This demonstrates the potential additional value of ICG videoangiography including FLOW 800 analyses in the postoperative monitoring of transplanted flaps. © 2016 Wiley Periodicals, Inc. Microsurgery 37:235-242, 2017.

No abstract

The effects of gradual vascular occlusion on the blood supply of perfused areas are poorly described. Information relating to the comparison of flap monitoring techniques is lacking. Varying stenotic conditions (0%, 25%, 50%, 75% and 100%) were generated on purpose at the A. and V. femoralis in the rat model. Analyses included flowmeter, simultaneous laser-Doppler flowmetry and tissue spectrophotometry (O2C) and indocyanine green-(ICG-) videoangiography with integrated FLOW 800 tool. A Random Forests prediction model was used to analyse the importance of each method to diagnose the stenotic conditions. The ability to discriminate and to accurately estimate the probability of stenosis was assessed by Receiver Operating Characteristic (ROC) curves and calibration plots. Blood flow changes for all modalities were described in detail. Flowmeter displayed earliest a linear decrease as a result of increasing stenosis. A stenosis of 50% degrees was most difficult to detect correctly. The combination of flowmeter and ICG-videoangiography showed high diagnostic power for each stenotic situation (area under the Roc > 0.79). Flowmeter and ICG-videoangiography showed to be most relevant in detection of varying stenotic conditions and may change the clinical outcome. The O2C showed less effect on varying stenotic situations as the only surface monitoring device. The microvascular free tissue transfer has revolutionised reconstructive microsurgery and has improved the patients' functional outcome 1. Despite the well documented co-morbidities of patients undergoing head and neck surgery, free flap surgery has contributed to a continuous improvement in the patient-reported and clinical outcomes 2-4. Due to the significant patient co-morbidities and the complexity of the operations, this patient cohort has a high free flap failure rate. A successful outcome necessitates a detailed pre-, intra-and postoperative patient screening in addition to the free flap monitoring, for at least the first 72 hours, postoperatively. The reasons for free flap failures are commonly vascular (thrombosis, endothelial damage) or extravascular, (hematoma, kinking, twisting) in origin. Flap necrosis invariably leads to a prolonged hospital stay and may result in mortality due to poor physiological reserves. There is a definitive window of surgical intervention that must not be missed, for the salvage operation to be successful 5,6. For this reason, the routine postoperative free flap monitoring has to be effective, reproducible and reliable. Free flap monitoring techniques vary and may include the clinical observation, pinprick testing and handheld Doppler 7. More sophisticated, objective methods include simultaneous