In In the late 1800’s compressed or rarified air was proposed as a treatment for respiratory diseases by Dr. Waldenburg.  This apparatus is based on Dr. Waldenburg’s original device and is a modification of the Hutchinson spirometer.  From The Inhalation Treatment of the organs of respiration including Consumption.  By Arthur Hill Hassal, MD.  1885. In the text of the book Dr. Hassal indicates that this treatment has been found harmful to patients.