BACKGROUND: Hypotension during dialysis arises from vasomotor tone alterations and hypovolemia, with disrupted counterregulatory mechanisms in acute kidney injury (AKI) patients. This study investigated the predictive value of preload dependency, assessed by the passive leg raising (PLR) test, and arterial tone, measured by dynamic elastance (Eadyn), for intradialytic hypotension (IDH). METHODS: In this prospective observational study conducted in a tertiary hospital ICU, hemodynamic parameters were collected from critically ill AKI patients undergoing intermittent hemodialysis using the FloTrac/Vigileo system. Baseline measurements were recorded before KRT initiation, including the PLR test and Eadyn calculation. IDH was defined as mean arterial pressure (MAP) < 65 mmHg during dialysis. Logistic regression was used to identify predictors of IDH, and Kaplan-Meier analysis assessed 90-day survival. RESULTS: Of 187 patients, 27.3% experienced IDH. Preload dependency, identified by positive PLR test, was significantly associated with IDH (OR 8.54, 95% CI 5.25-27.74), while baseline Eadyn was not predictive of IDH in this cohort. Other significant predictors of IDH included norepinephrine use (OR 16.35, 95% CI 3.87-68.98) and lower baseline MAP (OR 0.96, 95% CI 0.94-1.00). IDH and a positive PLR test were associated with lower 90-day survival (p < 0.001). CONCLUSIONS: The PLR test is a valuable tool for predicting IDH in critically ill AKI patients undergoing KRT, while baseline Eadyn did not demonstrate predictive value in this setting. Continuous hemodynamic monitoring, including assessment of preload dependency, may optimize patient management and potentially improve outcomes. Further research is warranted to validate these findings and develop targeted interventions to prevent IDH.