Renal replacement therapy (RRT) is one of the most expensive interventions used in an already cost burdensome intensive care unit (ICU) setting. Prescribing RRT in the critically ill is complex and ideally should involve clear communication between nephrologist and intensivist.
RRT modalities include peritoneal dialysis, intermittent hemodialysis, continuous renal replacement therapies, and sustained low-efficiency daily dialysis.
These modalities utilize 2 transport mechanisms in providing renal replacement: diffusion and convection. These forces result in solute clearance and plasma water removal or ultrafiltration (UF).
RRT is initiated early in patients whose renal function is not expected to quickly improve due to severity of illness and is unresponsive to resuscitation: multiorgan failure, high fractional excretion of sodium (FENa), rising azotemia (without plateau of urea or creatinine levels), and oliguria all suggestive of acute tubular necrosis (ATN).
At present, randomized trials and meta-analyses, do not support a mortality benefit for one modality over another. However, a gradual clearance rate may be wise in hemodynamic instability, acute coronary syndromes, elevated intracranial pressures (ICPs), or hypo/hypernatremia.
Almost 60 years ago, RRT was first used to treat acute kidney injury (AKI) during the Korean War.1 Within 25 years, continuous therapies were first attempted in Germany.2 RRT modalities have since expanded, becoming commonplace in most hospitals of the developed world. In AKI, when preventative and supportive management fails we turn to RRT.
In the past decade, admissions for AKI increased with a doubling in the incidence of severe AKI (Figure 31–1).3 In parallel, approximately 200,000 patients required RRT in 2012.3 The incidence of RRT-requiring AKI now surpasses that of end-stage renal disease (ESRD).4 What's more, the morbidity and mortality of AKI requiring RRT extends beyond hospitalization.3,5
Population incidence of dialysis-requiring acute kidney injury (AKI) in the United States from 2000 to 2009 (count and incidence rate per million person-years). I bars represent 95% confidence intervals (CIs). The number of cases of dialysis-requiring AKI increased from 63,000 (2000) to almost 164,000 (2009); population incidence increased 10% per year from 222 to 533 cases/million person-years.3 (Reproduced with permission from Hsu RK, McCulloch CE, Dudley RA, et al: Temporal Changes in Incidence of Dialysis-Requiring AKI, J Am Soc Nephrol 2013 Jan: 24(1):37-42.)
The necessity for RRT in the ICU arises in 1 of 3 clinical situations: AKI, critically ill ESRD patients,6 and drug or toxic overdoses. RRT for AKI is dramatic but less common than most think. The incidence of AKI in the ICU is relatively low between 6% and 19%, but can be higher depending on population studied and risk, injury, failure loss, and end-stage kidney disease (RIFLE) criteria.7,8 RRT needs occur in up to 5% of AKI....