Objective
Conventionally, we use clinical physical assessment of flap perfusion and vessel flow during free flap harvesting, and after microscopic anastomosis of flap vessel, these methods were experience-dependent and repeated examination needed. Moreover, the analysis of arterial inflow and venous outflow of the free flap was remained to be studied. Previously, we reported our study of Indocyanine green analysis of arterial inflow and venous outflow in Anterolateral thigh flap. In this study we report Indocyanine green analysis of arterial inflow and venous outflow in Anterolateral thigh flap and different free flap.

Materials and Methods
Different free flap, including superficial circumflex iliac artery perforator (SCIP) flap, medial sural artery perforator (MSAP) flap, Anterolateral thigh flap , in which design and applied during reconstruction surgery were enrolled in this study. We injected Indocyanine green dye intravenously after all of the margins, perforators, and feeding vessels were dissected and before detachment. This study analyzes the time difference of the fluorescence observation image, using Photodynamic Eye (pde-neo or PDE; Hamamatsu Photonics K.K., Japan) , between the arterial inflow and the end of venous outflow and the entire flap perfusion. We also collected the same dataset after microscopic vessel anastomosis.

Results
The time-period of arterial inflow and venous outflow varied between not only in different types of free Anterolateral thigh flap but also in different free flaps. Besides, flap perfusion under Indocyanine green assessment was reliable compared to clinical flap examination.


Conclusion
In aid of the Indocyanine green assessment, we could further study different flap physiologic blood flow patterns, which may be related to flap circulation (blood supply), constituents (composition), contiguity(destination), construction(flow pattern), conditioning(such as delay, tissue expansion, prefabrication, sensate or functional) and conformation(conjoined, combined, tubed or special shapes). This is a preliminary report of our study and we hope to establish an objective and standardized tool to assist in clinical physical assessment.

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