Method and apparatus for providing and controlling oxygen supply

A method of controlling a flow of supplemental oxygen from an oxygen supply to a user through a delivery apparatus in an open-loop breathing system, the delivery apparatus including a valve moveable between a first position permitting oxygen to flow from said supply to said user and a second position for preventing oxygen to flow from said supply to said user, comprising the steps of:

• receiving a goal blood-oxygen saturation level of a user;
• determining an actual blood-oxygen saturation level of a user;
• determining a breath rate of said user;
• sensing periods of inhalation by said user;
• determining a length of time said valve should be moved to said first position in order to deliver a desired quantity of oxygen, said determining step comprising determining a first maximum time if said actual level has not reached said goal level or said actual level is below a minimum level, determining a second minimum time if said actual level is above said goal level, and determining a variable time if said actual level has at least once reached said goal level but said actual level is between said minimum level and said goal level, said step of determining a variable time including determining a breath rate of said user from said sensed periods of inhalation by said user, determining a delivery volume comprising a desired quantity of oxygen divided by said breath rate, and determining said variable time by dividing said delivery volume by a flow rate of supplemental oxygen available;
• detecting the initiation of inhalation by said user;
• and
• moving said valve from said second position to said first position for said determined length of time;
• and
• returning said valve to said first position.