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

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.

Preoperative visualization of midline-crossing subcutaneous arteries in transverse abdominal flaps using photoacoustic tomography.

BACKGROUND: Photoacoustic tomography is a noninvasive vascular imaging modality that uses near-infrared pulsed laser light and ultrasound to visualize vessels. We previously demonstrated the utility of photoacoustic tomography for anterolateral thigh flap surgery involving body-attachable vascular mapping sheets. However, it was not possible to obtain clear separate images of arteries and veins. In this study, we tried to visualize subcutaneous arteries that cross the midline of the abdomen, since these arteries are known to be important for obtaining large perfusion areas in transverse abdominal flaps. METHODS: Four patients scheduled to undergo breast reconstruction with abdominal flaps were examined. Photoacoustic tomography was performed preoperatively. The tentative arteries and veins were traced according to the S-factor, an approximate hemoglobin oxygen saturation parameter calculated using 2 laser excitation wavelengths (756 and 797 nm). Intraoperatively, arterial-phase indocyanine green (ICG) angiography was performed after abdominal flap elevation. Images of vessels speculated to be arteries by preoperative photoacoustic tomography were merged with those of intraoperative ICG angiography and analyzed in an 8 × 4-cm2 area below the umbilical region. RESULTS: The S-factor was used to visualize the midline-crossing subcutaneous arteries in all 4 patients. A matching analysis compared preoperative tentative arteries according to photoacoustic tomography with ICG angiography results in the 8 × 4-cm2 area below the umbilical region and indicated a 71.3-82.1% match (average: 76.9% match). CONCLUSIONS: This study demonstrates that the S-factor, a noninvasive, label-free imaging modality, can be used to successfully visualize subcutaneous arteries. This information can aid in selecting perforators for abdominal flap surgery.

Clinical assessment of early mobilization after head and neck free flap reconstruction: A retrospective case-control study.

PURPOSE: We examined whether there were any differences in perioperative complications between patients who mobilized on the first postoperative day (early mobilization) and those who mobilized on the second postoperative day after head and neck reconstruction using free tissue transfer. METHODS: In the control group (n = 74), patients were instructed to mobilize on the second postoperative day (April 2019-March 2020), while in the early mobilization group (n = 101), patients were instructed to mobilize on the first postoperative day (April 2020-March 2021). Mobilization was defined as maintaining a standing position or walking. Clinical data were collected from medical records and retrospectively analyzed. RESULTS: There were no significant differences in clinical background factors, with the exception of intraoperative blood loss volume. The proportion of patients who successfully mobilized on the day of instruction was significantly lower in the early mobilization group (89.1% vs. 98.7%). One case of total flap loss and four cases of partial flap loss occurred in the control group, and three cases of partial flap loss occurred in the early mobilization group. There was no significant difference in partial or total flap loss between the two groups. There were no significant differences in other perioperative complications (wound infection, postoperative bleeding, and delirium) between the two groups. The median postoperative hospital stay was 24.5 and 25.0 days in the control and early mobilization groups, respectively. CONCLUSION: In this study, early mobilization on the first day after head and neck free flap reconstruction was safe and feasible.