Principles of Operation
126
Instructions for Use Oxylog 3000 SW 1.n
Ventilation modes
IPPV (CMV)
Intermittent Positive Pressure Ventilation
(Controlled Mandatory Ventilation
The ventilation pattern is specified by the settings
for tidal volume VT, frequency Freq., ventilation
time ratio I:E and PEEP.
At the end of the flow phase, the expiration valve
remains closed until the end of the inspiration time
Ti. This phase, the inspiratory pause, can be
identified as the plateau Tplat.
IPPVAssist (CMVAssist)
Assisted ventilation with continuous positive airway
pressure.
The mandatory ventilation stroke begins when the
patient reaches an inspiratory flow corresponding
at least to the set flow trigger.
The current ventilation respiratory rate may be
greater than the set respiratory rate for the same
trigger.
SIMV
Synchronized Intermittent Mandatory Ventilation
Combination of mandatory ventilation and
spontaneous breathing
SIMV enables the patient to breathe spontaneously
in regular prescribed cycles, with the mechanical
mandatory ventilation strokes providing a minimum
ventilation during the remaining cycles.
The minimum ventilation is controlled by the two set
values of the tidal volume VT and frequency Freq.
and is determined from the product of VT x Freq.
The ventilation pattern results from the ventilation
parameters of the tidal volume VT, frequency Freq.
and inspiration time Tinsp.
To prevent the mandatory ventilation stroke from
being applied during spontaneous expiration, the
flow trigger of the ventilator ensures that the
ventilation stroke is triggered in synchrony with the
patient's spontaneous inspiratory effort within a
"trigger window".
041
Paw
Flow
T
insp
T
e
T=
P
plat
1
t
t
PEEP
without plateauwith plateau
Freq.
T
plat
042
Paw
PEEP
t
Spontaneous
breathing time
Spontaneous
breathing time + T
Trigger
window
Synchronised
mandatory
ventilation stroke
Unsynchronised
mandatory
ventilation stroke
Tinsp
Freq.
1
Set mandatory
cycle time
Freq.
1
Set mandatory
cycle time
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