Fluid management in septic acute kidney injury and cardiorenal syndromes

Intravenous fluids are commonly administered to patients with developing septic acute kidney injury (AKI). Conversely, fluids are just as commonly removed with diuretics or renal replacement therapy (RRT) techniques or ultrafiltration in patients with cardiorenal syndromes (CRS). In both groups, there is controversy regarding fluid management. However, in patients with septic AKI, the deleterious consequences of overzealous fluid therapy are increasingly being recognized, while concerns exist both about the possible adverse effects of excessive and/or insufficient fluid removal with diuretics or ultrafiltration in CRS. In this article, we discuss how interstitial edema can further delay renal recovery and why conservative fluid strategies are now being advocated in septic AKI. In patients with septic AKI, this strategy might require RRT to be given earlier to assist with fluid removal. However, in patients with either septic AKI or CRS, hypovolemia and renal hypoperfusion can occur if excessive fluid removal is pursued with diuretics or extracorporeal therapy. Thus, accurate assessment of fluid status and careful definition of targets are needed to improve clinical outcomes. Controlled studies of conservative versus liberal fluid management in patients with AKI or CRS seem justified.