Yoga Techniques to clean the body
They are called sapta-kriya, "the seven practical acts", or sapta-karma, "the seven actions," and are part of these initial exercises all bodily purifications, real cleaning that depart from the body, designed to remove the contaminated material body, to remove bodies and organs all impurities accumulated.
Many of these practices, I find, personally, especially exaggerated because according to some Yoga teachers should be performed continuously: the gesture of the shell (see link below) for example, practice is extremely healthy bowel with exceptional benefits, if done once a year or at most to the change of season if the intestine is really compromise, leads instead to destroy the intestinal bacterial flora if it is run frequently (eg once a month).
So also is made for the cleaning of the stomach with the gauze, and for the cleaning of the nose with the cannula, because both can cause irritations.
The vomiting is caused, in my opinion excessive and may over time become harmful, then inducing a revolt of the stomach too easily at the slightest discomfort: you can also get to induce vomiting, spitting the toothpaste to brush your teeth.
Having said that following the techniques used with caution, always under the supervision of a trained yogi and only if you have recently carried out a medical examination to determine your state of health: remember never to exceed, for the law of health is in 'balance.