NAVA on the PICU and NICU: Feasibility study with children needing mechanical ventilation

Modes of partial ventilatory assistance are preferred to reduce side-effects
and complications associated with controlled mechanical ventilation. With these
modes, ventilator cycling is ideally under control of the patient*s own
respiratory drive and rhythm, which also influences the ventilatory output to
an extent that varies with the different modes. Coordination between
spontaneous breathing and mechanical assistance, however , is not guaranteed
and a poor interaction between patient and machine may represent a major
problem in the ventilatory management of patients with acute respiratory
failure. Neurally adjusted ventilatory assist (NAVA), introduced by MAQUET in
2007, is a new form of partial support wherein the machine applies positive
pressure throughout inspiration in proportion to the electrical activity of the
diaphragm (EAdi) as assessed by trans-esophageal electromyography. The amount
of assistance for a given EAdi depends on a usercontrolled gain factor. With
intact phrenic nerves, EAdi is the earliest and best signal available to
estimate the neural respiratory drive. Because ventilator functioning and
cycling are under control of the patient*s respiratory drive and rhythm, NAVA
has the potential to enhance patient-ventilator interaction ensuring synchrony
and minimizing the risk of over-assistance. The first experimental studies with
NAVA seems to confirm this.
Which patient categories gains the best benefit with NAVA needs to be studied.
One of the main benefits should be improved patient-ventilator
synchronization. Altogether, we can expect patients experience greater
respiratory comfort*even those at risk of dynamic hyperinflation. There is less
experience with NAVA in children, so there is a need for research : Does NAVA
have clinical benefits for ventilated children in comparison to conventional
ventilation? In this study we first want to know if NAVA is feasible to use in
children with uncomplicated mechanical ventilation.

Feasibility study of the option NAVA (Neurally adjusted ventilatory assist) on
the Servo-i in ventilated children in the age of 0-18 on the PICU and the NICU
of the Erasmus MC -Sophia Childrens hospital in Rotterdam.

Design
Prospectif observational pilot study with intervention

NAVA
First we measure for 3 hours without NAVA with the Edicatheter. After 3 hours
we measure with NAVA. The intervention is to activate NAVA and to observe what
is happening.

There are no direct advantages for the child. Later when we have measured
enough parameters we know if NAVA can be used for quicker weaning and more
comfort. The results of the research is important for the future. Other
children will experience the profit of NAVA. A possible disadvantage for the
child can be that a enteral feeding tube that already is in situ will be
changed by a Edi catheter which can measure the electrical signals. However the
feeding tube would be changed on a regular base, according to the protocol of
feeding tubes.
After the child receives the NAVA feeding tube the electrical signal will be
measured. To make a comparison between the two methods we want to measure 3
hours with the conventional ventilation. Afterwards we will measure 3 hours
with NAVA ventilation. In this second period the machine will react on the
electrical signal of the diaphragm. During this period there will be a
researcher near the child for the whole time of measuring. If the child will
stay for a longer period on the ventilator we will ask the parents for another
6 hours of measuring. Two times 6 hours is the maximum. The Edi catheter will
be in situ until the child no longer needs a feeding tube or until the feeding
tube needs to be replaced according the policy of the ward.
There will be no risks if the stop criteria will be used properly, an hour
after starting NAVA. If the patient worsens in relation to the conventional
ventilation we use the next stop criteria:
- Inspiration pressure > 25 cm H20 for NICU and > 35 cm H2O for PICU
- Breathing frequency > 80-100 / min
- Raising of the EtC02 > 2Kpa in comparison to the Et CO2 during conventional
ventilation
- Discomfort in children (PICU): COMFORT score >=23 or COMFORT score 11-22 and
VISS = 1 (insufficient sedation)
- Discomfort in neonates (NICU): COMFORT Neo score >= 14.