What the hell is going on here? Still no answer that makes sense. We have:

• "Poor air movement, especially on the LEFT"
• What looks like a RIGHT tension pneumothorax on CXR
• Shock and stupor ensue...
• Oh, and also hypovolemic shock and maybe a weirdly shifted PMI

Put it all together: RIGHT tension pneumothorax

But why the hell are breath sounds decreased on the LEFT? That alone made me switch to some crazy heart crushing atelectasis answer. I honestly thing the R/L mixup may be a typo because without that the question is simple.

The radiograph is showing complete collapse of the left lung (2/2 mucous plugging) with resultant severe ipsilateral mediastinal shift. An acute shift can have the same effect as any other “tension”-type process, causing impaired venous return to the heart and decreased cardiac output via the Starling mechanism.