Ventway Sparrow User Manual
Page 93 of 144
15.3. SIMV-PC
In SIMV-PC (Pressure Control ventilation), the patient’s tidal volume is
determined by setting upper and lower pressure levels, and is dependent
upon overall pulmonary compliance and resistance.
The user defines a number of mandatory breaths in which the ventilator
provides a constant pressure set during the inspiratory phase. The
inspiratory pressure, inspiratory time, rate and maximum delivered tidal
volume values are set by the operator (by selection of patient weight or
modification of parameters setup). A pressure control breath can be
initiated both by the ventilator (mandatory pressure control breath) and
by the patient (assist pressure control breath), during the complete
breathing cycle.
The mandatory breaths are synchronized with the patient’s own breathing
attempts. A patient-triggered mandatory breath can only be triggered
within a trigger window. If the expiration phase and with it the
spontaneous breathing time is shortened on account of synchronization,
the next expiration phase will be extended. This adaptation prevents a
change in the number of mandatory breaths (RR). If no independent
breathing attempt is detected during the trigger window, the machine-
triggered mandatory breath is applied. The mandatory tidal volume (VT)
results from the pressure difference between PEEP and PIP (Peak
Inspiratory Pressure), the lung mechanics and the breathing effort of the
patient. If the Resistance (R) or Compliance (C) of the lung changes during
the ventilation treatment, the supplied tidal volume (VT) and thus the
minute volume (MV) also vary. These values may exceed the predefined TV
(Tidal Volume) and MV (Minute Volume) settings initially performed by the
user.
During spontaneous breathing at PEEP level, the patient can be supported
using PS (Pressure Support).
Default PS level is identical to the initial PIP value, and may be modified.
Changing PS value will change the Tidal Volume supplied by the ventilator
during spontaneous breathing.
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