In respiratory acidosis, a compensatory mechanism is the increase in which parameter?

• A. Increased Respiratory Rate
• B. Ammonia Formation
• C. Increased Blood PCO2
• D. Increased Plasma Bicarbonate Concentration

Answer: (D)

When carbon dioxide accumulates in the blood, lowering the pH (respiratory acidosis), the body’s main compensatory response is to boost bicarbonate levels. The kidneys do this by reabsorbing more bicarbonate and producing new bicarbonate, so the plasma HCO3− concentration rises. This buffering helps neutralize the excess hydrogen ions from the retained CO2 and brings the pH back toward normal, especially in chronic cases where renal compensation has had time to fully develop.

In the long run, this renal adjustment is the key compensatory mechanism. Increased respiratory rate would not serve as a true compensatory mechanism for respiratory acidosis because the problem is CO2 retention from ventilation; simply breathing faster does not correct the underlying cycle and can even worsen CO2 retention if ventilation is ineffective. Increased blood PCO2 is the cause of the acidosis, not a compensatory change. Ammonia formation is unrelated to this acid-base compensation.