NBME 18 Answers ↦
could you clarify "later" timepoint, as I've seen several timepoints at which the mixed-disorder emerges from the initial resp' alkalosis
From UW question 1544: "Respiratory alkalosis occurs first as salicylates directly stimulate the medullary respiratory center, resulting in increased ventilation and loss of CO2 in expired air. Anion gap metabolic acidosis begins to develop about 12 hours later as high concentrations of salicylates increase lipolysis, uncouple oxidative phosphorylation, and inhibit the citric acid cycle. This results in the accumulation of organic acids in the blood (e.g. ketoacids, lactate, pyruvate) which bind bicarbonate, thereby increasing the calculated ion gap."