Case 1 · Acid–base
DI-01A 58-year-old woman is being resuscitated for postoperative intra-abdominal sepsis. She is tachypnoeic and has marked hypoalbuminaemia. Arterial gas and venous chemistry samples are obtained at the same time, before further fluid treatment. The laboratory calculates its anion gap without potassium. Which interpretation best integrates all the results?
| Investigation | Result | Reference / context |
|---|---|---|
| Arterial pH | 7.31 | 7.35–7.45 |
| PaCO₂ | 3.9 kPa | 4.7–6.0 |
| Bicarbonate | 14 mmol/L | 22–26 |
| Sodium / chloride | 138 / 108 mmol/L | 135–145 / 95–108 |
| Albumin | 16 g/L | 35–50 |
| Lactate | 5.7 mmol/L | 0.5–2.0 |
| Anion-gap reference | 8–16 mmol/L | Without potassium |