Intraoperative ICG-based fluorescence-angiography in head and neck reconstruction: Predictive value for impaired perfusion of free flaps

The aim of this study was to prove the hypothesis that intraoperative fluorescence-angiography using indocyanine-green (ICGFA) can be used to predict the occurrence of perfusion-associated complications following microvascular reconstruction. Consecutively perioperative data of patients who received microvascular reconstruction of the head and neck region and underwent ICGFA immediately after anastomosis was established were analyzed. The flow parameters analyzed in the investigation were (1) the baseline (Int_Min) and (2) peak intensity (Int_Max) of fluorescence, (3) the quotient of the two aforementioned parameters (F_max/min) as an expression of the relative total increase, (4) the absolute difference in the two parameters (Diff_Int) in terms of amplitude, (5) the duration of the intensity increase (T_Rise) until the peak, and (6) the percent intensity increase per second (Rise/sec_rel). Within the first 2 weeks postoperatively, every flap complication was documented. Subsequently, statistical analysis of the flap outcome was performed based on the flow parameters obtained intraoperatively. Data of 67 patients (male/female: 41/26) with an average age of 64 years (range 29-84 years) were analyzed. In 10 of these patients, postoperative perfusion-associated complications were observed (arterial/venous/microcirculatory: 4/3/3; p = 0.12). The analysis of the intraoperatively obtained flow parameters showed a significant difference in the ratio of maximum and minimum intensity in arterial pedicle perfusion (F_max/min) of patients with and without complications (with vs. without complications: 2.3 ± 1.0 vs. 5.0 ± 4.9; p < 0.01) and strong correlation of the mentioned parameter with the occurrence of perfusion-associated complications (odds ratio = 0.27; p = 0.01). The ratio of maximum and minimum intensity (F_max/min) is a predictor for postoperative venous stasis, arterial hypoperfusion and impaired microcirculation of a microvascular flap. Anastomoses with F_max/min <2.85 should be revised. However, a high technique sensitivity has to be considered, due to which sufficient hemostasis and reduction of motion artefacts have to be taken into account in order to obtain useable data.