Standardized 6-minute Indocyanine Green Angiography in Equivocal Digital Perfusion: A Prospective Feasibility Study

In complex digital trauma, clinical perfusion signs are unreliable when arteries are less than 1 mm or venous outflow is uncertain. We evaluated the feasibility and diagnostic accuracy of a standardized 6-minute indocyanine green fluorescence angiography workflow with prespecified temporal thresholds to translate equivocal clinical signs into actionable hemodynamic information.

We performed a prospective single-center cohort study at Padua University Hospital from January 1, 2022, to December 31, 2024. Adults with Tamai zone II-V injuries and equivocal perfusion underwent Verdye 0.30 mg/kg injection. Four patterns were defined a priori from pulp fluorescence: early perfusion, delayed perfusion, delayed washout, and absent perfusion. Management followed a prespecified algorithm.

Of 142 injured digits screened, 30 digits in 26 patients met eligibility. First-pass allocation was early perfusion in 12, delayed perfusion in 7, delayed washout in 7, and absent perfusion in 4. Intraoperative review prompted management changes in 12 digits, most commonly venous augmentation for delayed washout. All 26 threshold-positive digits survived at 30 days, and all 4 with no fluorescence at 5 minutes underwent revision amputation. The dual-threshold rule yielded sensitivity of 1.00 (95% confidence interval, 0.84-1.00) and specificity of 0.78 (95% confidence interval, 0.40-0.97).

A locked, 6-minute indocyanine green protocol with arrival-within-3-minute and clearance-by-5-minute thresholds converted equivocal signs into actionable hemodynamics. Within this cohort, the prespecified temporal rule separated survivors from failures and consistently exposed reversible congestion. The workflow was feasible in this single-center cohort and warrants device-agnostic external validation against expert clinical judgment across imaging platforms.