Acute kidney injury in the critically ill patient

The stage at which acute kidney injury (AKI) is detected is dependent upon the definition used. More recently it has been demonstrated that even relatively small increments of serum creatinine portend a worse outcome. This has prompted the development of new definitions based on small rises in serum creatinine or decreases in urine output. Acute kidney injury on the intensive care unit (ICU) is usually multifactorial secondary to hypovolaemia and sepsis resulting in hypoperfusion of the kidneys. In patients with good baseline kidney function the condition is generally reversible if the patient regains health. However it has been recognised that kidney function does not always completely recover. An episode of AKI may represent an antecedent to the development of chronic kidney disease (CKD), and patients who already have CKD are at risk of AKI and further loss of function. Preventative measures should therefore be instituted as soon as possible in patients identified to be at risk of developing AKI. The cornerstone of treatment for patients who develop AKI remains renal replacement therapy (RRT). Ultimately it is hoped that the development of new biomarkers may enable earlier detection of patients at risk of developing AKI.