Renal-Replacement Therapy in the Critically Ill — Does Timing Matter?

Acute kidney injury (AKI) is a common syndrome that is independently associated with increased mortality. A standardized definition is important to facilitate clinical care and research. The definition of AKI has evolved rapidly since 2004, with the introduction of the Risk, Injury, Failure, Loss, and End-stage renal disease (RIFLE), AKI Network (AKIN), and Kidney Disease Improving Global Outcomes (KDIGO) classifications. RIFLE was modified for pediatric use (pRIFLE). They were developed using both evidence and consensus. Small rises in serum creatinine are independently associated with increased mortality, and hence are incorporated into the current definition of AKI. The recent definition from the international KDIGO guideline merged RIFLE and AKIN. Systematic review has found that these definitions do not differ significantly in their performance. Health-care staff caring for children or adults should use standard criteria for AKI, such as the pRIFLE or KDIGO definitions, respectively. These efforts to standardize AKI definition are a substantial advance, although areas of uncertainty remain. The new definitions have enabled the use of electronic alerts to warn clinicians of possible AKI. Novel biomarkers may further refine the definition of AKI, but their use will need to produce tangible improvements in outcomes and cost effectiveness. Further developments in AKI definitions should be informed by research into their practical application across health-care providers. This review will discuss the definition of AKI and its use in practice for clinicians and laboratory scientists.

In patients with severe acute kidney injury (AKI) but no urgent indication for renal replacement therapy (RRT), the optimal time to initiate RRT remains controversial. While starting RRT preemptively may have benefits, this may expose patients to unnecessary RRT. To study this, we conducted a 12-center open-label pilot trial of critically ill adults with volume replete severe AKI. Patients were randomized to accelerated (12 h or less from eligibility) or standard RRT initiation. Outcomes were adherence to protocol-defined time windows for RRT initiation (primary), proportion of eligible patients enrolled, follow-up to 90 days, and safety in 101 fully eligible patients (57 with sepsis) with a mean age of 63 years. Median serum creatinine and urine output at enrollment were 268 micromoles/l and 356 ml per 24 h, respectively. In the accelerated arm, all patients commenced RRT and 45/48 did so within 12 h from eligibility (median 7.4 h). In the standard arm, 33 patients started RRT at a median of 31.6 h from eligibility, of which 19 did not receive RRT (6 died and 13 recovered kidney function). Clinical outcomes were available for all patients at 90 days following enrollment, with mortality 38% in the accelerated and 37% in the standard arm. Two surviving patients, both randomized to standard RRT initiation, were still RRT dependent at day 90. No safety signal was evident in either arm. Our findings can inform the design of a large-scale effectiveness randomized control trial.

Background One of the most dreaded complications of septic shock is acute kidney injury. It occurs in around 50% of patients, with a mortality rate of about 60% at 3 months. There is no consensus on the optimal time to initiate renal replacement therapy. Retrospective and observational studies suggest that early implementation of renal replacement therapy could improve the prognosis for these patients. Methods/design This protocol summarizes the rationale and design of a randomized, controlled, multicenter trial investigating the effect of early versus delayed renal replacement therapy in patients with severe acute kidney injury in early septic shock. In total, 864 critically ill adults with septic shock and evidence of acute kidney injury, defined as the failure stage of the RIFLE classification, will be enrolled. The primary outcome is mortality at 90 days. Secondary outcomes include safety, number of days free of mechanical ventilation, number of days free of renal replacement therapy, intensive care length of stay, in-hospital length of stay, quality of life as evaluated by the EQ-5D and renal replacement therapy dependence at hospital discharge. The primary analysis will be intention to treat. Recruitment started in March 2012 and will be completed by March 2015. Discussion This protocol for a randomized controlled study investigating the impact of the timing of renal replacement therapy initiation should provide an answer to a key question for the management of patients with acute kidney injury in the context of septic shock, for whom the mortality rate remains close to 60% despite improved understanding of physiopathology and recent therapeutic advances. Trial registration ClinicalTrials.gov identifier NCT01682590, registered on 10 September 2012.