Case: 

A 73-year-old man presents to the hospital with altered mental status. He is well-known to the pulmonary clinic, who has cared for him the last 10 years. He has very severe COPD, with his last FEV₁ measured at 18% predicted earlier this year. He uses 3 liters of supplemental oxygen at rest and with exertion. Other comorbidities include coronary artery disease, peripheral vascular disease, and type 2 DM. His medications include insulin, a beta-blocker, aspirin, and an ACE inhibitor. COPD medications include a long-acting beta-agonist/inhaled corticosteroid combination inhaler twice a day, tiotropium daily, and albuterol as needed. His family reports he became confused earlier this morning. He has had a runny nose and sore throat the past 2 days, similar to an illness his grandson had last week. His vital signs are notable for tachypnea with a respiratory rate of 42 breaths per minute and tachycardia with a heart rate of 122 bpm. His exam is notable for him being a very thin, elderly man in obvious distress, arousable only to sternal rub. He has diminished air movement in all lung fields. Laboratory values are drawn before interventions are started. Laboratory results are as follows:

Question 1 of 3

What is/are the primary acid-base disturbance occurring in this case?

A: Metabolic acidosis only

B: Respiratory acidosis only

C: Metabolic acidosis and a respiratory acidosis

D: Metabolic alkalosis and a respiratory alkalosis

E: Metabolic alkalosis

F: Respiratory alkalosis

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