Anaesthesia

Which of the following is true to the immediate postoperative period in a young patient with previously normal lungs having upper abdominal surgery ?

Arterial oxygen tension will typically be reduced by an average of 10 mm Hg when breathing room air

Arterial oxygen tension will normalize after 15 minutes

Diffusion hypoxia is the major determinant of arterial hypoxaemia

The CXR will typically reveal no abnormalities