Timing of renal replacement therapy in acute kidney injury

Question

A 64-year-old man is in ICU on day 3 of septic shock from a perforated viscus. His vasopressor requirement is falling but he has developed KDIGO stage 3 acute kidney injury: creatinine has risen to 360 micromol per litre from a baseline of 80, and his urine output is 15 mL per hour. His potassium is 5.1 mmol per litre, pH 7.30, and he is 3 litres in positive balance. Outline the indications for renal replacement therapy in acute kidney injury and discuss the evidence on the optimal timing of its initiation.