RESUMO
BACKGROUND: Indocyanine green angiography (ICGA) is slowly replacing conventional methods of evaluating perfusion during flap surgery. Microcirculatory changes during flap elevation create a marked state of hypoperfusion intraoperatively leading to ICGA underestimation of tissue viability and consequent resection of viable tissue. We propose a novel method of flap warming to induce maximum vasodilation before performing ICGA to increase accuracy in assessing perfusion. METHODS: Submental flaps harvested on a single perforator were created in 8 pigs. ICG angiography was performed in the intraoperative phase (ICGA-C), after inducing maximum vasodilatation by warming the flap at 42⯰C (ICGA-W) and at 24H postoperative (ICGA-24). By setting a fluorescence threshold of 33% as indicative of necrosis, the flap surface deemed viable by ICGA was measured for ICGAC, ICGAW and ICGA24. The results were then compared to the actual flap survival observed clinically at 7 days. RESULTS: The mean of ICG-C predicted flap survival (FS-Câ¯=â¯49.17%) is 12.97% lower than the mean of actual flap survival on postoperative day 7 (FS = 62.14%). The mean difference between ICG-W and ICG-24 predicted flap survival (FS-W and FS-24) and actual flap survival in the postoperative day 7 (FS) is lower, 3.13% and 2.15%, respectively. Average perfusion recovery over 24â¯h was 10.83% (FS-24-FS-C). CONCLUSIONS: Conventional intraoperative ICGA underestimated perfusion in all cases. Warming the flap intraoperatively and achieving maximum vasodilation mitigates the effects of vasoconstriction and mimics the microcirculatory environment encountered at 24â¯h. Performing angiography after induced vasodilation improves ICGA assessment of flap perfusion.