Ministry of Health
Conventional Ventilation Modes
|Reviewed by Carl Kuschel
What is the difference between ventilation
There are essentially three types
of respiratory support provided in NICU.
(continuous positive airway pressure) is our first line mode of support for
infants with respiratory distress from any cause. The use of early CPAP is
effective in reducing the need for ventilation and surfactant in preterm infants
with respiratory distress syndrome, as well as being an effective mode of
ventilation for transient tachypnoea of the newborn and meconium aspiration
syndrome in term and near term infants. An added advantage is that it is also an
effective treatment for apnoea.
Other types of assisted ventilation
include positive pressure ventilation ("conventional" ventilation) and
high frequency oscillation ventilation (HFOV). The specialist on duty will
almost always initiate HFOV after assessment of an infant with severe
respiratory failure. A
is available which gives some basic information on how to ventilate infants in
Conventional ventilation is however
now more complex because there are many different ventilator modes. Many of them
have different names for the same sort of process. Our first-line ventilator is
the Drager Babylog 8000plus, which is both a conventional ventilator but
is also able to oscillate smaller infants. We also use VIP-Bird
ventilators as a second line.
We have a SensorMedics 3100 High
Frequency Oscillatory Ventilator which is generally reserved for infants who
have respiratory failure despite increasing "conventional" support. This
ventilator is not able to provide conventional ventilation.
The terminology for ventilation
modes is confusing and it is fundamental to understand the differences between
them in order to use the best mode for the baby. It also helps to have a basic
understanding of respiratory function monitoring.
In all scenarios below, the
ventilator is assumed to have a set up with:
Peak Inspiratory Pressure
Positive End Expiratory
These are the default settings on
SIMV for all babies ventilated on admission to the NICU. Different settings may
be ordered according to the amount of support the baby needs.
The default terminology is that of
the Babylog. If the same mode is available on the VIP-Bird with a different
name, this is noted.
(Intermittent Positive Pressure Ventilation)
60 breaths, one second apart
are given by the ventilator, irrespective of the baby’s own breathing. A
PIP of 15 is applied, with a PEEP of 5. The Ti is 0.35
(Synchronised Intermittent Mandatory Ventilation)
This is the preferred
60 ventilator breaths are delivered -
synchronised with the baby’s breath. If the baby is breathing faster
than 60 bpm, only 60 ventilator breaths are delivered and any additional
breaths are not assisted. The Ti is 0.35 seconds. If the baby
is not breathing, breaths will usually be delivered 1 second apart. If
the baby takes less than 60 breaths per minute, the ventilator will
synchronise all the breaths, plus deliver some untriggered breaths.
(Synchronised Intermittent Positive Pressure Ventilation)
(Assist Control, AC, on the
Every breath is assisted, but
the baby receives a minimum of 60 bpm. If the baby breathes at 100 bpm,
then the baby receives 100 assisted breaths. The PIP is 15, the PEEP is
5, and the Ti is 0.35 seconds.
(Note: on the VIP-Bird, applying
termination sensitivity (see
below) in this mode limits the Ti
Pressure Support Ventilation, PSV).
Note: it is important that the Ti
is watched carefully in this mode – too long a set Ti in an
infant with tachypnoea will result in a short expiratory time (Te)
and will result in air trapping, with the risk of air leak. PSV (see
below) is a safer mode.
(Pressure Support Ventilation)
Like SIPPV, all breaths are
assisted with a default minimum rate of 60. A PIP of 15 is still
delivered, the PEEP is still 5, but the Ti is limited
according to the baby’s own lung inflation (i.e. as the lungs fill up,
the breath is terminated). This means that the baby is controlling the
duration of breaths according to the lung mechanics. It is a safer mode
than SIPPV in that air trapping and a resultant leak are unlikely.
In the VIP-Bird, this mode is
achieved by setting the "termination
sensitivity". This is
set as a percentage of the peak inspiratory flow rate - as the lungs
reach full inflation, flow rate decreases. The default is to set it to
10% of the peak flow rate. This does not work well on the VIP-Bird if
there is a large leak.
This mode is available only
on the Babylog. In this mode, the ventilator is asked to deliver a
certain expired tidal volume (VT) – usually 4-8ml/kg breath.
The ventilator will look at the previous breath and deliver the
appropriate amount of PIP to deliver this volume. A maximum PIP is set –
if the ventilator cannot deliver the appropriate VT, the
ventilator will alarm. This mode does not work if there is a big
leak as the expired VT will be under-reading.
It is important to set up the ventilator
appropriately. See the associated webpage on
This mode is best delivered
with PSV or with SIPPV. This mode can create a lot of alarm messages so
patient choice and appropriate settings are important (see