Heyer iTernIS ADV, Operator'S Manual

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Basic operations | iTernIS ADV
6. 12
Sensitivity by pressure
In sensitivity by pressure, the inspiratory trigger is produced when a decline
in pressure greater than what is selected for sensitivity is detected in the
respiratory circuit during the expiratory phase.
NOTE
• The default inspiratory sensitivity for all modes
is by flow. The values depend on the category
of patient being ventilated. If a nebulization ma-
neuver is enabled, the detection automatically
changes to sensitivity by pressure.
• TIDAL VOLUME (VT): also known as current volume, it represents the volume
delivered by the ventilator in each breath. Among the monitored parameters there
is one with the same name that represents the volume exhaled by the patient in
each breath.
• FLOW WAVEFORM: this parameter determines the shape of the flow wave with
which the ventilator delivers the set volume. There are two possibilities for confi -
guring this parameter:
Descending ramp flow waveform
The descending ramp flow wave begins at the calculated peak flow value
and makes a linear decline to zero. In response to this decelerated flow, the
pressure and volume curves are similar to those in the pressure controlled
mode (PCV). However, in modes controlled by volume; the flow descent
is calculated and respected regardless of the mechanics of the patient’s
respiratory system. In PCV, the flow descent is the result of respiratory im -
pedance through which the flows travel. In VCV, the preset flow wave is a
descending ramp.
Fig. 6-8 Image of the
pressure, volume and flow
curves generated when
using the descending ramp
flow waveform.
Constant Flow Wave
A constant flow produces a rectangular wave. The flow quickly reaches
its maximum value and keeps it until the delivery of the selected volume
is completed. During the inspiratory phase, the pressure developed in the
airway shows two segments. The first has an initial quick rise due to the
abrupt pressurization of the tubes by the continuous flow and is considered
to be a reflection of the system resistive properties (resistance x flow). The
second segment has a less pronounced but progressive rise and depends
on the flow derived from the inspiratory time and the regulated volume,
representing the system elastic properties. The pressure continues to rise
until the end of the breath, which coincides with the cessation of the flow.
6.6.2 | Control or Support
Pressure