Intraoperative hypotension and postoperative acute kidney injury: Evidence and controversies

Acute kidney injury (AKI) remains one of the most common serious complications after noncardiac surgery, and intraoperative hypotension (IOH) is consistently identified as a modifiable risk factor. Observational studies show a consistent, roughly dose-response association between IOH, particularly at mean arterial pressures below 60-65 mmHg, and postoperative AKI, with stronger associations in patients with limited renal reserve. Definitions of IOH vary widely, which complicates the comparison of studies and the translation of thresholds into clinical targets. Randomized trials of individualized or higher blood pressure targets have generally not confirmed a kidney-protective benefit, and pooled analyses with trial sequential analysis have not demonstrated that higher targets reduce AKI. This narrative review examines how IOH definitions evolved, summarizes the conflicting intervention evidence, and assesses the controversies that shape current practice. The review concludes that avoiding severe and sustained hypotension remains reasonable, whereas current randomized trial evidence does not support a general kidney-protective benefit of higher or individualized blood pressure targets. This conclusion is provisional and is tempered by the methodologic and causal uncertainties.