A 75-year-old man with a long history of COPD is brought to the emergency department with shortness of breath

He has a persistent, productive cough with green purulent sputum, cyanosis of the lips and ex-tremities, and is uncooperative. His arterial blood gas values on 2 L/min by nasal cannula are: pH = 7.25; PaCO2 = 90 mm Hg; PaO2 = 38 mm Hg; SaO2 = 59%; HCO3? = 38 mEq/L. The most ap-propriate action at this time is which of the following?
a. IPPB
b. Mask CPAP
c. NIV via full face mask
d. Invasive mechanical ventilation

ANS: D
This patient meets the blood gas criteria for moderate to severe respiratory failure and therefore needs ventilatory support, as evidenced by the pH <7.35 and the PaCO2 >45 mm Hg; the PaO2/FIO2 is estimated at 38/0.28 = 136. This patient is at risk for failure of NIV because he is uncooperative (probably due to hypoxia) and has excessive secretions, as evidenced by his per-sistent productive cough.