Strategies for Preventing Acute Kidney Injury
SAN DIEGO—The incidence of acute kidney injury (AKI) is high and climbing, according to a presenter at the Society for Critical Care Medicine 2011 annual meeting.
Sean Bagshaw, MD, MSc, Assistant Professor of Critical Care Medicine and Assistant Professor at the School of Public Health at the University of Alberta in Edmonton, stressed the importance of early identification of at-risk patients and of primary and secondary prevention to head off the 50-60% mortality rate associated with AKI in critical illness.
“While there are very few context-specific interventions available, all patients should be appropriately resuscitated from a systemic/renal hemodynamic point of view,” Dr. Bagshaw told Renal & Urology News.
Dr. Bagshaw led a study showing that the incidence of AKI increased by 2.8% per year between 1996 and 2005 (Crit Care. 2007;11:R68). The same trend has been observed by researchers in the United States.
The tools for identifying AKI are imprecise and the cause of AKI is multifactorial and may include septic shock, adverse sequelae of major surgery, or medications. Consequently, optimizing systemic and kidney perfusion are the main and only proven primary prevention strategies, he noted.
The pharmacologic tools for renal hemodynamic optimization in septic AKI include optimizing cardiac output, mean arterial pressure and renovascular blood flow with targeted fluid therapy and inotropes. Early use of appropriate antimicrobial therapy has been shown to be effective. Preliminary evidence indicates fenoldopam and erythropoietin also may improve have a role in prevention of AKI, however, further confirmatory study is needed.
In cardiac-surgery-associated AKI, available evidence provides an unclear picture. For example, some studies have shown that preoperative statin therapy improves outcomes, whereas the Cardiopulmonary bypass, REnal injury and Atorvastatin (CREAT) pilot randomized trial comparing atorvastatin versus placebo, showed no benefit to their peri-operative use to prevent post-operative AKI (Prowle et al. Presented as an abstract at the 2010 congress of the European Society of Intensive Care Medicine) Off-pump bypass surgery appears to be renoprotective, as does sodium bicarbonate. Nesiritide is another possible candidate.
Three theoretical pathophysiology-based interventional approaches to prevention of contrast-induced AKI are induction of a forced diuresis and production of high urine-flow rates; induction of renal vasodilatation; and attenuation of oxidative stress and inflammation, Dr. Bagshaw said. Risk identification is critical, he noted. Approaches that appear to be effective in preventing contrast-induced AKI include the use of hydration, sodium bicarbonate, and N-acetylcysteine.
Chirag Parikh, MD, senior author of a systematic review of prevention and treatment of AKI in patients undergoing cardiac surgery (Am J Nephrol 2010;31:408-418), said he agrees with the concepts presented by Dr. Bagshaw. “However there's still the need for better information in this field,” said Dr. Parikh, Associate Professor of Internal Medicine, Yale University School of Medicine, New Haven, Conn. “We are thinking of conducting an AKI-prevention study in the ICU setting to help determine whether promising interventions reliably reduce rates of dialysis and mortality in this setting.”
Matthew James, MD, of the Department of Medicine and Department of Community Health Sciences, University of Calgary, Alberta, agreed that AKI prevention is extremely important. “Early resuscitation and treatment of sepsis, as discussed by Dr. Bagshaw, are valuable examples of important interventions that prevent AKI and improve clinical outcomes in critical illness,” Dr. James said. “New agents to prevent AKI need further evaluation in trials to determine if they improve survival and prevent end-stage renal disease.”