Acute kidney injury

Acute kidney injury (AKI) is serious complication of critical illness in general and a major complication of acute decompensated heart failure (ADHF), acute coronary syndromes (ACS), cardiac surgery, and radiocontrast administration in particular. New consensus definitions of this syndrome have enabled a more detailed understanding of its epidemiology. Some degree of AKI is seen in up to 60% of critically ill patients, depending on the characteristics of the population of critically ill patients being studied, and its development is independently associated with an increased risk of death. Its pathogenesis is complex and probably changes according to the aetiology of the underlying condition. However, in most conditions, it is likely that neurohumoral factors, haemodynamic factors, and immunological/inflammatory processes all play important roles in its development. Prevention of AKI requires attention to general patient care, prompt resuscitation, avoidance of excessive fluid administration, maintenance of an adequate cardiac output, maintenance of an adequate mean arterial pressure, avoidance of a markedly raised right atrial pressure, avoidance of intravascular volume depletion, maintenance of an adequate haemoglobin, and avoidance of nephrotoxins. No pharmacological agents have been shown to be consistently effective as preventive agents. If AKI is severe enough to require the application of renal replacement therapy, several dialytic techniques are now available to support patients to recovery, if the primary disease can be effectively treated. Worldwide, continuous renal replacement therapy (CRRT) is now more commonly used than intermittent dialysis, while peritoneal dialysis is all but absent from the treatment of adult patients with severe AKI. The advantages of CRRT (gentle and steady fluid removal, haemodynamic stability, steady acid–base control) are particularly important in critically ill patients and in patients with myocardial dysfunction. However, no sufficiently powered studies have yet demonstrated that one technique is superior to another in terms of outcome. Once AKI has become severe enough to require CRRT, no pharmacological agents have been consistently shown to accelerate recovery. The prognosis of AKI requiring renal replacement therapy remains unfavourable in up to 50% of patients, mostly because of the underlying disease.