User manual

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Throughout the MMV, the ventilator always assesses the last 8 breaths and converts
their volume to the expected minute volume. This automatic regulatory process is functional
within the limit of 3 kPa over CPAP and within 5 kPa absolutely. In case of alarm, the
inspiratory pressure support remains constant until the cause of the alarm is cleared up and
removed.
In the MMV mode, the ventilator always reacts to the set-up of the inspiratory
assistance (P
insp
). Both the initial value and the minimum value are set. The actually applied
pressure support may be greater than the one that was set up, even in case of introducing
distension treatment with the aim to keep the lung sufficiently stretched. The user may
calculate the value of the set-up pressure support from the difference between the measured
maximum pressure and the CPAP value.
The pressure control ventilation PCV mode
In the PCV (pressure control ventilation) mode, the guiding quantities are the
inspiratory pressure and time. In the CMV and SIMV modes, the breathing volume (V
T
) is the
decisive parameter. The pressure volume in CMV may be set up all the way to the value of 99
cm of H
2
O. During the PCV cycle, the initial flow is rather high, which allows for a fast
increase of pressure to the pre-set value. Subsequently, the flow is regulated so that the
inspiratory pressure remains constant in the following course. Setting up the I:E ration, as
well as the inspiratory plateau and the expiratory time is the same as in (S)CMV or SIMV.
In the pressure control ventilation (PCV), there is pressure variation in such a way as
to achieve the predestined inspiratory time. The breathing volume is not preset and depends
on many factors, among else on the pressure gradient, the peak flow, the breath’s flow
characteristics, and last but not least on the compliance of the respiratory system and the
resistance of the airways. PCV is similar to the inspiratory assistance, but there is a difference
in the fact that PCV takes into account the pressure course in time. Pressure control
ventilation can be used as classical ventilator controlled ventilation (PCMV), or else in the
SIMV mode (PSIMV), where it determines the characteristics of the guided breath.
PSIMV is very similar to the SIMV mode. It is characteristic for the set-up of a certain
number of pressure controlled breathing cycles with the course’s time control. These breaths
are synchronized by means of a trigger with the patient’s spontaneous breathing activity.
Between these breaths, the patient may breathe spontaneously.
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