ABG

pH

7.45

PaCO₂

20 mmHg

HCO₃

14 mmol/L

Na

140

Cl

100

Lactate

4 mmol/L

Interpretation

• • Near-normal pH but very abnormal CO₂ and HCO₃ → mixed
• • Low CO₂ alone would suggest primary respiratory alkalosis
• • AG = 140 − (100 + 14) = 26 → coexistent HAGMA
• • Classic salicylate pattern: respiratory alkalosis + HAGMA

Next steps

• • Salicylate level, paracetamol level, glucose
• • Activated charcoal if ≤1 h post-ingestion
• • Urinary alkalinisation (NaHCO₃ infusion) target urine pH 7.5–8.5
• • Haemodialysis if level >700 mg/L, renal failure, severe acidosis, pulmonary oedema, neurological signs