The International Journal of Artificial Organs

The Acute Dialysis Quality Initiative (ADQI) is an ongoing process that seeks to produce evidence-based recommendations for the prevention and management of acute kidney injury (AKI) and on different issues concerning acute dialysis. Our methods involve a combination of both expert panel and evidence appraisal, and this approach was chosen to achieve the best of both options. This approach has led to important practice guidelines with wide acceptance and adoption into clinical practice. We further recognize that additional research will be needed and have proposed specific studies that will help move this field forward.

Fluids are the only known method of attenuating renal injury. Furthermore, whether for hydration, resuscitation or renal replacement therapy, fluid prescriptions must be tailored to the fluid and electrolyte, cardiovascular status and residual renal function of the patient. Different fluids have significantly different effects both on volume expansion as well as on the electrolyte and acid-base balance; while controversial, different fluids may even influence renal function differently. This systematic review focuses on fluids for prevention and management of acute kidney injury. We have reviewed the available evidence and have made recommendations for clinical practice and future studies.

Volume management is an integral component of the care of patients with acute kidney injury (AKI). Considerable controversy exists regarding the use of pharmacological agents for volume management. Although overt fluid overload is often seen in AKI and may prompt attention for the use of diuretics, often these agents are used in the absence of fluid retention. Over the last decade several new agents have become available for volume removal. We reviewed the literature on this topic and addressed four key questions for the appropriate utilization of these agents. These include the drug targets and mechanism of action of available agents; clinical goals and criteria for timing of intervention; adaptation of therapy for specific clinical settings and measures required for monitoring effectiveness and patient safety. This report details our current knowledge in this area, provides evidence-based clinical practice recommendations where appropriate, and formulates a research agenda to address unanswered questions. (Int J Artif Organs 2008; 31: 127–44)

Management of fluid balance is one of the basic but vital tasks in the care of critically ill patients. Hypovolemia results in a decrease in cardiac output and tissue perfusion and may lead to progressive multiple organ dysfunction, including the development of acute renal injury (AKI). However, in an effort to reverse pre-renal oliguria, it is not uncommon for patients with established oliguric acute renal failure, particularly when associated with sepsis, to receive excessive fluid resuscitation, leading to fluid overload. In patients with established oliguria, renal replacement therapy may be required to treat hypervolemia. Safe prescription of fluid loss during RRT requires intimate knowledge of the patient's underlying condition, understanding of the process of ultrafiltration and close monitoring of the patient's cardiovascular response to fluid removal. To preserve tissue perfusion in patients with AKI, it is important that RRT be prescribed in a way that optimizes fluid balance by removing fluid without compromising the effective circulating fluid volume. In patients who are clinically fluid overloaded, it is equally important that the amount of fluid removed be as exact as possible. Fluid balance errors can occur as a result of inappropriate prescription, operator error or machine error. Some CRRT machines have potential for significant fluid errors if alarms can be overridden. Threshold values for fluid balance error have been developed which can be used to predict the severity of harm. It is important that RRT education programs emphasize the risk associated with fluid balance errors and with overriding machine alarms.

Cardiac surgery associated acute kidney injury (CSA-AKI) is a significant clinical problem. Its pathogenesis is complex and multifactorial. It likely involved at least six major injury pathways: exogenous and endogenous toxins, metabolic factors, ischemia and reperfusion, neurohormonal activation, inflammation and oxidative stress. These mechanisms of injury are likely to be active at different times with different intensity and probably act synergistically. Because of such complexity and the small number of randomised controlled investigations in this field only limited recommendations can be made. Nonetheless, it appears important to avoid nephrotoxic drugs and desirable to avoid hyperglycemia in the peri-operative period. The duration of cardiopulmonary bypass should be limited whenever possible. Off-pump surgery, when indicated, may decrease the risk of AKI. Invasive hemodynamic monitoring focussed on attention to maintaining euvolemia, an adequate cardiac output and an adequate arterial blood pressure is desirable. Echocardiography may be useful in minimizing atheroembolic complications. The administration of N-acetylcysteine to protect the kidney from oxidative stress is not recommended. There is marked lack of randomised controlled trials in this field.

Numerous strategies have been evaluated to prevent early CSA-AKI. Although correction of hemodynamic problems is paramount, there are no clinical studies that compare different hemodynamic management or monitoring strategies with regard to their effect on kidney function. Pharmacologic strategies including diuretics, different classes of vasodilators and drugs with anti-inflammatory effects such as N-acetyl-cysteine, do not appear to be effective. Most of the studies are underpowered and use physiological rather than clinical endpoints. Further trials are warranted with fenoldopam and nesiritide (rhBNP). Observational and underpowered randomized studies show beneficial renal effects of off-pump technique and avoidance of aortic manipulation. There is very limited evidence for preoperative fluid loading and preemptive RRT. Potentially nephrotoxic agents should be used with caution in patients at risk of CSA-AKI. Tranexamic acid or aminocaproic acid should be preferred over aprotinin. No pharmacologic intervention has been adequately tested in the prevention of late CSA-AKI. A single-center study, including a predominance of patients after cardiac surgery, showed a decrease of kidney injury with tight glycemic control.

Members of the Acute Dialysis Quality Initiative (ADQI) participated in a 3-day conference in Vicenza in May 2007 to evaluate the available literature on this topic and draft consensus recommendations for research studies in this area. This report summarizes the available evidence and describes the key questions that will need to be addressed with the goal of standardizing the care of patients with cardiac surgery-associated acute kidney injury (CSA-AKI) and improving outcomes.