(A) In compensated respiratory acidosis, the pH level is normal, the PCO2level is elevated, and the HCO3level is elevated. The client’s primary alteration is an inability to remove CO2from the lungs, so over time, the kidneys increase reabsorption of HCO3to buffer the CO2. (B) Normal ranges for arterial blood gases for adults and children are as follows: pH 7.35–7.45, PO280–100 mm Hg, PCO235–45 mm Hg, HCO321–28 mEq/L. (C) In uncompensated metabolic acidosis the pH level is decreased, the PCO2level is normal, and the HCO3level is decreased. The client’s primary alteration is an inability to remove excess acid via the kidneys. The lungs are unable to clear the increased acid. (D) In uncompensated respiratory acidosis, the pH level is decreased, the PCO2level is increased, and the HCO3level is normal. In a person with long-standing COPD, the HCO3level will rise gradually over time to compensate for the gradually increasing PCO2, and the person’s pH level will be normal. When a person with COPD becomes acutely ill, the kidneys do not have time to increase the reabsorption of HCO3, so the person’s pH level will reflect acidosis even though the HCO3is elevated.