Hilda is a 74-year-old woman with a long history of severe COPD. She has smoked most of her life and has totaled around 80 pack years, but she stopped smoking 2 months ago. Her normal exercise tolerance is approximately 40 yards at a slow pace and less than one flight of stairs. She has been admitted to the hospital for acute infective exacerbations of COPD twice within the last 12 months. Although hypoxic during acute exacerbations, she has never been in acute respiratory failure, and she has not been hypoxic enough when reviewed in outpatient visits to fulfill the criteria for long-term oxygen therapy. She lives with her husband, and they are independent in their daily activities.

Vital Signs
T = 100.8⁰F; HR = 110; RR = 30

Blood Gases
pH 7.20
PaO₂ 48 mm Hg
PaCO₂ 56 mm Hg
Observation
Febrile. Prolonged expiration and pursed lip breathing. Using accessory muscles of respiration to breathe.

Which physiologic findings indicate Hilda may require some form of mechanical ventilation? (select all that apply)
A. pH 7.20
B. PaO₂ 48 mm Hg
C. PaCO₂ 56 mm Hg