Which ABG pattern is associated with acute salicylate overdose?

Which ABG pattern is associated with acute salicylate overdose?

• A. Anion gap metabolic acidosis with respiratory acidosis
• B. Nonanion gap metabolic acidosis with respiratory alkalosis
• C. Anion gap metabolic acidosis with respiratory alkalosis
• D. Nonanion gap metabolic acidosis with respiratory acidosis

Answer: (C)

The main concept is that acute salicylate overdose produces a mixed acid-base disturbance: anion gap metabolic acidosis together with a respiratory alkalosis. Salicylates increase organic acids in the body, causing a high anion gap metabolic acidosis, while they also stimulate the respiratory center, leading to tachypnea and CO2 blow-off, which causes respiratory alkalosis. Because both processes occur, the arterial blood gas shows features of metabolic acidosis with an elevated anion gap alongside a concurrent respiratory alkalosis (low PaCO2). Early in poisoning, the respiratory alkalosis may be prominent, and as the acidosis worsens, the two abnormalities coexist. Other patterns, like nonanion gap acidosis or respiratory acidosis alone, don’t fit the typical mechanism of salicylate toxicity.

The main concept is that acute salicylate overdose produces a mixed acid-base disturbance: anion gap metabolic acidosis together with a respiratory alkalosis. Salicylates increase organic acids in the body, causing a high anion gap metabolic acidosis, while they also stimulate the respiratory center, leading to tachypnea and CO2 blow-off, which causes respiratory alkalosis. Because both processes occur, the arterial blood gas shows features of metabolic acidosis with an elevated anion gap alongside a concurrent respiratory alkalosis (low PaCO2). Early in poisoning, the respiratory alkalosis may be prominent, and as the acidosis worsens, the two abnormalities coexist. Other patterns, like nonanion gap acidosis or respiratory acidosis alone, don’t fit the typical mechanism of salicylate toxicity.