Acquired tracheomegaly in very preterm neonates
V. K. Bhutani, W. G. Ritchie and T. H. Shaffer
Proximal airways are compliant structures at early gestational ages and may
be susceptible to pressure-induced deformation following prolonged
ventilatory support. Sixteen neonates (mean +/- SD gestational age, 27.0
+/- 0.6 weeks; mean +/- SD birth weight, 847 +/- 68 g) were studied to
assess tracheal volume deformation. The neonates received ventilatory
support for a mean +/- SD duration of 25.4 +/- 4.9 days. During this period
the maximum peak inspiratory pressures ranged from 15 to 25 cm H2O, and
respirations ranged from 20/min to 60/min. These neonates were studied at
seven days postextubation and were individually matched for body weight
with 16 nonventilated neonates. The width of the tracheal air column was
measured at the lower border of the first thoracic (T-1) and third thoracic
(T-3) vertebrae. The average tracheal width (average of T-1 and T-3) was
significantly (38%) wider in the ventilated group, and the mean +/- SD
tracheal width values were 3.79 +/- 0.29 mm, as compared with the control
values of 2.74 +/- 0.31 mm. Based on these data it was estimated that the
tracheal volume was 91% greater in the ventilated group. These observations
demonstrate tracheal volume deformation and acquired tracheomegaly in
neonates who have received mechanical ventilatory support. In addition to
increased dead space ventilation, these findings also indicate underlying
mechanical deformation of the tracheal wall.
