Pediatric emergency medicine trisk 4087 4087
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pneumothoraces, spontaneous pneumomediastinum tends to be found most often
in tall, thin, adolescent males. Pneumomediastinum is typically caused by
alveolar rupture (though air can also escape from the airways or gastrointestinal
tract), resulting in free air that tracks along the bronchovascular sheath and then
migrates centrally to the hilum and surrounding structures. It often dissects
through soft tissues and fascial planes and can be seen in the neck and chest. Most
of the time, due to this dissection into the soft tissues, there is no significant
buildup of pressure in the mediastinum. It is often found incidentally on chest
radiography. In extreme cases, however, the tension produced in the mediastinum
can be great enough to impair both circulation and ventilation. Although
extremely rare, this phenomenon is most likely to occur in a patient who is
receiving positive-pressure ventilation, which enhances escape of air from the
bronchial tree into the mediastinum (Fig. 124.6 A ).
Clinical Recognition
Pneumomediastinum is most commonly associated with asthma exacerbations,
but can also be identified in cases of Valsalva maneuver, severe cough,
barotrauma, forceful emesis, foreign-body aspiration, and inhalational drug use.
The predominant symptom is pleuritic chest pain, which may radiate and be
accompanied by dyspnea and/or dysphagia. Crepitus over the neck or upper
thorax may be appreciated on physical examination. Auscultation over the heart
may reveal Hamman sign, which is a crunching sound that may obscure the heart
sounds. In the rare cases of tension pneumomediastinum, patients may be in
severe distress with distended neck veins, tachypnea, and cyanosis. In the
majority of cases, however, severe distress should prompt consideration of
additional or alternative diagnoses since it is unusual in isolated spontaneous
pneumomediastinum.
Management
Pneumomediastinum is diagnosed on chest radiography, which demonstrates air
tracking around and outlining mediastinal structures on both frontal and lateral
views. Subcutaneous emphysema is often appreciated as well. These findings
may be quite subtle (Fig. 124.6 B ). Management of pneumomediastinum
depends largely on the suspected etiology. In the vast majority of cases of
spontaneous pneumomediastinum, conservative treatment with rest, observation,
and analgesia is appropriate since most of these self-resolve over several days.
Patients should be instructed to avoid activities like the Valsalva maneuver that
increase pulmonary pressure. If esophageal perforation is suspected due to an
