Septic acute kidney injury: hemodynamic syndrome, inflammatory disorder, or both?

Septic acute kidney injury (S-AKI) is the most common cause of kidney injury in the ICU. Decreased renal blood flow and inflammation have both been suggested as mechanisms of S-AKI. Benes and colleagues present a study of S-AKI in which sepsis is induced by fecal peritonitis and bacterial infusion. In this study, although decreased renal blood flow and increased renal vascular resistance were present in some of the animals that developed S-AKI, inflammatory activation without decreased renal blood flow and increased renal vascular resistance was seen in other animals. Systemic hemodynamic findings provided little information on renal hemodynamics or risk of S-AKI. The study highlights the extraordinary complexity of S-AKI and the need for clinicians to recognize our limited understanding of its pathogenesis and the weakness of the decreased perfusion paradigm as the sole explanation for the loss of renal function seen in severe sepsis.