Respiration apparatus

Claim 1

RESPIRATION APPARATUS, COMPRISING: A REGULATED SOURCE OF PRESSURIZED GAS, THE PRESSURE OF SAID GAS BEING ADAPTED TO BE PRESET; A MASK ADAPTED TO BE CONNECTED TO A PATIENT''S RESPIRATORY SYSTEM; DELIVERY CONDUIT MEANS COUPLED AT ONE END TO SAID SOURCE AND AT THE OTHER END TO SAID MASK; VALVE MEANS IN SAID CONDUIT MEANS ADAPTED TO BE CYCLED BETWEEN AN INSPIRATION POSITION, WHEREIN FLOW OF GAS TAKES PLACE THROUGH SAID CONDUIT MEANS FROM SAID SOURCE TO SAID MASK, AND AN EXPIRATION POSITION WHEREIN SUCH FLOW IS BLOCKED; A VARIABLE FLOW RESTRICTOR IN SAID DELIVERY CONDUIT MEANS INCLUDING ORIFICE MEANS IN SAID DELIVERY CONDUIT MEANS AND CLOSURE MEANS COOPERABLE WITH SAID ORIFICE MEANS AND MOVABLE RELATIVE THERETO TO VARY THE SIZE THEREOF, SAID CLOSURE MEANS BEING BIASED TOWARD A POSITION WHEREIN SAID ORIFICE IS OF A MINIMUM SIZE; DIAPHRAGM TYPE SENSING MEANS OPERATIVELY CONNECTED TO SAID VALVE MEANS AND TO SAID CONDUIT MEANS, SAID SENSING MEANS BEING RESPONSIVE TO A PREDETERMINED NEGATIVE PRESSURE AT SAID MASK FOR CYCLING SAID VALVE MEANS TO ITS INSPIRATION POSITION AND TO A PREDETERMINED MINIMUM FLOW INDEPENDENT OF ABSOLUTE PRESSURES IN SAID CONDUIT MEANS FOR CYCLING SAID VALVE MEANS TO ITS EXPIRATION POSITION; FIRST ADJUSTMENT MEANS FOR ADJUSTABLY ESTABLISHING THE PREDETERMINED NEGATIVE PRESSURE AT WHICH SAID SENSING MEANS CYCLES SAID VALVE MEANS TO ITS INSPIRATION POSITION; AND SECOND ADJUSTMENT MEANS SUBSTANTIALLY INDEPENDENT OF SAID FIRST ADJUSTMENT MEANS FOR ADJUSTABLY ESTABLISHING THE PREDETERMINED MINIMUM FLOW AT WHICH SENSING MEANS CYCLES SAID VALVE MEANS TO ITS EXPIRATION POSITION.