A ventilator system for providing respiratory support in cases of acute respiratory failure or severe trauma is described. The ventilator system comprises a ventilator and a tubing system. The system is characterized in that the ventilator comprises a continuous bleed valve configured to be open to air flow from the blower at all times when the blower is operating during both inspiration and expiration; thereby providing a minimal amount of pressure within a patient's lungs at the end of each exhalation positive end expiratory pressure (PEEP). In an embodiment of the invention the system comprises a manifold block configured to hold the main operating elements of ventilator.

The invention relates to a fluid delivery device (2, 2) for delivering a fluid into a human or animal body. The fluid delivery device (2, 2) comprises a fluid chamber (4, 4) for receiving a fluid, an oscillator (6, 6) for imparting oscillations to at least a portion of the fluid and a control for controlling the oscillator (6, 6). The oscillator (6, 6) comprises a vibrator (8, 8) and a resonator (10, 10). The resonator (10, 10) has a main body (12, 12), defining an interior volume (14, 14), and a neck (16, 16). The neck (16, 16) is connected to the main body (12, 12) and in fluid communication with the interior volume (14, 14). The vibrator (8, 8) is configured to impart vibrations to the resonator (10, 10). The control is configured to control operation of the vibrator (8, 8) so as to impart vibrations to the resonator (10, 10) at a resonance frequency of the resonator (10, 10) or at a frequency which is within 20% of a resonance frequency of the resonator (10, 10). The invention further relates to a method of operating the fluid delivery device (2, 2).

An oxygen concentrator includes one or more adsorbent sieve beds operable to remove nitrogen from air to produce concentrated oxygen gas at respective outlets thereof, a product tank fluidly coupled to the respective outlets of the sieve bed(s), a compressor operable to pressurize ambient air, one or more sieve bed flow paths from the compressor to respective inlets of the sieve bed(s), a bypass flow path from the compressor to the product tank that bypasses the sieve bed(s), and a valve unit operable to selectively allow flow of pressurized ambient air from the compressor along the one or more sieve bed flow paths and along the bypass flow path in response to a control signal. The valve unit may be controlled in response to a command issued by a ventilator based on a calculated or estimated total flow of gas and entrained air or % FiO.sub.2 of a patient.

A breathing assistance apparatus includes an inner volumetric member pressurizable from a first pressure to a second pressure and an outer volumetric member surrounding at least a portion of the inner expandable volumetric member. The inner volumetric member pressurizes the outer volumetric member as the inner volumetric member is pressurized from the first pressure to the second pressure. In another embodiment, a breathing assistance apparatus includes exhalation and inhalation chambers with respective biasing members providing for the exhalation chamber to apply a pressure to the inhalation chamber and thereby provide assisted inhalation. Methods for assisting breathing are also provided.

An oxygen concentrator includes one or more adsorbent sieve beds operable to remove nitrogen from air to produce concentrated oxygen gas at respective outlets thereof, a product tank fluidly coupled to the respective outlets of the sieve bed(s), a compressor operable to pressurize ambient air, one or more sieve bed flow paths from the compressor to respective inlets of the sieve bed(s), a bypass flow path from the compressor to the product tank that bypasses the sieve bed(s), and a valve unit operable to selectively allow flow of pressurized ambient air from the compressor along the one or more sieve bed flow paths and along the bypass flow path in response to a control signal. The valve unit may be controlled in response to a command issued by a ventilator based on a calculated or estimated total flow of gas and entrained air or % FiO.sub.2 of a patient.

There is described herein a system for determining the interaction between a test atmosphere and a simulated respiratory tract, said system comprising: (a) a first pump comprising: (i) a chamber configured for containing a first volume of gas comprising a test atmosphere; (ii) a first port adapted for receiving and outputting gas and comprising a valve for regulating the flow of gas through the first port, said valve being moveable between open and closed positions, wherein in the open position said valve is openable towards a test atmosphere or surrounding air; (iii) a second port adapted for outputting and receiving gas and comprising a valve for regulating the flow of gas through the second port, said valve being moveable between open and closed positions; (iv) a piston plate in the chamber, said piston plate comprising one or more apertures for the uptake or inflow of gas into the chamber wherein one or more, or each, of the apertures include a valve that is movable between open and closed positions and is capable of regulating the uptake or inflow of gas; (b) a second pump comprising: (i) a chamber configured for containing a second volume of gas, wherein the first and second volumes of gas are different; (ii) a port adapted for receiving and outputting gas; and (iii) a motor for controlling the operation of the second pump; (c) a connecting structure operable to transmit the gas from the first pump into the second pump; and (d) one or more openings in the first pump or the second pump or the walls of the connecting structure or a combination of two or more thereof, said openings being capable of receiving a module for containing a cell culture medium or for monitoring conditions in the chamber or for gas sampling or for gas characterisation.