The future of free flap monitoring by laser continuous doppler flowmetry: A prospective assessment in consecutive 71 patients

Objective: This study evaluated the effectiveness of laser Doppler flowmetry (LDF) in detecting perfusion disturbances during microvascular free tissue transfer. Methods: Conducted at a single centre from December 2020 to September 2022, this prospective study involved 71 patients mainly undergoing head and neck free flap reconstructions, using the Pocket LDF™ for continuous perfusion monitoring. Results: Out of the 71 cases, data from 69 cases were analysed after excluding those with significant noise or sensor detachment. Blood flow disturbances were observed in 9 cases (13.0 %), with 5 of these cases with a history of surgery or radiation in the same area. There were 5 cases of ischaemia, 4 of which occurred during monitoring. There were 4 cases of venous congestion, with 1 occurring during monitoring. Re-operation was necessary in 8 cases (11.6 %), involving flap replacements, vascular re-anastomoses and hematoma evacuation. Complete flap necrosis occurred in 5 cases (7.2 %) and partial necrosis occurred in 3 cases (4.3 %). The LDF device demonstrated the ability to identify perfusion issues hours before the clinical symptoms manifested, suggesting its potential for early intervention. However, challenges included maintaining continuous monitoring immediately post-surgery and during patient transfers. Conclusion: LDF is a valuable, non-invasive tool for early detection of perfusion disturbances in free flap procedures. It provides continuous, real-time feedback on microcirculation, facilitating timely interventions. Despite its benefits, enhancements in sensor adhesion and wireless technology are needed to improve monitoring reliability. Further studies are recommended to refine LDF usage and validate its efficacy in various clinical settings.