A 61-year-old female was admitted last night with shortness of breath. She currently is alert and oriented but very anxious

Her latest arterial blood gas values, on a nasal cannula at 3 L/min, show: pH = 7.39; PaCO2 = 41 mm Hg; PaO2 = 40 mm Hg; SaO2 = 74%; HCO3? = 24 mEq/L. Breath sounds are decreased throughout with fine late crackles on inspiration. The current chest X-ray shows an enlarged heart with bilateral vascular congestion. The most appropriate therapy for this patient is _________.
a. NIPPV
b. mask CPAP
c. invasive ventilation
d. nonrebreather mask

ANS: B
The arterial blood gas values for this patient show refractory hypoxemia, as evidenced by the PaO2 of 40 mm Hg while receiving supplemental oxygen. The breath sounds indicate pulmonary edema. This finding is supported by the chest X-ray, which shows bilateral vascular congestion and an enlarged heart. These findings are consistent with acute cardiogenic pulmonary edema. The most appropriate therapy is mask CPAP.