This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Failure, Subject name: Medicine
On an ABG, pH of 7.2, pO2 of 46, pCO2 of 80 are indicative of: 
Select and explain. 
A. Acute exacerbation of COPD, B. Adult respiratory distress syndrome, C. Interstitial pneumonitis, D. Acute asthma
A: Acute exacerbation of COPD
Answer: A: Acute exacerbation of COPD 
Explanation: ABG shows severe hypoxia with hypercarbia with acidosis suggestive of type 2 respiratory failure. ARDS and acute asthma both have Type 1 Respiratory Failure and are ruled out. So we have to select between options A and C. Interstitial Pneumonitis on routine presentation will not have such low oxygen values but an acute exacerbation of chronic bronchitis will definitely present with low oxygen values.