Section 5 - Operation
AV2+ Anesthesia Ventilator
Setting the
Inspiratory/
Expiratory (I:E)
Phase Time Ratio
Use the I:E ratio control knob to set the inspiratory/expiratory (I:E)
phase time ratio. The standard range of ratios is from 1:1 through 1:4.5,
adjustable in increments of 0.5.
An extended range of ratios is also available which allows the setting of
inverse I:E ratios. The specific extended range settings are: 4:1, 3:1, and
2:1. The extended range settings are accessible by pressing the
EXTENDED RANGE switch while rotating the I:E ratio control knob.
Clockwise rotation of the control knob increases the I:E ratio setting,
while counterclockwise rotation decreases the I:E ratio setting.
WARNING: The use of inverse I:E ratios will introduce auto-PEEP.
Setting the
Inspiratory Flow
Rate
Use the inspiratory flow control knob to set the inspiratory flow in the
range of 10 l/min to 100 l/min. This setting controls the flow rate of gas
into the bellows canister, and thus the flow rate of gas delivered to the
patient.
Because of patient circuit variables such as lung compliance, fresh gas
flow, airway resistance and equipment compliance, the flow gauge is
labeled with nominal zones of LOW, MEDIUM, and HIGH.
You should adjust the flow setting to a point where the ventilator
bellows is fully compressed (but not deformed) at the end of the
inspiratory phase of the breathing cycle.
You can also use the inspiratory flow control to create an inspiratory
plateau at the end of the inspiratory cycle and to affect the potential
peak inspiratory pressure within the patient breathing system. Always
check the pressure indicated by the breathing system pressure gauge
and waveform when adjusting the inspiratory flow control.
Setting the
Inspiratory Pressure
Limit
The pressure limit control, located above the bellows canister, is used to
adjust the pressure limit. Nominal pressure zones are indicated by the
label. This control determines the maximum pressure that can be
delivered by the ventilator during the inspiratory phase of the
respiratory cycle. Because of patient circuit variables, the scale on the
label is only a reference; the pressure should be read from the breathing
system pressure gauge or the anesthesia machine’s pressure monitoring
system.
When the pressure limit control is turned fully counterclockwise, the
peak inspiratory pressure will be less than or equal to 15 cmH
2
O. When
the control is turned fully clockwise, the peak inspiratory pressure will
be less than or equal to 120 cmH
2
O.
5-8-5
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