Design strategies for Near-Infrared Spectroscopy (NIRS) devices in Deep Inferior Epigastric Perforator (DIEP) flaps: A Narrative Review

Background: Near-Infrared Spectroscopy (NIRS) is a non-invasive, continuous monitoring technique that shows potential for assessing tissue oxygenation and detecting vascular compromise in free Deep Inferior Epigastric Perforator (DIEP) flaps. Despite demonstrated clinical benefits, current NIRS devices exhibit limitations related to probe attachment efficiency, patient mobility, and adaptability to breast anatomy. This narrative review provides a comprehensive overview of current landscape of NIRS devices and other optical monitoring systems with comparable attachment requirements. It aims to identify design strategies to optimize NIRS probes for free DIEP flaps, focusing on geometric design, materials, and adhesives. Methods: A literature search across Medline, Embase, Web of Science, Scopus, Google Scholar was performed following PRISMA guidelines. Articles and patents were screened to assess device designs characteristics, including geometry, materials, and adhesive strategies, for both commercially available and custom-made devices. Data extraction focused on design-relevant features rather than clinical performance metrics. Results: Thirteen commercial NIRS devices were identified, primarily relying on wired, rectangular or elliptical probes with soft-foam or flexible plastic housings and self-adhesive layers. Additional transparent dressings are frequently required to enhance fixation and reduce ambient light interference. Nine custom-made devices demonstrated greater design variability, including wireless systems, 3D-printed housings, and flexible materials such as gradient cross-linked silicone polymers. Adhesive strategies vary widely, from medical-grade acrylic and hydrocolloid adhesives to sutures and transparent dressings. Only a limited number of designs meet the specific challenges of curved breast anatomy and small flap dimensions. Conclusion: Optimizing NIRS devices for DIEP flaps requires compact, flexible, and wireless designs combined with reliable, non-obstructive adhesive solutions to ensure clinical-grade signal quality, patient comfort and wearability. While commercial devices face limitations in wireless functionality, custom-made devices show promise in material flexibility and wireless design, though scalability challenges persist. Further research should validate these innovations for clinical use and scalable manufacturing.