When evaluating an ABG from a client with a subdural hematoma, the nurse notes the PaCO2 is 30 mm Hg. Which of the following responses best describes this result?: (A) Appropriate; lowering carbon dioxide (CO2) reduces intracranial pressure (ICP)., (B) Emergent; the client is poorly oxygenated., (C) Normal, (D) Significant; the client has alveolar hypoventilation.
Answer is A. A normal PaCO2 value is 35 to 45 mm Hg. CO2 has vasodilating properties; therefore, lowering PaCO2 through hyperventilation will lower ICP caused by dilated cerebral vessels.

Option B: Oxygenation is evaluated through PaO2 and oxygen saturation.
Option D: Alveolar hypoventilation would be reflected in an increased PaCO2.