Sir,The patient described by Darwich and Allaf1 is unlikely to suffer from simple metabolic acidosis. It is more likely that their patient suffered from a mixed disorder, namely, metabolic acidosis and respiratory alkalosis. This is because, if we calculate the expected pCO₂ for the degree of hypobicarbonataemia in their patient according to the formula2:

pCO₂ = ((1.5)(HCO₃) +8) ± 2

the value we obtain (21.5±2) is significantly higher than the measured pCO₂ of 9.5. A superimposed respiratory alkalosis with metabolic acidosis would explain the low pCO₂ found in their patient.

It would be interesting to know whether an underlying septic process was present that was treated with empirical antibiotic therapy.