Respiratory therapy apparatus
A respiratory therapy apparatus includes a rocker mechanism ( 101, 110, 111, 112 ) that provides an oscillating resistance to expiration. The apparatus also includes an air entrainment arrangement ( 200 ) at its air inlet ( 3 ) having a ring orifice ( 214 ) connected via a gas inlet ( 4 ) to a source ( 119 ) of oxygen at elevated pressure. The oxygen emerging around the ring orifice ( 214 ) entrains ambient air and supplies this as a continuous flow of respiratory gas to the patient interface ( 2 ) to provide a positive airway pressure.
1. Respiratory therapy apparatus including a respiratory therapy device having a patient interface and a valve arranged to produce an oscillating resistance to expiratory flow through the device, characterised in that the therapy apparatus additionally includes an arrangement for generating a continuous flow of inspiratory respiratory gas to the patient interface, that the arrangement includes a gas inlet arranged to receive a supply of respiratory gas at elevated pressure and an air entrainment device arranged to receive the gas from the inlet to entrain air drawn into the arrangement so as to amplify the flow of air at a positive airway pressure to the patient interface, the apparatus further including a second valve positioned between the respiratory therapy device and the arrangement such that the second valve closes to isolate the air entrainment device during expiratory flow.
2. Apparatus according to claim 1 , characterised in that the valve includes a valve element on a rocker arm that opens and closes an opening during exhalation through the apparatus.
3. Apparatus according to claim 1 , characterised in that the air entrainment device includes a ring orifice arranged to receive the gas at elevated pressure and to amplify inspiratory gas flow to the patient interface by entraining air through the orifice.
4. Apparatus according to claim 3 , characterised in that the ring orifice lies close to a free end of a conduit shaped with a Coanda profile such that a Coanda effect is provided with the gas received at a preferred flow rate to entrain the air drawn into the entrainment device towards the patient interface.
5. Apparatus according to claim 1 , characterised in that the respiratory gas at elevated pressure has an oxygen concentration at higher than atmospheric concentrations.
6. Apparatus according to claim 1 , characterised in that the apparatus includes an air flow tube opening at one end into the patient interface and opening at its opposite end into the entrainm ent device, and that the air flow tube opens into the valve arranged to produce an oscillating resistance to expiratory flow through the device at a location between the patient interface and the arrangement for generating a continuous flow of inspiratory respiratory gas.