What combination of acid-base imbalances is typically seen in adults with aspirin overdose?

In adults who experience an aspirin overdose, the combination of metabolic acidosis and respiratory alkalosis is typically observed. This condition arises due to the physiological effects of salicylates on the body.

Aspirin (acetylsalicylic acid) metabolism can lead to increased production of organic acids, resulting in metabolic acidosis. As the acid load increases, the body attempts to compensate for the drop in pH by increasing respiratory rate to blow off carbon dioxide (CO2), which in turn leads to a decrease in the partial pressure of CO2 in the blood. This compensatory mechanism results in respiratory alkalosis.

The key factor in this scenario is the simultaneous occurrence of metabolic acidosis due to the accumulation of lactic acid and other acids from aspirin metabolism and the respiratory alkalosis caused by hyperventilation as a compensatory response to lower the acid load in the system. Understanding how these compensatory mechanisms work in response to the disturbance caused by the overdose is crucial in recognizing the acid-base imbalance that occurs in these patients.