In acid-base disorders, which indicator suggests a metabolic process?

The correct choice indicates a situation where both pCO2 and pH change in the same direction, which suggests a metabolic process affecting the acid-base balance. In metabolic acidosis or alkalosis, the primary disturbance is metabolic, leading to compensatory changes in pCO2.

When the body undergoes metabolic acidosis (characterized by a decrease in pH), the respiratory system responds by increasing the rate and depth of breathing to expel more carbon dioxide (CO2), which helps to raise the pH back toward normal. Conversely, in metabolic alkalosis (characterized by an increase in pH), the respiratory system may decrease ventilation to retain CO2, which contributes to lowering the pH back toward normal.

This coordinated change, where both pH and pCO2 move in the same direction, highlights that a metabolic process is at play, as the body is making adjustments in response to a metabolic disturbance. Therefore, the observation of pCO2 and pH moving together is indicative of a primary metabolic change rather than a respiratory one.