Hemodynamic Instability during Acute Kidney Injury and Acute Renal Replacement Therapy: Pathophysiology and Clinical Implications

Hemodynamic instability associated with acute renal replacement therapy (aRRT, HIRRT) and/or with acute kidney injury (AKI) is frequently observed in the intensive care unit; it affects patients' renal recovery, and negatively impacts short- and long-term mortality. A thorough understanding of mechanisms underlying HIRRT and AKI-related hemodynamic instability may allow the physician in adopting adequate strategies to prevent their occurrence and reduce their negative consequences. The aim of this review is to summarize the main alterations occurring in patients with AKI and/or requiring aRRT of those homeostatic mechanisms which regulate hemodynamics and oxygen delivery. In particular, a pathophysiological approach has been used to describe the maladaptive interactions between cardiac output and systemic vascular resistance occurring in these patients and leading to hemodynamic instability. Finally, the potential positive effects of aRRT on these pathophysiological mechanisms and on restoring hemodynamic stability have been described.