Patient's weight-based indocyanine green dose for fluorescence angiography with led imaging system in left-sided colorectal resections.

BACKGROUND: One limitation of indocyanine green (ICG) fluorescence angiography (FA) is that, following intravenous administration, the dye produces residual background fluorescence impeding accurate perfusion assessment if a second injection is required. This study aimed to identify the optimal patient weight-based ICG dose able to create a strong fluorescent signal at the level of descending colon transection and, at the same time, to ensure none or minimal background fluorescence before second FA for perfusion assessment of colorectal anastomosis. METHODS: The first part of the study was used to define the ideal ICG doses, for overlay mode and monochromatic mode, to perform FA through the bisection method. In the second part of the study, the two doses were tested in 40 consecutive left-sided colorectal resections each, using an LED fluorescence system. Fluorescence intensity was assessed subjectively by a dose-blinded surgeon and objectively using image analysis software at three time points: after first ICG injection to identify descending colon transection line; before second injection, to define background fluorescence; after second injection, to define colorectal anastomosis fluorescence intensity. RESULTS: Sixteen patients were included in the first part of the study and 80 patients in the second one. The ICG doses equal to 0.027 mg/kg, for overlay mode, and 0.0108 mg/kg, for monochromatic mode, are associated with medium-to-maximum subjective and objective signal intensity during perfusion assessment of both descending colon, during transection line identification, and colorectal anastomosis. Background fluorescence was assessed a median of 19 (9-90 overlay, 10-96 monochromatic subgroups) minutes after dye injection, showing no recognizable fluorescence in overlay subgroup and minimal fluorescence in monochromatic subgroup. CONCLUSION: ICG doses calculated at 0.027 mg/kg, for overlay mode, and 0.0108 mg/kg, for monochromatic mode allow ideal intraoperative visualization during perfusion assessment of left-sided colorectal resections with ICG FA using an LED system.