Any condition that causes a decrease in respiratory rate predisposes to which acid-base disorder?

• A. Respiratory alkalosis
• B. Metabolic acidosis
• C. Respiratory acidosis
• D. Metabolic alkalosis

Answer: (C)

Lower ventilation means less carbon dioxide is expelled. CO2 combines with water to form carbonic acid, which dissociates into hydrogen ions and bicarbonate, raising hydrogen ion concentration and lowering pH. That shift is respiratory acidosis. The body attempts to compensate by the kidneys retaining more bicarbonate, but the primary effect of a slower respiratory rate is CO2 buildup leading to acidosis. The other patterns aren’t driven by hypoventilation: too little CO2 causes respiratory alkalosis (opposite problem), while metabolic disturbances alter pH through bicarbonate or non-CO2 acids rather than via changes in ventilation.