Where do you set the tidal volume?
Normal VTfor each breath in a newborn depends on their body weight in kg and
type of ventilator used. In general, aim for 4-7cc/kg, but depending on ventilator,
one may have to set the volume at 10 cc/kg.
This difference is due to where the different ventilators make their measurements
of exhaled tidal volume. The measurement may take place at the endotracheal
tube or at the ventilator. You may need to allow for dead space in the tubing.
Remember, in volume ventilation, the ventilator will use whatever pressure is
necessary to deliver that set volume of air. That means the pressure willvary
from breath to breath as the lung compliance changes, but the delivered
volume of air will always stay the same. (ie, for one breath, it might take a PIP
of 25 to deliver the set volume of air, and the next breath might only need a
PIP of 20). If a large leak is present, may be very difficult to use this mode of
ventilation.
This is actually a more physiologic way of ventilating the lung, and is used
frequently outside the NICU. However, caution should be used in the
premature, because their lung compliance changes rapidly. Ensuring that
alarm limits are appropriate and monitoring of pressures is very important.