6-9
6.5.3 V-A/C
V-A/C is volume-assist/control ventilation mode. In V-A/C mode, a certain tidal volume is
delivered to the patient within a certain period of gas delivery time. During the expiratory
phase, V-A/C mode supports synchronization trigger. Namely, when the ventilator detects
patient inspiratory effort, it delivers next mechanical ventilation in advance.
The following figure shows typical waveforms in V-A/C mode. Pmax stands for high alarm
limit of Paw.
Pmax-5
Pmax
PEEP
Tpause(%)×Tinsp
Paw
Flow
t
t
Tinsp
Texp
1/f
Insp. trigger
level
Insp. trigger level
In V-A/C mode, you need to set the following ventilation parameters:
1. [O
2
%]: Oxygen concentration
2. [TV]: Tidal volume
3. [Tinsp] or [I:E]: Inspiration time or ratio of inspiratory time to expiratory
time
4. [f]: Breathing frequency
5 [PEEP]: Positive end-expiratory pressure
6. [Assist]: Switching trigger ON/OFF
7. [F-Trig] or [P-Trig]: Inspiration trigger level
8. [Tpause(%)]: Percent of inspiratory pause time
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