Ventilatory muscle training apparatus

A ventilatory muscle training apparatus including a gas rebreathing system having a reservoir means and a mouthpiece connected to said reservoir means for use by an individual in conveying gas into and out of said reservoir means during inhalation and exhalation and a gas content control means for venting some exhaled gas from said rebreathing system to the ambient during the use of said rebreathing system and for supplying some makeup ambient air to said rebreathing system during inhalation so that the gas inhaled through said mouthpiece has a carbon dioxide content within the physiological limits of the individual using said system which approximate the patient's normal mixed expired carbon dioxide level in which the improvement comprises:

• said reservoir means being larger than the lung capacity of a user and being substantially incapable of providing any resistance to the exhalation of gas through said mouthpiece into said reservoir means,
• said gas content control means comprises an adjustable aperture means located within said system sufficiently adjacent to said mouthpiece so that some of the expired gas during exhalation is vented to the ambient and so that some ambient air is drawn into said system through said aperture means so as to be inhaled through the use of said mouthpiece along with gas from within said reservoir means, and
• gas flow measurement means for measuring gas flow through said mouthpiece during inhalation and exhalation, said gas flow measurement means including indicating means for indicating whether or not said apparatus is being utilized at a desired breathing level.