This old technique has faded away in time, since we have respirators and other machines. *In case the health system collapses and you cannot go to the hospital*, keep this technique in mind. Don’t wait until the last minute.
If you feel any difficulty in breathing or a lot of mucus, inhale and exhale slowly in this position, for 15 to 20 minutes, 3 times a day or as long as you need.
Don’t do it on a full stomach, and always away from meals. In a nursing home in Vietnam (1976) this technique was applied during the influenza epidemic. No elderly person died, compared to other nursing homes where many died. Source: more