Technical feasibility of synchronized multispectral dual-site optical sensing during vascular occlusion in an acute porcine flap model

This study evaluated the feasibility of FlapSense, a multispectral dual-site optical patch designed to acquire synchronized optical signals from an elevated flap and adjacent healthy tissue during controlled arterial and venous occlusion. An in vivo porcine abdominal flap model was used in four animals. The FlapSense device was positioned with one sensing region over the flap and another over adjacent healthy tissue. Arterial and venous occlusion was performed by clamping the cranial epigastric artery and veins while collecting optical data from the FlapSense device and a reference device, Hutchinson InSpectra, simultaneously from both regions. Baseline-relative oxygenation (HbD) and relative total hemoglobin (HbT) indices were calculated using the modified Beer-Lambert Law from five wavelengths. Out of four animals, post-experiment inspection identified residual vascular and deep-tissue connections in two animals, indicating incomplete vascular isolation. These animals were excluded post hoc from the occlusion-response analysis. The analysis included five arterial clamp cycles and six venous clamp cycles from two animals. Across the analyzed sections, flap-side HbD showed clamp-associated waveform similarity with InSpectra $$StO_2$$ in Pig 1 and during the venous cycles in Pig 2, whereas the Pig 2 arterial cycles did not show positive correspondence. Flap-side HbT showed event-associated changes but diverged in direction from InSpectra THI during several venous clamp periods. Flap-side optical changes were larger than healthy-side changes, supporting localization of the occlusion-associated response to the flap-sensing region. These data support architecture and acquisition feasibility but do not validate postoperative monitoring performance or healthy-site correction, and complete vascular isolation during clamping was not confirmed. Overall, FlapSense supported synchronized dual-site optical acquisition and captured baseline-relative occlusion-associated optical changes during controlled vascular occlusion.