I am new to this site, but I've just read gazpot's post from 3 years ago describing a feeling of drowning. This put me in mind of my mother who experienced the same symptoms. We both thought it was her COPD, but it was so bad that I called a doctor out. She was admitted to hospital and it turned out that Mum hadn't been taking her water tablets, which she is prescribed for stage 3 chronic kidney failure. So the drowning sensation was due to fluid retention and nothing at all to do with her lungs. Also, certain mineral deficiencies can cause severe breathlessness, leading to heart attacks if left untreated. I know this as I had a heart attack through a magnesium deficiency, after weeks of severe breathlessness that I had put down to asthma.