NAVA study.

In this study we want to see if NAVA is applicable in the neonatal and pediatric patient. We want to investigate what fysiological differences there might be between NAVA and a conventional mode.

NAVA (neurally adjusted ventilatory assist) is a newform of artificial respiration, based on the electrical activity of the diafragma. We want to investigate wether there are fysiological differences between the conventional mode and NAVA.

1. Fysiological and respiratory parameters every minute;

2. Comfortscore every half our;

3. Position of catheter, when a chest X-ray is taken.

NAVA working mechanism:

NAVA stands for neurally adjusted ventilatory assist. This mode of
mechanical ventilation is based on the neural respiratory output from
the patient itself.
This new mode is only available on the Servo I, produced by Maquet Solna
Sweden.

The act of breathing depends on rhytmic discharge from the respiratory
center of the brain. This discharge travels along the phrenis nerve and
excites the diaphragm muscle cells. The diaphragm contracts and as a
result there is a pressure drop in the lungs causing air to flow into
the lungs.

Respiratory support is given on the basis of measurement of the
electrical excitation of the diafragm ( Edi signal). A naso-gastric
tube, wich has multiple electrode rings placed on the distal part of the
tube, is put in the proper position ( the electrodes will be placed at
diafragm level.). The electrical signal of the diafragm then can be
detected and a software program filters the signal from artefacts ( eg
the electrical excitation of the heart). The Edi signal is displayed on
the monitor of the Servo I.

Because both the patient and the machine act upon the same signal there
is an instantaneous support from the machine.

NAVA is synchronous with the patient's own respiratory frequency and the
support level is propotional too the magnitude of the Edi signal. This
means that if the signal is stronger the support will be higher and
vice-versa. This new mode of ventilatory support may give the patient
improved synchrony, lung protection and patient-comfort.


First we insert an Edi catheter, which measures the electricalsignal at diafrgam level.
Then we will observe the fysiological, respiratory parameters and take a comfortscore.