83 years old woman with history of COPD and still smokes. Presented with SOB and drowsiness.

Her Arterial blood gas on room air showed the following

Ph = 7.31
PO2 = 31 mmHg
PCO2 = 76 mmHg
HCO3 = 34 mmol/L

Na = 135 mmol/L
K = 4.0 mmol/L
Cl = 95 mmol/L
Glucose = 11.2 mmol/L
Lactate = 2.4 mmol/L
Cr = 163 nmol/L
Hb = 178 g/l

Questions:

1. Interpret these results
2. What is the significance of A-a gradient ?
3. What management strategies you will consider in this case ?