Abstract: A resuscitation/ventilation apparatus incorporates an entrainment mixer with a nozzle, discharging entraining gas into an entrainment chamber, the nozzle being connected with a high pressure source of the entraining gas. One entrainment port to the entrainment chamber is connected to atmosphere and another entrainment port is connected to an oxygen source. A continuously variable restriction is disposed in the oxygen supply conduit upstream of the other entrainment port and is variable independently of any control of the entraining gas supply, to enable delivery of a gas mixture of steplessly variable oxygen concentration.

Abstract: A ventilator for inducing or assisting lung function in humans is characterized by a control system that provides for semi-automatic operation in which a single complete ventilation cycle in accordance with predetermined ventilation parameters (tidal volume, durations of inhalation and exhalation phases) is initiated by operation of a trigger. The ventilator is particularly useful in one-man resuscitation by CPR. The control system may require a discrete trigger operation to initiate each successive ventilation cycle or it may provide for continuous operation with timed successive cycles, in the manner of an automatic ventilator, by holding or latching the trigger. Various embodiments based on gas-powered ventilators are disclosed but the invention is also applicable to electrically operated or controlled ventilators. In a typical embodiment (FIG.

Abstract: A lung ventilator system has a demand valve to provide for spontaneous breathing with modification of the ventilator action to complement the spontaneous breathing and to synchronize restored forced ventilation with a last spontaneous breath. The system includes means to detect gas flow in the supply to the demand valve and to output a signal to the oscillator to modify or inhibit its operation in relation to the volume of gas drawn from the demand valve to vary the duration of the exhalation phase of the ventilation cycle. The system preferably uses a pneumatic oscillator with a feedback circuit connected to be influenced by the pressure drop across a restriction in the supply to the demand valve, signalled by the operation of selected ones of a plurality of inhibitor valves responding to different pressure drop levels.

Abstract: A pneumatic oscillator especially useful for generating breathable gas pulses in a resuscitator and/or lung ventilator device has a reciprocable piston or equivalent controlling a poppet valve arrangement that includes a sealing lip coacting with a resilient facing. The sealing lip provides for sharp definition of a line of contact on the resilient facing and penetration of the latter by the lip is limited by stop means, preferably abutment(s) coacting with the facing adjacent to the line of contact with the sealing lip. This prevents wear and/or excessive indentation of the facing with consequent shift of the contact line and alteration of the oscillator characteristic with time.

Abstract: An enhanced system for cleaning a component, such as a blanket, of a printing press in one embodiment provides circulation of wash mixture around a path in such a way that pressure of fluid in the supply line can never exceed ambient pressure. This may be achieved, for example, by utilizing a pump disposed in the return line (rather than in the supply line). Another embodiment provides a spray arrangement for spraying wash mixture onto the component to be cleaned. The spray arrangement has nozzles that are in communication with a feed region (such as the interior of a spray bar) and an isolation valve arrangement for in an open state permitting and in a closed state preventing fluid pressure transmission from the rest of the system to the feed region. A pressure arrangement modifies fluid pressure in the feed region when the isolation valve arrangement is in a closed state.

Abstract: A pneumatic oscillator of the type having an operating piston reciprocable in a cylinder to control a poppet valve arrangement so as to control a gas flow path, and biassed to the flow path-closing condition with feedback of output supplementary to the bias in opposition to source pressure, is characterized by a piston seal comprising an O-ring having both radial and axial clearance in a retaining groove in the piston to provide low friction, and by a resilient buffer to arrest the piston at its stroke-end in the flow path-opening position and to cause piston rebound to an extent to position the O-ring against the lateral groove wall that is downstream to the prevailing pressure differential, thereby to ensure effective sealing at the switching point. The buffer also suppresses noise of operation of the oscillator. The oscillator is particularly useful for generating breathable gas pulses for resuscitation and/or lung ventilation purposes.

Abstract: A portable resuscitator/ventilator device especially intended for emergency use and powered by pressurized primary breathable gas such as oxygen or compressed air from a bottle comprises a control unit that outputs primary gas pulses to a patient valve that includes an entrainment mixer for diluting the primary gas with air. The entrainment mixer is selectively operable to that the patient valve delivers primary gas or air-diluted primary gas as required. The control unit includes a fixed value flow-control restrictor that passes a required tidal volume of primary gas for undiluted delivery to the patient and the impedance of the patient valve is arranged to increase when the entrainment mixer is operational so that flow of the primary gas is automatically reduced to provide the required tidal volume of air-diluted primary gas without wastage of primary gas or any adjustment of the control unit.