Anemia of Prematurity - Portal Neonatal

Table 3. High I/E Ratio/Long Inspiratory Time
Pros Cons
Increased oxygenation Gas trapping/inadvertent positive end-expiratory
pressure
May improve gas distribution in lungs
with atelectasis
Increased risk of volutrauma and air leaks
Impaired venous return
Increased pulmonary vascular resistance
Table 4. Short Inspiratory Time
Pros Cons
Faster weaning Insufficient tidal volume
Decreased risk for pneumothorax May need high flow rates
Allows use of higher ventilator rate
PICTURES Section 10 of 11
Picture 1. Relationships among ventilator-controlled variables (shaded circles) and pulmonary
mechanics (unshaded circles) that determine minute ventilation during pressure-limited time-cycled
ventilation. The relationships between the circles joined by solid lines are described by simple
mathematical equations. The dashed lines represent relationships that cannot be calculated
precisely without considering other variable such as pulmonary mechanics. Thus, simple
mathematical equations determine the time constant of the lungs, the pressure gradient, and the
inspiratory time. In turn, these determine the delivered tidal volume, which, when multiplied by the
respiratory frequency, provides the minute ventilation. Alveolar ventilation can be calculated from the
product of tidal volume and frequency when dead space is subtracted from the former (Adapted from
Chatburn RL, Lough MD).