[The breathing casette; a useful aide in hyperventilation].

The breathing cassette (Hyperfree) was tested on 10 persons suffering from hyperventilation syndrome. Each subject performed a hyperventilation provocation of two minutes on three separate occasions. Immediately after the hyperventilation provocation the subject was asked to terminate the hyperventilation, firstly with no aid at all, later using a plastic bag or the breathing cassette. The %vol. CO2 in the exhaled air was recorded with a capnograph. The use of the plastic bag and the breathing cassette resulted in an equal restoration of the %vol. CO2. After using the cassette for six weeks the patients completed a questionnaire. All patients stated that they intended to continue using the breathing cassette, and that it was easy and handy to use. Most patients carried the cassette always with them, since it made them feel comfortable.