(CS-139) The Use of Near-infrared Spectroscopy in Assessment of Viability and Monitoring of Healing Trajectories in Traumatic Flaps

Charles Andersen, MD, FACS, MAPWCA

Introduction: Reliable methods of assessing flap viability beyond visual inspection would conserve tissue flaps and improve outcomes. Near-infrared spectroscopy is a non-invasive, non-contact way of assessing oxygenation and perfusion status of superficial tissue.

The objectives of this study were to: 1) determine the viable cross-sectional flap area in jeopardized flaps using near-infrared spectroscopy, and 2) determine the average time to heal with conserved flaps compared to historical data.

Methods: This was a single center prospective cohort study performed at Madigan Army Medical Center between June 2023 and July 2024. Tissue flaps were assessed for viability using near-infrared spectroscopy to conserve cross sectional area instead of discarding the whole flap. Tissue exhibiting deoxyhemoglobin values equal to or exceeding 0.5 were deemed non-viable and sharply debrided to prevent infection risk. Any tissue exhibiting StO₂ values equal to or exceeding 50% were deemed viable and were approximated to normal anatomical position to continue monitoring at subsequent visits. Reductions in wound sizes and time to heal were recorded.

Results: The median wound cross-sectional area without the preserved flap (9.1 [4.2, 11.7] cm²) was larger than with the preserved flap (1.6 [0.9, 2.9] cm²; P = 0.0001). The median time to heal with preserved flaps was 22 [21, 41] days compared to 28-42 days in the literature (P = 0.82).

Discussion: Preservation of traumatic flaps significantly reduced cross-sectional wound areas while protecting against infection, providing tensile strength, and reducing the amount of re-epithelialization required for wound closure. Times to heal were reduced by ~1 week when preserved flaps were used compared to average times to heal within the literature. Near-infrared spectroscopy was a significant aid in determining viability of flap tissue that allowed the preservation of tissue and reduced healing times. Clinical standards should be updated to utilize NIRS or other modalities to assess tissue viability and thereby preserve tissue and reduce time to heal in patients with wounds.