Renal Replacement Therapy Initiation Indication (CRRT/RRT) — free guideline decision tool

Renal replacement therapy (RRT) initiation and modality decision in acute kidney injury, separating emergent indications from trend-based timing.

Any emergent indication (refractory hyperkalemia, severe acidosis pH < 7.1, refractory volume overload, uremic complications/severe azotemia, dialyzable poisoning) initiates RRT; without these, decide early vs late by trends. CRRT preferred when hemodynamically unstable/brain-injured.

Use to identify emergent RRT indications and to choose between continuous (CRRT) and intermittent (IHD) modalities based on hemodynamics.

Do not apply chronic-CKD BUN/creatinine thresholds to the critically ill; emergent indications and overall trajectory drive timing (original synthesis · not guideline verbatim). Trials of early vs delayed initiation (AKIKI, IDEAL-ICU, STARRT-AKI) have not shown consistent benefit to routine early start. CRRT offers smoother hemodynamics and ICP control; IHD corrects hyperkalemia faster in stable patients.

For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.

Inputs: Refractory hyperkalemia (K > 6.5 or rapidly rising, hard to control medically) No, Refractory severe metabolic acidosis (pH < 7.1) No, Refractory volume overload/pulmonary edema (diuretic-resistant) No, Uremic symptoms (encephalopathy/pericarditis/bleeding) or severe azotemia No, Dialyzable toxin/drug poisoning (e.g. lithium, methanol, ethylene glycol, salicylate) No, Hemodynamically unstable (needs vasopressors/brain injury/raised ICP) No → Result: RRT initiation No emergent indication（Determination: No emergent indication above: in the critically ill, do not wait for traditional CKD thresholds; decide early vs late initiation by volume/metabolic trends and overall clinical picture (evidence for early benefit is inconsistent), Modality choice: IHD or CRRT (IHD acceptable if hemodynamically stable; IHD is faster for rapid hyperkalemia correction), Management direction: Continue medical management (hyperkalemia, acidosis, volume), monitor urine output/electrolytes/acid-base and azotemia trends） Inputs: Refractory hyperkalemia (K > 6.5 or rapidly rising, hard to control medically) Yes, Refractory severe metabolic acidosis (pH < 7.1) Yes, Refractory volume overload/pulmonary edema (diuretic-resistant) Yes, Uremic symptoms (encephalopathy/pericarditis/bleeding) or severe azotemia Yes, Dialyzable toxin/drug poisoning (e.g. lithium, methanol, ethylene glycol, salicylate) Yes, Hemodynamically unstable (needs vasopressors/brain injury/raised ICP) Yes → Result: RRT initiation Emergent indication present（Determination: Emergent indication present: refractory hyperkalemia, severe acidosis (pH < 7.1), volume overload/pulmonary edema, uremia/severe azotemia, dialyzable poisoning → start renal replacement therapy, Modality choice: CRRT (continuous; preferred over intermittent hemodialysis when hemodynamically unstable/brain injury/raised ICP, reducing blood-pressure and ICP swings), Management direction: Start RRT promptly and correct triggers concurrently; hemodynamic instability favors CRRT, effluent dose 20–25 mL/kg/h; anticoagulation preferably regional citrate (if no contraindication)）