Method and apparatus for the intermittent delivery of oxygen therapy to a person

An apparatus for carrying by a person and supplying dosages of an oxygen-containing gas to the respiratory tract in synchronization with the inhalation phase of the respiratory cycle comprising:

• (a) a low voltage step control relay with an on-off reciprocating valve with a step-controlled latching solenoid, and a gas inlet port on a surface of the apparatus adapted for connection to a source of oxygen-containing gas having a gas proportion regulator;
• means for reciprocally moving said step control relay from a closed non-gas flow position to an open gas flow position responsive to an electrical signal from a microcontroller of sufficient length of time to open said step control relay, for maintaining said step control relay in an open gas flow position without drawing further electrical current, and for moving said step control relay from a gas flow open position to a closed non-gas flow position responsive to with a subsequent electrical signal from a microcontroller of sufficient length of time to close said step control relay;
• (b) a low voltage microbridge mass gas flow sensor constructed of dual sensing elements flanking a central heating element, and said gas flow sensor by means of unsupported thin film with low heat capacity, sensing gas flow, said gas flow sensor being connected to a gas outlet port on a surface of the apparatus and adapted to be connected to the respiratory tract of a person, said gas flow sensor sensing the commencement of inhalation, the duration of oxygen containing gas flow, and the termination of inhalation, during each inhalation phase of the respiratory cycle and transmitting corresponding commencement, duration and termination information to a microcontroller;
• (c) a programmed low voltage microcontroller for receiving a first electrical signal from the gas flow sensor upon detection by the gas flow sensor of the commencement of inhalation, and for transmitting said first electric signal to the step control relay of sufficient duration to cause the step control relay to move to said open gas flow position;
• and for receiving a second electrical signal from the gas flow sensor upon detection by the gas flow sensor of the termination of inhalation, and for transmitting said second electric signal to the step control relay of sufficient duration to cause the step control relay to move to said closed non-gas flow position;
• (d) a portable low voltage rechargeable lithium battery for supplying electrical power for operating the low voltage gas flow sensor, the low voltage step control relay, and the low voltage microcontroller;
• (e) a liquid crystal display panel on the surface of the apparatus connected to the microcontroller and the gas flow sensor for displaying programmed data from said microcontroller, and data received from said gas flow sensor;
• (f) a keyboard on the surface of the apparatus connected to said microcontroller for enabling manual commands to be conveyed to said microcontroller;
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• (g) a cannula or mask connected to said gas outlet port, gas pressure changes in said mask or cannula being sensed by said gas flow sensor, which responds to gas pressure changes indicative of the commencement or termination of inhalation, and transmits corresponding electrical signals to the microcontroller;
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• (h) said apparatus having a total mass capable of being carried by a single person.