The renal microcirculation and biomarkers in acute kidney injury of ICU patients

Acute kidney injury is related with a high mortality rate in hospitalized and critically ill patients. The need for immediate recognition and management of acute kidney injury highlights the importance of the underlying pathophysiological mechanisms understanding as well as of early diagnosis. The role of the renal microcirculation in acute kidney injury through the interlinked occurrence of renal hypoxia and activation of inflammatory pathways is well documented. Endothelial damage and disruption of the balance between nitric oxide (NO) and reactive oxygen species result in deterioration of renal hypoxia at the microcirculatory level. The assessment and imaging of the renal microcirculation could provide useful information about the pathophysiology of acute kidney injury; microcirculatory changes are described in both the initiation and expansion of tubular injury. Preventive and therapeutic measures should be based on the early recognition of kidney damage and restoration of the balance between kidney oxygenation, endothelium, NO and reactive oxygen species. This is a review of the role of the microcirculation in the development and extension of acute kidney injury in relation with renal hypoxia and activation of the inflammatory pathways, and of the new biomarkers used for early diagnosis and prognosis of acute kidney injury.