Hello and welcome to MedHelp's forums. Thank you for your question, we appreciate it. We are very sorry to hear about your friend. Has he had any recent procedures? This most commonly happens after that type of thing. Did your friend have COPD prior to this situation? Typically subcutaneous emphysema is self limiting, however, if severe, should likely be treated. I am not sure from what you write the extent of your friend's situation. Basically it means air is trapped in the skin. Again, this usually typically is self limiting and doesn't require treatment and happens after a procedure has been undergone by the patient. A collapsed lung can be serious and this I would hope was addressed. Can you give us an update on your friend?
Subcutaneous emphysema is usually visible and you can see a smooth bump on the skin.