I've looked into this myself and find it interesting. I think it may be related to dyspnea in general or air hunger all of which are different terms for a similar thing. I think it does accurately describe what many are experiencing. The mental reassurance that I'm not in danger plus the breathing exercises, and a good diet and controlled exercise have helped me greatly over the years. I can tell you're very invested in finding correlations and information on a variety of causes and possibilities. It's certainly a journey of looking at various things, implementing some strategies, and tweaking along the way. Have you developed any strategies or solutions that have helped you along?

look up sighing dyspnea and psuedo dyspnea, or anxiety. im trying to help call me biased whatever, i understand some of you have real comditions but some dont and its false and your lives are there for the living if you treat this sensation as unimportant. good luck guys