The Dynamic Changes in Hemodynamics of the Forehead Flap During Tissue Expansion

Background: The tissue expansion process brings changes in hemodynamics. Objective: To measure the change in vessel diameter, blood flow, and resistance in the blood vessels using ultrasound before, during, and after tissue expansion. Methods: Patients undergoing the embedment of a forehead expander from September 2021 to October 2022 were included. Hemodynamics parameters, including vessel diameter, blood flow velocity, and resistance index (RI) of the supraorbital artery (SOA), supratrochlear artery (STrA), and frontal branch of the superficial temporal artery (FBSTA), were measured with ultrasound before and 1, 2, 3, and 4 months after expansion. Results: Nine males and six females with ages ranging from 15 to 26 years (mean, 20 years) were included. After 4 months of expansion, the diameter of the STrA, SOA, and FBSTA increased significantly, the RI decreased significantly, and except the right SOA, peak systolic flow velocity increased significantly. Conclusion: The parameters of flap perfusion were significantly improved in the first 2 months of expansion and tended to stable values.