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Using SIMV
SIMV = Synchronized IntermittentMmandatory Ventilation
SIMV is a combination of mechanical ventilation and
spontaneous breathing, with spontaneous breathing
possible between mandatory ventilator breaths.
If the patient does not breathe spontaneously within a
certain time period, the ventilator automatically applies a
mechanical breath.
A 6 second trigger window is kept open when setting
low ventilation rates. This will guarantee a minimum
expiratory time of 0.5 seconds. The duration of the trigger
window decreases as the frequency of mechanical
breaths increases.
With synchronization, mechanical breaths are applied
during a trigger time window that is calculated to
coincide with the patient's inspiratory effort. The
frequency of the mechanical breaths remains constant.
Synchronization is briefly indicated by a star (*) in the
display.
For rates of 5 to 40 bpm:
The mechanical breaths and their time parameters are
determined by the ventilator rate set for SIMV/CPAP:
»Rate« setting
Effect
0
No mechanical breaths
(page 35)
5 to 18.5 bpm
Fixed inspiratory time = 1.3 s
18.5 to 40 bpm
Fixed I : E = 1 : 1.5
CPAP
Operation
Using SIMV
33
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