Pediatric emergency medicine trisk 4071 4071
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breathing, cyanosis, and respiratory failure. In addition to medical management,
they may benefit from noninvasive or invasive ventilatory strategies. The subset
of children with severe disease resulting in recurrent bouts of respiratory failure
may require tracheal surgery or placement of a tracheal stent.
Vascular Rings
Vascular rings represent a rare and varied group of developmental anomalies of
the aorta and great vessels. They may produce obstruction of the esophagus,
trachea, or both. These rings are a result of failure of the normal involution of the
appropriate segments of the six embryologic aortic arches. Vascular rings are
characterized as complete when both the esophagus and trachea are fully
encircled and incomplete when they are only partially encircled. Complete rings
are typically caused by a double aortic arch or a right-sided aortic arch with an
aberrant left subclavian artery and left ductus arteriosus or ligamentum.
Incomplete rings are often caused by a pulmonary artery sling, innominate artery
compression, or an aberrant right subclavian artery. The level of respiratory
obstruction is usually the trachea, but compression of a bronchus by the ductus
arteriosus or by a pulmonary artery sling, may produce compression more
distally.
Clinical Recognition
Vascular rings may be asymptomatic in infancy but lead to significant airway
obstruction in childhood. The wide variety of anomalies produces varying
degrees of symptoms. Presentations range from incidental findings on imaging
studies to neonates with critical airways. Vascular rings should be suspected in
infants with stridor, dysphagia, failure to thrive associated with difficult feeding,
or recurrent pneumonia. Esophageal obstruction can produce difficulty
swallowing. A patient with esophageal compression may also have respiratory
symptoms from compression on the trachea from a distended esophageal pouch.
This may lead to reflex apnea during feeding, and eventually tracheomalacia in a
more chronic setting.
Often, diagnosis is delayed by failure to consider these anatomic obstructions
since their presentation can be quite varied and subtle. In a patient presenting with
an acute airway obstruction or other medical problems requiring intubation and
nasogastric tube placement, detection of a vascular ring can be even more
difficult because of the presence of these tubes. Chest radiographs are the initial
test of choice and suggestive findings include an abnormal-appearing aortic knob
or deviation of the trachea or esophagus. Chest radiographs may be supplemented
by various diagnostic tests: contrast esophagography (e.g., barium swallow),
