Principles of Operation
Operative definition
The NEUMOVENT Graph Ventilator is a pressure or flow controller. The inspiration is
triggered by pressure, flow, time or manually. It is pressure, volume or flow limited and
pressure, volume, flow or time cycled.
Two proportional valves, one for air and another for oxygen regulate the flow of gas to the
patient. The valves work simultaneously during each respiratory phase mixing the gases to
get the set FIO
2
.
The microprocessor receives the airway pressure and the inspiratory flow signals, and it
controls the orders for the adjusted variables and the output signals. The airway pressure
sensor is connected at the beginning of the patient's circuit. This sensor also manages the
feedback signals that are used for pressure triggering, alarms levels, and to control the
pressure waves in the pressure controlled, pressure support and mandatory minute
ventilation modes. Two differential pressure transducers related with the internal and external
pneumotachographs obtain the information of the delivered and exhaled flow. The two output
pneumotachographs are screen type; the expiratory is of variable orifice. Also, the signals of
the first are used to control the flow waveform and the tidal volume regulated as reference.
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