Low rate intermittent mandatory ventilation (IMV) in the neonate

The effect of each IMV breath is to increase FRC, most likely by opening atelectatic areas of the lung. This same observation of an increase in FRC following a large tidal volume breath has been described in the normal neonate with spontaneous sighs. The decrease in tidal volume post ventilator breath has also been seen in normal neonates after lung inflation. Studies in adults have reported an increase in dynamic compliance (C(L)) after deep breaths however with the degree of pulmonary instability seen in the patients described here the variability of C(L), inspiratory and expiratory resistance is not surprising. This study suggests that in small neonates with unstable lungs each IMV breath increases FRC, thus maintaining a more normal lung volume.