How low can you go? Intraoperative microdosing of indocyanine green for fluorescence cholangiography during...

Fluorescence cholangiography (FC) with indocyanine green (ICG) enables real-time intraoperative visualization of extrahepatic biliary anatomy during laparoscopic cholecystectomy (LC). There is no consensus on the optimal ICG dose or timing of administration for LC. The goal of this study was to implement a simple intraoperative low-dose ("microdose") ICG protocol that facilitates non-inferior biliary visualization compared to a standard dose protocol to streamline perioperative workflows.

A retrospective review of a prospectively maintained database identified patients who underwent LC at our institution from 2021 to 2024. Microdose protocol patients were intravenously administered 0.5 mg ICG upon induction of general anesthesia, while standard protocol patients received 7.5 mg ICG 60-120 min preoperatively. Operative video from cases in both groups were reviewed to compare the frequency of cystic duct (CD), common bile duct (CBD), and common hepatic duct (CHD) visualization with FC. A 4-point Likert scale survey was completed for each case to compare ICG signal strength (1 = no signal; 4 = very strong), clarity from background interference (1 = cannot discern signal from background; 4 = no interference), and usefulness in clinical decision-making (1 = no benefit; 4 = essential).

A total of 100 patients were identified (N = 50 microdose; N = 50 standard). For microdose cases, the mean time from ICG administration to skin incision was 16.7 ± 5.6 min, and mean operative time was 47.4 ± 20.2 min. Compared to 50 standard dose cases, CD visualization before hepatocystic triangle dissection with the microdose protocol was 86.0% vs 88.0% (p = 0.99). The CBD and CHD were seen in all cases for both groups. There were no significant differences in average score for signal strength (3.6 ± 0.5 vs 3.7 ± 0.5, p = 0.32), signal clarity (3.4 ± 0.5 vs 3.3 ± 0.5, p = 0.32), or usefulness in clinical decision-making (4.0 ± 0.0 vs 4.0 ± 0.0, p = 0.99) between groups.

Microdose ICG can be given intraoperatively to provide excellent biliary visualization during laparoscopic cholecystectomy, eliminating the historical workflow of preoperative ICG administration.