Improving intraoperative perfusion reliability in anterolateral thigh free flap reconstruction for diabetic foot ulcers

Figure 1 Improving anterolateral thigh free-flap perfusion reliability in diabetic foot ulcers. This schematic frames anterolateral thigh (ALT) free-flap perfusion in diabetic foot ulcer (DFU) as an integrated continuum linking systemic modifiable physiology - glycemic status [hemoglobin A1c (HbA1c)/perioperative glucose], anemia/iron status, respiration and oxygen delivery (DO₂) [arterial partial pressure of carbon dioxide/oxygen (PaCO₂/PaO₂), ventilation], and nutritional reserve (albumin/prealbumin) - to regional vascular capacity in the setting of diabetes-related medial arterial calcification (MAC), where ankle-brachial index (ABI) may be misleading, and distal perfusion should be characterized using toe pressure/toe-brachial index (TBI), skin perfusion pressure (SPP), and transcutaneous oxygen tension (TcPO₂), with revascularization when indicated. These layers converge with microcirculatory dysfunction and impaired capillary recruitment at the flap and recipient-site level (conceptual note: “Brightness ≠ exchange efficiency”). The central intraoperative quantitative perfusion decision hub integrates systemic status, distal perfusion context, and standardized indocyanine green fluorescence angiography (ICG-FA) acquisition, emphasizing fluorescence-time curve kinetics [wash-in slope, time to maximum intensity, maximum fluorescence intensity, area under the curve (AUC)] rather than single intensity snapshots. Outputs are actionable intraoperative strategies (revise anastomosis, trim hypoperfused margins, supercharging/additional venous outflow, proceed vs delay/optimize) to reduce partial/total necrosis and reoperation and improve limb salvage. ROI: Region of interest.