock, even in patients with no history of drug allergies. SnapshotNIR is a noncontact, camera-type handheld tissue oximeter that can measure the tissue oxygen saturation of the body surface. The device emits red and near infrared light wavelengths and then optimizes the measurement of the differential reflectance from oxygenated and deoxygenated hemoglobin, and StO2 is calculated. A 20 × 15 cm surgical field can be evaluated in less than 3 seconds by holding the camera at a distance of 30 cm. We applied this device at zone II in a deep inferior epigastric perforator (DIEP) flap, and compared the findings with the border of flap perfusion detected by ICG imaging. Left breast reconstruction using a free DIEP flap was performed for a 60-year-old woman. The DIEP flap was vascularized by a perforator vessel coursing to the right abdominis muscle. First, Diagnogreen (5 mg; Daiichi Sankyo Co., Tokyo, Japan) was intravenously injected, and the ICG fluorescence perfusion border detected by PDE-neo (Hamamatsu Photonics, Hamamatsu City, Shizuoka, Japan) was determined. The ICG border was defined by two reconstructive surgeons after fluorescence had spread out for 2 minutes. Next, zones Ⅱ and Ⅳ of the DIEP flap, contralateral to the perforator, were evaluated using photographs obtained by SnapshotNIR. There were significant StO2 value differences between the ICG-negative area and ICG-positive area. This device can be widely applied in the noninvasive evaluation of flap viability.