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During the time window, if patient effort is detected, either a Spontaneous or an Assist breath is delivered for the first effort. If the last breath delivered was Mandatory, then a Spontaneous breath is delivered for the first patient effort of the window. If the last breath delivered was an Assist or Spontaneous breath, then an Assist breath is delivered for the first patient effort of the window. Assist breaths deliver the prescribed Tidal Volume during inhalation and the PEEP setting during exhalation.
During the time window, if patient effort continues to be detected (after the first patient triggered breath), Spontaneous breaths are delivered for the remainder of the window. Spontaneous breaths deliver the prescribed Pressure Support setting above PEEP during inhalation and PEEP during exhalation. The figure below provides example breath patterns in SIMV mode.
Tidal Volume = 500 mL Breath Rate = 5 BPM Inspiratory Time = 3.0 seconds Pressure Support = 10 cm H2O PEEP= 6 cm H2O
1 = Pressure Supported |
| = Mandatory Window |
M | ||
Breath |
| = Spontaneous Window |
S |
2= Mandatory Breath
3= Assist Breath
PRESSURE | 12 seconds | 12 seconds |
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| SIMV Mode | |
| Enter SIMV mode |
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| 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | TIME |
Chapter 3 Modes, Features, and Alarms
