A 28-year-old woman is brought to the emergency department 4 hours after intentional ingestion of aspirin. She is tachypneic (RR 32/min), with altered mental status and a blood pH of 7.08 with anion-gap metabolic acidosis. Serum salicylate level is 118 mg/dL. The AEIOU mnemonic for dialysis indications is displayed. The structure marked **C** in the diagram represents a category of poisonings amenable to hemodialysis. Which of the following is the MOST appropriate indication for initiating hemodialysis in this patient?