Step 1: Look at the patient. The clinical history can provide clues and help with the interpretation of the results.
Step 2: Look at PaO2 to determine if it is normal or there is hypoxaemia. If hypoxic check which type of respiratory failure it is and if the patient is on oxygen.
Step 3: Look at the pH level and determine if it is normal, acidic or alkalotic. If normal, determine which side is it closer to as there may be compensation.
Step 4: Look at the PaCO2 level and determine if it is normal, increased or decreased.
Step 5: Look at the HCO3 level and determine if it is normal, increased or decreased.