Ventilators are used to either ventilate patients who have breathing difficulties or a loss of lung function, or they are used as gas mixing devices to condition the air inhaled by a patient. They therefore have ventilator gas connections, valves, controls for the valves and pressurised gas connections, to create gas pressure to inject air into the ventilating tubes or patient's lungs.

 

In operation the pressurised gas connections are often connected to a compressed air system, where the compressed air in the device operates a pneumatic pump, which transports the ventilator gases. However, the ventilator gases can be injected under pressure through the actual ventilator gas connections, meaning that the pressure required for ventilation is provided by the ventilator gases themselves. Ventilators do exist which can be attached to a compressor, which creates the necessary ventilator gas pressure when in operation and injects this into the ventilator.

 

Conventional ventilators therefore consist of a housing unit, which contains the gas supply container, valves, controls and possibly batteries as emergency power supply for the electrical valve controls as well. The housing also contains the ventilator gas connections and connections for the ventilating tubes mentioned above. The connections are connected to the valves and the gas supply container via tubes inside the device. As these tubes take up a certain amount of constructional volume and adequate space must be available to fit these tubes, conventional ventilators must be of a certain size.