Acute salicylate overdose — acid-base, bicarb, dialysis

(i) Acid-base diagnosis. A raised pH with a low PaCO2 is a respiratory alkalosis, and the raised anion gap with a low bicarbonate shows a coexisting anion gap metabolic acidosis — the pattern salicylates produce through respiratory centre stimulation and uncoupling of oxidative phosphorylation.^[1]

(ii) Immediate management. Consult a medical toxicologist or poison centre.^[1] Resuscitate with intravenous fluid; an initial deficit of up to 4–6 L has been reported.^[1] Activated charcoal is appropriate after salicylate ingestion, with an additional dose to complete decontamination.^[5] Start sodium bicarbonate: the review describes a 1–2 mEq/kg bolus then an infusion of 150 mEq in 1 L of 5% dextrose at 2–3 mL/kg/hour (no study supports specific dosing), targeting a serum pH of 7.50–7.55 and a urine pH above 7.5.^[1] Her potassium of 3.1 must be corrected, because urinary alkalinisation cannot be achieved while hypokalaemia persists.^[1] Urine alkalinisation is first-line for moderately severe poisoning that does not meet haemodialysis criteria.^[3]

(iii) Haemodialysis. Her concentration of 750 mg/L (75 mg/dL) is below the EXTRIP concentration thresholds of 100 mg/dL, or 90 mg/dL with impaired kidney function, and she has no altered mental status, no ARDS and a pH above 7.20; she does not currently meet criteria, but EXTRIP also recommends extracorporeal treatment if standard therapy is failing (and suggests it from 90 mg/dL, or 80 mg/dL with impaired kidney function). Acute ingestions need serial concentrations, so repeat the level and reassess.^[2][1]