Lymph Flow Before and After Lymphaticovenous Anastomosis Measured Using Transonic Transit-Time Ultrasound Microvascular Flowprobe

Background: Assessment of lymph flow has proven challenging. Transit-time ultrasound technique (TTUT) is the first technique that provides real-time quantitative lymphatic flow values. In cardiothoracic surgery and neurosurgery, this technique has tremendous clinical value in assessing surgery quality and predicting outcomes. The objective of this study was to measure lymph flow before and after lymphaticovenous anastomosis (LVA), using TTUT. Methods and Results: Consecutive patients with peripheral lymphedema undergoing LVA were included. Preoperative workup was performed using indocyanine green (ICG) lymphangiography. Perioperatively, the Transonic^® Microvascular Flowprobe was used to measure lymph flow before and after anastomosis. Twenty-five patients with International Society of Lymphology stage IIA (68%) and stage IIB (32%) peripheral lymphedema were included. Lymph flow velocities ranged from 0.02 to 0.80 mL/min (mean 0.25 ± 0.19) before anastomosis and from 0.02 to 0.86 mL/min (mean 0.27 ± 0.22) after anastomosis (p = 0.340). Mean flow values were significantly higher in the upper extremities compared with the lower extremities. Furthermore, there was a decrease in flow in patients with ICG stage IV in comparison with ICG stage III. Clinical outcomes could not be directly correlated with flow values in these individual cases. Conclusion: TTUT micro-flowprobe is a suitable instrument to measure real-time quantitative lymphatic flow in both lymphatics and LVA. It can confirm patency of lymphatic collectors and LVA peroperatively. Significantly higher lymph flow velocities were found in upper extremities in comparison with lower extremities, both before and after LVA. Further studies should be performed to evaluate lymph flow values and clinical correlation.