Stephan EVETR, Instructions For Use Manual, Page: 147 / 254

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7 Ventilation modes
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Fritz Stephan GmbH GA-070T-0518V2.7-HAO-EN 147
The trigger is only active within a so-called trigger expectation window.
The length of this expectation window and the time gap between the
windows vary depending on the set expiration time.
The expiration time is divided into two phases.
In the first phase (Texp
spon
= 50% of Texp), the patient can only breathe
spontaneously. Even when the trigger threshold is crossed, there is no
mandatory support from the ventilator. If the patient breathes
spontaneously during the second phase of the expiration time, the
EVE
TR
now delivers a mandatory breath.
Selecting the inspiration and expiration time or frequency lets the user
specify a mandatory base frequency that does not change. It applies even
if the patient exhibits active spontaneous breathing that could
theoretically trigger a lot more mandatory breaths. As a result, the time
by which the expiration time was reduced is added to the next following
expiration times after each trigger event. This means that the average
matches the mandatory base frequency set by the user.
The actual total breathing frequency is shown in the "ftotal" measured
value display of the monitor. This also shows the minute volume
measurement as "MVtotal".
Fig. 84: VC-SIMV