ResMed Elisee 350, Clinical Manual

Page: 33 / 110

27/102 Ventilation
NOT013281-8
Inspiratory phase
The beginning of each cycle is triggered by the patient (through the flow or pressure trigger) or
by the user (by pressing the Manual breath button).
In PS.V
T
mode, you can set an apnea time , at the end of which the ventilator switches to apnea
ventilation if the patient does not trigger a cycle. This apnea ventilation may be either pressure-
controlled or volume-controlled, depending on the setting option selected.
Exiting apnea ventilation:
During apnea ventilation, the patient can trigger additional assisted controlled ventilation cycles.
On the fourth consecutive patient-triggered cycle, the ventilator returns to pressure support
mode.
The delivered cycle begins with pressure support ventilation. The Elisée 350 constantly
calculates, from the V
T
already delivered and the inspiratory time remaining, whether the target
minimum tidal volume (V
T
) will be able to be delivered.
•
If so, the Elisée 350 continues to deliver the cycle with pressure support.
•
If not, the ventilator switches to volume-controlled mode, delivering the remaining portion
of the tidal volume while maintaining an appropriate constant flow until the target minimum
tidal volume is reached. Switching to volume-controlled mode means that the set pressure
will be exceeded during that cycle in order for the minimum tidal volume to be delivered.
The pressure cannot be exceeded by a value greater than the Pmax alarm setting.
Note:
For optimum patient comfort, the minimum V
T
should be set to a lower value than the V
TE
recorded in Pressure Support mode. If it is set too close to the V
TE
value, the volume-controlled
part of PS.V
T
will be triggered too frequently. However, you may disregard this rule if the benefit
to the patient of a higher minimum V
T
outweighs the importance of patient comfort.
P
V
V
VTI>VT VTI>VT VTI>VT
t
t
t
The target minimum tidal volume is delivered
through pressure support alone, without a
switch to the volume-controlled part of PS.V
T
mode. The inspiratory flow progressively
reduces until the expiratory trigger threshold is
reached.
1 2
A
B
I E E I
P
Pm a x
V
V
t
t
t
VTI = VT VTI = VT
Zone A: Peak pressure rising above the target
pressure
Zone B: Phase during which the flow is
maintained at a constant level until the end of
the Ti
“Volume-controlled” phase (period between
the two red lines)
Based on the pressure support and Ti Max
settings, the ventilator detects, during the
cycle, that the minimum tidal volume cannot
be delivered. It therefore switches to volume-
controlled mode and delivers a constant flow
until the Ti Max is reached.