Ministry of Health
pneumothorax may be seen as an isolated finding in an infant with
respiratory distress, or may be associated with other forms of lung disease
(particularly RDS and MAS). The findings can be subtle with just
minimal differences in lucency of lung fields.
Pneumothorax in a ventilated
infant may be an emergency if it is under tension. In the
circumstance (as shown in the top image), urgent drainage prior to a
radiograph is indicated.
Risk factors for pneumothoraces
However, up to 2% of infants
can develop spontaneous pneumothoraces at birth. These are thought
to be secondary to the high pressures that infants can generate
themselves when initiating breathing. Many infants have minimal or
no symptoms and the air leak resolves spontaneously over time.
The administration of 100% oxygen
to term infants ("nitrogen washout") is said to potentially resolve the
pneumothorax more rapidly. The theory is that nitrogen in the air
contained in the pleural space passively diffuses across lung into alveoli
full of 100% oxygen. This encourages resolution of the intrapleural
air leak. It is said that if this treatment is given, the pneumothorax
will resolve in 48 hours instead of the 2 days it will take if you just
leave it alone (.... think about it).
images to the left are from a term infant born by caesarean section at term.
The baby had respiratory difficulty from birth but no resuscitation (that
is, bagging) was needed other than some mask oxygen.
An initial radiograph showed
bilateral pneumothoraces (top image). The outline of the right
lung is seen clearly. The left pneumonthorax is more subtle. The
baby had bilateral chest drains inserted and required ventilation.
The second radiograph shows
bilateral intercostal drains. The tip of the left drain is kinked.
The lung fields are not well inflated despite high airway pressures at
the time. This baby has significant pulmonary hypoplasia.
images are of a preterm infant born at 24 weeks whose ventilation
requirements increased on the second day of life. Transillumination
was not diagnostic, perhaps because there was no asymmetry due to the
bilateral pneumothoraces. A chest radiograph demonstrated a large
tension pneumothorax on the right side, and a smaller air leak on the left.
Chest drains was inserted and
the baby clinically improved. Note that the right sided drain was
inserted too far (note: in small babies, it is all too easy to insert
the drains too far).
In a small infant such as this, a
head ultrasound scan should be performed
to determine whether any deterioration at the time of the pneumothoraces was
associated with intraventricular haemorrhage.
Pulmonary Interstitial Emphysema
Pulmonary interstitial emphysema (PIE) is most commonly seen in small
infants with significant RDS. There are microscopic air leaks, with
air tracking along the interstitium of the lung. Pneumothorax is a
common association, and Chronic Lung Disease is also a common sequelae.
The radiographic appearance may be described as "salt and pepper".
If the PIE is localised to one
side, the infant can be nursed with that side "down". Occasionally,
selective intubation of the unaffected lung can be performed to "rest" the
Occasionally, ongoing air leaks
occur which result in localised collections of air within the lung
parenchyma. The initial radiograph of this 23 week infant on day
one demonstrates a localised area of PIE in the right lower lobe.
area increased over the next few days,
increase in size ...
until it was large enough to
compress the right upper lobe and cause mediastinal shift to the left.
Strategies have been proposed
to treat this, including selective bronchus intubation to aerate the
"good" lung, and there are reports of aggressive surgical resection of
the affected lobe.
Tuesday, 29 November 2011