A patient with an opiate drug overdose is unconscious and has the following ABG results on room air: pH 7.20; PaCO2 88 mm Hg; PaO2 42 mm Hg; HCO3? 25 mEq/L. Which of the following best describes this patient's condition?

a. Chronic hypoxemic respiratory failure
b. Chronic hypercapnic respiratory failure
c. Acute hypoxemic respiratory failure
d. Acute hypercapnic respiratory failure

ANS: D
A drug overdose will affect the patient's central nervous system, knocking out the patient's res-piratory center. This will cause an increase in the partial pressure of carbon dioxide in the arteries (PaCO2). The alveolar hypoventilation is causing the low partial pressure of oxygen (PaO2). If this was a chronic hypercapnic respiratory failure the patient's bicarbonate level would be elevated above the normal level.