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Trigger and spontaneous
breathing times for
SIMV mode:
Example:
f
= 5 / min
IMV
f
= 10 / min
IPPV
1
1
∆T = –––– – –––– = –––––––– – ––––––––– = 6 s
f
f
5 per min
IMV
IPPV
From the diagram we can see that:
T
= 3.5 seconds and
Spont
T
= 2.5 seconds
Trigger
During the trigger time, the system checks whether
the airway pressure drops at least 1 mbar below the
pressure measured at the end of the expiration phase.
The mandatorily applied minute volume may increase
if an automatic ventilation stroke is applied at the
beginning of each trigger period!
The duration of a mandatory stroke plus the
spontaneous breathing time is calculated as follows:
1
–––– + T
=6 s + 3.5 s = 9.5 s
Spont
f
IPPV
This corresponds to a frequency of approx.
6 per minute and the applied minute volume increases
to 6 per minute * V
.
T
T
Trigger
T
[sec]
Spont
5
4
3
2
1
1
2
Maximum pause time
1
1
10 per min
Synchronized Intermittent Mandatory Ventilation
Example
3
4
5
6
Description
T
Spont
T
Trigger
∆T [sec]
7
8
9
181
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