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KEY POINTS
The main goals of renal replacement therapy (RRT) for acute kidney injury (AKI) are to provide solute clearance and homeostasis (electrolytes, acid–base, and volume status), while personalizing renal support to facilitate other aspects of care of the critically ill patient (fluid balance, nutritional support, etc.).
Indications for initiation of RRT for AKI should be conservative; in the absence of emergency indications, a strategy of watchful waiting should be taken.
In the setting of AKI, no specific RRT modality provides a proven mortality benefit over another. However, specific clinical scenarios (e.g., acute liver failure, increased intracranial pressure, severe hemodynamic instability) may mandate a particular approach.
In the setting of AKI, a minimum dose of 20 to 25 mL/kg/h of continuous renal replacement therapy (CRRT) should be delivered. Data on dosing of intermittent dialysis suggest prescription of a minimum Kt/Vurea of 1.2 per treatment three times a week. Additional treatments may be required for volume control or inadequate solute clearance.
Regarding anticoagulation to maintain the extracorporeal circuit function, options include heparin, citrate, and no anticoagulation. Each has its own risks and benefits. In continuous modalities, citrate is associated with longer filter lifespan.
In the setting of AKI requiring RRT, nutritional support for proteins and energy should follow the current ASPEN guidelines. For micronutrients and vitamins, data are lacking to recommend a particular approach.
Depending on the modality and intensity of RRT, dosing strategies for medications (including antimicrobials) differ significantly. Adherence to dosing guidelines ensures that the targeted therapeutic dose is delivered, as inappropriate dosing has a significant impact on patient outcomes and increases the risk of mortality.
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In the absence of specific therapies to prevent or treat acute kidney injury (AKI), care is mainly supportive, including treatment of the underlying disease state, conservative management of uremic complications (hyperkalemia, metabolic acidosis, volume overload) and, when needed, renal replacement therapy (RRT). Around 5% of all patients admitted with AKI will receive a form of RRT.1 Over the last decade, there have been considerable advances in our understanding of dosing and timing of acute RRT, but many aspects of RRT are still not supported by evidence from randomized controlled trials (RCTs).2 Unlike patients with end-stage renal disease (ESRD), many surviving patients with AKI treated with RRT will recover kidney function. To maximize the chance of survival and recovery of kidney function, clinicians should prescribe RRT in the ICU to optimize timing of initiation, modality choice, dosage, and avoidance of complications.
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RRT: AN INTRODUCTION TO CLEARANCE
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RRT refers to the use of extracorporeal support to remove solutes and water. The currently available modalities include intermittent hemodialysis (IHD), continuous renal replacement therapy (CRRT), prolonged intermittent renal replacement therapy (PIRRT), and peritoneal dialysis (PD). Advances in technology with readily available large-bore venous catheters and efficient blood pumps have made arteriovenous circuits such as continuous ...