respiratory pattern and volumes/pressures).The SIMV rate is the rate of the mandatory breaths
per minute.
The spontaneous/pressure-supported breath is defined by setting the Pressure Support level
above PEEP. When the user gradually decreases the SIMV rate, the patient has more and more
time for the spontaneous/pressure-supported breaths.
The SIMV algorithm is designed to guarantee one mandatory breath each SIMV breath cycle. This
mandatory breath is either a patient-initiated mandatory (PIM) breath (also called an
assisted
breath) or a ventilator-initiated mandatory (VIM) breath (in case the patient's inspiratory effort is
not sensed within the breath cycle).
As Figure 4-15 shows, each SIMV breath cycle (Tb) has two parts: the first part of the cycle is the
mandatory interval (Tm) and is reserved for a PIM. If a PIM is delivered, the Tm interval ends and
the ventilator switches to the second part of the cycle, the spontaneous interval (Ts), which is
reserved for spontaneous breathing throughout the remainder of the breath cycle. At the end of an
SIMV breath cycle, the cycle repeats. If a PIM is not delivered, the ventilator delivers a VIM at
the end of the mandatory interval, then switches to the spontaneous interval.
Figure 6-14
SIMV breath cycle
There are three different SIMV modes:
⚫
SIMV (VC) + Pressure Support
⚫
SIMV (PC) + Pressure Support
⚫
SIMV (PRVC) + Pressure Support
6.5.5.2 Start SIMV Mode
You can select [SIMV-VC], [SIMV-PC] or [SIMV-PRVC] as required.
To start SIMV-VC mode, do as follows:
1. Push the [Modes] button to open the [Modes] menu.
2. Push [SIMV-VC] in the [Modes] menu, then the [controls] menu for SIMV-VC mode is opened.
3. Adjust appropriately parameter settings for the patient and then confirm the settings to start
SIMV-VC mode.
To start SIMV-PC or SIMV-PRVC mode, take the above description as an example.
6.5.5.3 Parameter Setup Area in SIMV Mode
When SIMV mode is confirmed, Key parameters is automatically switched over to the parameter
setup area in this mode. It is convenient to monitor and set.
⚫
The following figure shows these parameters to be set in SIMV-VC mode.