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3.5 PSV
Pressure Supported Ventilation
This is a pressure limited mode of ventilation in
which each breath is patient triggered and
supported. The breath is patient triggered, pressure
supported and patient terminated. The infant
therefore has control of the whole cycle, i.e. the
inspiratory time and frequency. This form of
ventilation is dependant on the use of a flow sensor
placed between the ET tube connector and the
patient circuit. Changes in flow or volume signal
detects spontaneous breathing.
The termination sensitivity is also user adjustable
from 0% - 50%.
Example: 5% termination sensitivity means that the
pressure support will terminate when the inspiratory
flow drops to 5% of the peak value. The level of
pressure support can be manually adjusted by use
of the PIP parameter control.
PSV can be used in the weaning process. Weaning
is achieved by reducing the support level as the
infant is able to make more effort.
In this mode all the patient's breath attempts are
pressure supported, but mechanical breaths are
delivered at the set parameters (Ti, PEEP and PIP)
when a patient effort is recognised.
The User sets the following:-
• Positive End Expired Pressure (PEEP)
• Peak Inspiratory Pressure (PIP)
• Maximum inspiratory Time (Max Ti)
• Backup breath rate (Backup)
• The flow termination sensitivity
• Apnoea alarm time (Only if backup breath rate is
9 breaths per minute or lower)*
• O
2
%
• Flow breath detection threshold (Trigger
Sensitivity) – The patient effort required for the
ventilator to recognise the breath
• High and low pressure alarm thresholds
• Tidal volume, high and low alarm thresholds
• Minute volume, high and low alarm thresholds
3.5.1 PSV with TTV
plus
(Targeted Tidal Volume)
This is as for basic PSV with Apnoea Support,
where the inspiratory pressure shall be controlled by
the ventilator to achieve the user set Vte (for
assisted breaths).
The User sets the following:-
• Enables Targeted Tidal Volume (TTV) and
selects volume to be delivered (Vte)
• Max PIP
• Max Ti
Note: If the user sets the termination
sensitivity to OFF the PSV mode behaves as
PTV.
*Note: PSV will continue to function as stated,
but with breath rates of 10 and above, Apnoea
alarms are de-activated. Backup rates of 10
BPM and above are deemed sufficient to
support the patient.
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