The Correct answer is:

The air bubbles has room air gases. The room air PO2 is 150mm Hg and there is no CO2. 

The change secondary to the presence of the large air bubble will depend upon the value of the patient's arterial PO2. If it is low, the air bubble will make it high; and vice versa. 

The CO2 will always be lowered.

Hence, it is always a good idea to avoid air bubbles and express them immediately if any. If it was unavoidable, its presence should be mentioned for proper interpretation. 

REF: Heart and Lung 1983; 12:395-427