Predictive vs. Flow-Derived Haemodynamic Monitoring in Major Abdominal Surgery: Associations with Intraoperative Hypotension and Postoperative Outcomes.

Introduction: Intraoperative hypotension (IOH) is a frequent manifestation of haemodynamic instability during general anaesthesia. Advances in arterial waveform analysis have led to two distinct monitoring strategies: flow-derived platforms and predictive algorithms designed to anticipate hypotension. However, prospective comparisons and their associations with IOH and postoperative outcomes remain limited. The objective was to compare predictive haemodynamic monitoring using the Hypotension Prediction Index (HPI) with flow-derived monitoring using the Vigileo/FloTrac system and to evaluate their associations with IOH and postoperative outcomes. Methods: In this single-center prospective observational study, 101 adults undergoing elective major abdominal surgery under general anaesthesia were monitored using either the HPI system (n = 49) or the Vigileo/FloTrac system (n = 52). Primary outcomes were cumulative duration and frequency of IOH (mean arterial pressure < 65 mmHg). Secondary outcomes included postoperative complications, organ injury biomarkers (troponin, creatinine, eGFR), and hospital length of stay. Multivariable regression models adjusted for predefined confounders were used to estimate associations. Results: Vigileo/FloTrac monitoring, compared with HPI, was independently associated with a greater cumulative duration of IOH (adjusted β = 1.66; 95% CI, 0.63-2.72) and a higher number of hypotensive episodes (adjusted β = 0.53; 95% CI, 0.10-0.95). Monitoring strategy was not associated with surgical site, respiratory, or neurological complications. However, Vigileo/FloTrac monitoring was associated with higher odds of vascular complications (adjusted OR = 4.36; 95% CI, 1.13-20.41). No significant associations were observed between monitoring strategy and postoperative organ injury biomarkers or length of hospital stay. Conclusions: Predictive haemodynamic monitoring using the HPI system was associated with lower IOH burden compared with the Vigileo/FloTrac system. However, these differences were not consistently accompanied by improvements in postoperative outcomes. Haemodynamic optimisation should be considered as one component within a broader, integrated perioperative management strategy. Further large-scale, multicenter prospective studies are warranted to clarify its impact on patient-centered outcomes.