This multicenter, prospective observational study aims to evaluate the predictive value of carotid corrected flow time (FTc) and peak flow velocity variability (PFVV) for hypotension during maintenance hemodialysis. Conducted at The First Affiliated Hospital of Wannan Medical College, Wuhu City Second People's Hospital, Wuhu Hospital of Chinese Traditional Medicine, Wuhu Jinghu District Hospital, and Wuhu Guangji Hospital, the study will include adult patients (≥18 years) with end-stage renal disease (ESRD) on long-term hemodialysis for at least three months. Patients with acute kidney injury, severe cardiac conditions, or other factors affecting results will be excluded. Ultrasound assessments of FTc and PFVV will be performed once, at 1 hour after dialysis initiation. Blood pressure will be monitored during the procedure. The primary outcome is to determine the sensitivity, specificity, and optimal cutoff points of FTc and PFVV in predicting intradialytic hypotension. The estimated sample size is 183 participants, with analysis performed using ROC curves and multivariate regression. The protocol complies with ethical standards and aims to develop a simple, non-invasive, real-time tool to improve patient safety and individualized management during hemodialysis.