Patent ID: 7905231

Claim:
A breathing assistance apparatus capable of operating in alternating inhalation and expiratory phases, the apparatus comprising: a pressurized respiratory gas source, an inhalation duct to supply gas from the pressurized respiratory gas source to a patient, an expiratory duct for expiratory gas of the patient, an inhalation valve disposed on the inhalation duct, the inhalation valve comprising means to allow the gas from the gas source to pass to make possible proportional operation an expiratory valve on the expiratory gas duct to help establish a positive expiratory pressure, a pressure sensor and a flow rate sensor associated with the inhalation duct, and a comparator configured for transmitting an operating reference value of a gas related parameter to the pressurized respiratory gas source for the control of said gas source operation between or during the inhalation and expiratory phases, said computer having a first input for one or more reference values of the gas related parameter, and a second input being connected to a switch configured for real time selective connection of the comparator with the pressure sensor or the flow rate sensor, allowing real time transmission of a pressure signal or flow rate signal, the position of said switch determining a barometric or volumetric mode of the apparatus between or during the inhalation and expiratory phases, said switch being controlled by an automatic control unit, distinct from the comparator, said automatic control unit controlling the inhalation valve operation and receiving measurements from the pressure sensor and the flow rate sensor.