A-4
the microprocessor-controlled valve 10 creates the preset inspiratory flow and expiratory
valve 17 closes. The drive gas goes into the bellows 45 and depresses the bag inside the
bellows to move downward. This forces the gas inside the bag to go through the sodalime
canister 34 to enter the patient lung until the end of inspiration. During expiration, valve 10
closes and expiratory valve 17 opens. The patient expires freely. The exhaled gas, mixed
with the fresh gas, goes into the bag to lift up the bag inside the bellows. The drive gas
outside of the bag is scavenged to the AGSS until the end of expiration.
During the ventilation, the ventilator performs real-time monitoring of airway pressure (paw)
and tidal volume (TV). If the paw or TV is outside of the user-preset alarm limits, an
audible and visual alarm occurs. When paw is higher than the limit value, the ventilator
enters expiratory state automatically to avoid causing injury to the patient. In addition, the
ventilator has a built-in pressure safety valve 12 which opens when the inspiratory pressure
exceeds approximately 100 cmH
2
O (10 kPa) to avoid sustained airway pressure.
A.2 Electrical System Structure
A.2.1 Electrical Block Diagram
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