Critical care/trauma Dr here.

I had one guy come in once with really bad facial trauma to the point where he had obstructed his nasal/oral passages and couldn't breathe. I had one quick attempt at intubation (passing a breathing tube into his lungs) but couldn't see anything when I opened his mouth but blood and swelling. So I went to cut his neck and pass the tube that way. Whilst I was doing that, his heart stopped from lack of oxygen. I got the tube into his neck and we started CPR and got him back.

As we were stabilising him, he starts coughing.

One big cough later and the tracheostomy tube I'd put in got dislodged. Unfortunately I wasn't able to reinsert it as there was now so much trauma to his neck I couldn't find the track, and he died.

With everything that was going on with him, I'd forgotten to give him muscle paralysis after the tube went in, which would have prevented him coughing. I've since been reassured by others that they don't always give muscle relaxant in this situation, but it still plays in my mind as a 'what if' scenario to this day