B- Assist Control Mode - BIO-MED DEVICES CROSSVENT-3+ Operation & Service Manual

VIII THEORY OF OPERATION- cont'd.
B B B B - - - - ASSIST CONTROL MODE ASSIST CONTROL MODE
ASSIST CONTROL MODE ASSIST CONTROL MODE
In this mode the CROSSVENT-3+ will function either as an assist or controller. If the patient is inspiring,
the ventilator will sense the negative pressure created by the inspiratory effort and this will initiate an
assisted inspiration. If the patient fails to breathe, the ventilator will continue to give controlled breaths at
the backup rate as set by the main RATE setting.
Inspiration may be initiated by either a patient inspiratory effort or, in the absence of that, the backup
setting. At the start of inspiration, gas flows to the patient at the flow rate established by the FLOW
control, for the duration of the inspiratory time. Simultaneously, the exhalation valve is pressurized to the
Maximum Pressure level. The maximum pressure attainable is established by the MAXIMUM PRESSURE
control on the front of the ventilator. At the end of the inspiratory time, the patient gas flow is terminated
and zero or PEEP pressure is applied to the exhalation valve.
The SIGH function can only be used in the Assist Control and SIMV modes. During a SIGH breath, the
patient gas and Maximum Pressure remain on long enough to deliver the SIGH volume at the preset normal
flow rate. This is equivalent to 1.5 times the volume set while the I/E ratio of a sigh breath is maintained at
the same I/E ratio of a normal breath as set with the three primary controls: RATE, TIDAL VOLUME and
FLOW.
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