In metabolic acidosis what happens to PCO2 -

The fall in blood pH is accompanied by a characteristic increase in ventilation, especially the tidal volume (Kussmaul respiration). Metabolic acidosis due to an increase in endogenous acids (e.g., ketoacidosis) lowers extracellular fluid and decreases extracellular pH. This stimulates the medullary chemoreceptors to increase ventilation and to return the ratio of to Paco2, and thus pH, toward, but not to, normal.Compensatory responses for primary metabolic disorders move the Paco2 in the same direction as the change in , whereas, conversely, compensation for primary respiratory disorders moves the in the same direction as the primary change in Paco2 .Therefore, changes in Paco2 and in opposite directions indicate a mixed disturbance. ( ref: harrisons, 19E, 316)