Stephan EVETR, Instructions For Use Manual, Page: 143 / 254

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7 Ventilation modes
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Fritz Stephan GmbH GA-070T-0518V2.7-HAO-EN 143
7.3 Mandatory ventilation
CMV (controlled mandatory ventilation) means that the ventilator
completely manages the breathing process. The patient has no influence
on ventilation.
Mandatory ventilation "forces" insufflation of the lungs for a preset
inspiration time (Tinsp). During this inspiration time, an inspiratory tidal
volume (VT) is provided to sustain the exchange of gas within the lungs.
At the end of the inspiration time (Tinsp), the ventilator switches to a
preset expiration time (Texp). The elastic restoring forces of the lung are
now responsible for passive expiration, during which pressure between
the lungs and ventilator is equalized. The exhaled expiratory breathing
volume is called the tidal volume and measured by the flow sensor (PNT)
and shown on the display.
The ventilation rate within one minute is called breathing frequency. The
patient’s spontaneous breathing is not hindered during the expiration
time, although the ventilator is not synced with the patient’s spontaneous
breathing.
During invasive mandatory ventilation, the patient has a virtually
"pressure-tight" connection to the ventilator through the endotracheal
tube (ETT) and the tube system. His breathing therefore depends on the
flexibility and efficiency of the ventilator. The ETT positioned in the
intubated patient's trachea prevents him from breathing. The smaller the
diameter of the ETT, the more difficult it is to breathe in and out.