A 73 year old male brought in as a priority 1 for respiratory distress. He has a 1 week history of shortness of breath and had a collapse today. The patient is on FiO2 0.7

ABG as below

pH 7.191                                Na 134 mmol/l

pCO2 85mmHg                      K 4.9 mmol/l

pO2 70mmHg                         Cl 90 mmol/l

HCO3 31 mmol/l                     Glu 9.6mmol/l

Lactate 2.2                              Cr 93umol/l

1. Describe and interpret the ABG
2. What is the A-a gradient and what are causes of a raised A-a gradient?