A patient who was involved in a motor vehicle crash has had a tracheostomy placed to allow for continued mechanical ventilation. How should the nurse interpret the following arterial blood gas results: pH 7.48, PaO2 85 mm Hg. PaCO2 32 mm Hg, and HCO3 25 mEq/L?

Rationale: A. This occurs when there is hypoventilation, leading to elevated PaCO2 and decreased pH. In this case, the PaCO2 is low (32 mm Hg) and the pH is high (7.48), so this is not consistent with respiratory acidosis. B. The high pH (7.48) indicates alkalosis, and the low PaCO2 (32 mm Hg) shows that the alkalosis is caused by excessive exhalation of CO2, characteristic of respiratory alkalosis. The HCO3 is normal, indicating the kidneys have not yet compensated. C. Metabolic acidosis is characterized by a low pH and low HCO3. Here, the pH is elevated and HCO3 is normal, so this is not consistent with metabolic acidosis. D. Metabolic alkalosis would present with high pH and elevated HCO3, often due to vomiting or diuretic use. In this scenario, HCO3 is normal, indicating the alkalosis is not metabolic in origin.