Kraig J. Lage (University of Missouri Hospital and Clinics / Columbia / MO / United States)  

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Male  

Newborn male (39 weeks gestation) who had a forceps assisted delivery secondary to nonreassuring fetal heart tones. At delivery, infant was cyanotic, had poor tone, and no cry. Infant was dried, warmed, suctioned, and stimulated without response. Bag/mask ventillation was administered with response of heart rate rising to greater than 100. Bag/mask ventillation was continued for one minute until spontaneous respirations. Infant continued to have increased work of breathing with flaring, retractions, and tachypnea. CPAP was continued with decreased work of breathing.  

Alveolar rupture is caused by a pressure gradient between the alveolus and the surrounding interstitium. The pressure gradient is a product of either hyperinflation of the alveolus or a decrease in the surrounding interstitial pressure.

The air forced into the interstitial tissues tracts centrally toward the peribronchial and perivascular tissue, and may continue into the mediastinum, neck and subcutaneous tissues.

Because not all alveoli are ruptured, adjacent normal alveoli cause an equalisation of pressure between the affected and damaged alveoli with the result that the interalveolar walls remain intact and the lungs inflated.  

<- view X-Ray 1

X-Ray 1: Large lucency surrounds the superior mediastinum with lucency crossing midline. Subtle lucency is also seen inferior and lateral of the right lung base at the costophrenic angle and hemidiaphragm.

<- view X-Ray 2

X-Ray 2: Large lucency surrounds the superior aspect of the anterior mediastinum with elevation of the thymic shadow.

Total constellation (Consens)  

N/A  

Pneumomediastinum occurs in approximately 0.1% of neonates and carries a good prognosis, typically without complications or long term sequella.

Factors predisposing to pneumomediastinum include pneumonia or meconium aspiration syndrome.

Neonatal pneumomediastinum can be attributable to pulmonary infection, immature lungs and ventilatory support. However, a significant portion of cases of spontaneous pneumomediastinum occur without identifiable risk factors.  

Diagnosis of pneumomediastinum is confirmed by frontal CXR.

Typical radiologic signs are:

1. In infants, the “spinnaker sign” which is upwards and outwards displacement of thymic lobes raised above the heart by pneumomediastinal air that separates it from the underlying cardiac silhouette.

2. "continuous diaphragm sign", visible as lucency interposed between the pericardium and the diaphragm.

3. Linear bands of mediastinal air parallelling the left side of the heart and the descending aorta with the pleura seen as a thin line separated from the mediastinum by the air lucency. The air may extend superiorly along the great vessels into the neck.  

Neonate presenting with respiratory distress.  

Doug Hacking, M.D., and Michael Stewart, M.D.
Neonatal Pneumomediastinum
N Engl J Med 2001 June 14; 344:1839

Annik Hauri-Hohl, Oskar Baenziger, and Bernhard Frey
Pneumomediastinum in the neonatal and paediatric intensive care unit
Eur J Pediatr. 2008 April; 167(4): 415–418

 

Thorax-Lung  

physical