return, as well as from shifting mediastinal structures (particularly in younger children) with compression of the cardiovascular structures Clinical Assessment The symptoms and signs of pneumothorax depend on the size of the pleural collection and how rapidly it occurs The most common presenting symptoms are unilateral chest pain and dyspnea For example, it is common for a patient with spontaneous rupture of an emphysematous bleb to complain of sudden acute pain on the involved side of the chest followed by tachypnea, pain at the tip of the ipsilateral shoulder, and a sense of shortness of breath Such patients usually have a small to moderate pneumothorax (less than 20% of the lung volume), often with no accompanying hypoxia Decreased breath sounds may be heard on the ipsilateral side, and a chest radiograph will usually demonstrate the pneumothorax, particularly if taken at end expiration Patients with a more longstanding pneumothorax may not even be in pain In general, a patient with a pneumothorax of 50% or more of the lung volume will exhibit signs and symptoms of ventilatory impairment: dyspnea, tachypnea, pain, splinting on the involved side, agitation, increased pulse rate, diminished breath sounds, and increased resonance to percussion on the involved side Displacement of the trachea and heart away from the involved side occurs in large pneumothoraces Severe dyspnea should alert the physician to the possibility of a very large or possible tension pneumothorax A child with existing underlying lung disease may display more severe symptoms and hypoxemia with a small or moderate pneumothorax In addition to describing symptoms, the patient with pneumothorax should be asked about potential predisposing conditions or risk factors including asthma, foreign-body aspiration, underlying infections, inhaled drug use, activities at onset of symptoms, and history of any prior pneumothoraces If the patient’s condition is not severe, an immediate upright PA and a lateral chest radiograph should be taken These radiographs are important to determine not only the site and extent of the pneumothorax but also any complicating features such as tumor, fluid within the pleural space, or abnormalities of the lungs, diaphragm, or mediastinum Management There are currently no widely accepted pediatric guidelines regarding management of spontaneous pneumothoraces Approaches may vary depending on the extent of the pneumothorax, the severity of symptoms, ongoing expansion, presence of tension physiology, and the suspected underlying etiology or clinical condition Small spontaneous pneumothoraces (e.g., less than 15% to 20% of lung volume) that are asymptomatic can typically be managed with prolonged observation alone, either in the ED or through admission to the hospital Pediatric patients with a pneumothorax require observation, even if no chest tube is believed necessary, to monitor for signs of clinical deterioration (e.g., hypoxia) and to repeat a chest radiograph as clinically indicated to ensure no progression of the process Limited evidence suggests supplemental oxygen may hasten the rate of pleural air absorption; patients with moderate to large pleural effusions are typically placed on a nonrebreathing facemask Patients with larger pneumothoraces, any hypoxemia or respiratory distress, or those with evidence of ongoing leak from the lung surface usually require intervention Options include thoracentesis, placement of a small “pigtail” catheter, or placement of a standard chest tube (see Chapter 130 Procedures ) In the ED, the percutaneous “pigtail” catheters are ideal for pneumothoraces without associated hemothorax or empyema However, these catheter devices are small gauge and may develop fibrin plugs Therefore, in a patient in whom continuous accumulation of air takes place in the pleural space despite the presence of a thoracentesis or pigtail catheter, a standard-sized chest tube should be placed A surgical consultation is generally warranted for any patient with a pneumothorax, particularly if there is evidence of a continuing air leak or the mechanism was traumatic, or due to an underlying anatomic abnormality Tension pneumothoraces are a life-threatening emergency and deserve special consideration A tension pneumothorax should be clinically obvious from absent breath sounds on the affected side, respiratory distress, hypoxia, and tracheal deviation These patients require immediate decompression with a large-bore (14gauge) angiocatheter into the second intercostal space anteriorly to evacuate the air and relieve the tension Treatment should not be delayed to obtain a chest radiograph The insertion of the needle and catheter will immediately result in release of the tension on the mediastinum and diaphragm This maneuver should be followed by the controlled placement of an appropriate-sized chest tube Depending on the suspected etiology, further studies such as CT may be indicated Definitive surgical therapy, such as VATS with pleurodesis, is typically reserved for patients who have recurrent spontaneous pneumothoraces, severe underlying lung disease, or a persistent air leak not responding to conventional chest tube drainage Unfortunately, at least half of children who suffer from a spontaneous pneumothorax will have a recurrence Pneumomediastinum Pneumomediastinum occurs when there is an abnormal collection of air in the mediastinum from either a spontaneous or traumatic mechanism As with 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 esophageal foreign body or a significant history of forceful emesis, an esophagram using water-soluble contrast may be helpful In the extremely rare case of a tension pneumomediastinum, evacuation of the accumulated air in the mediastinum is necessary FIGURE 124.6 A: Significant pneumomediastinum with accentuation of the cardiac silhouette B: A far more subtle pneumomediastinum in an asthmatic patient with chest pain Pleural Effusion Pleural fluid in excess amount is not a disease per se, but it indicates the presence of pulmonary or systemic illness The classification of the fluid into transudate , which accumulates when the normal pressure relationships between the capillary pressure in the lung, the pleural pressure, and the lymphatic drainage pressure are disturbed, or exudate , an inflammatory collection, has less utility today because of other diagnostic tools presently available Nevertheless, it is important to recognize causes of transudative fluid collections, including increased pulmonary capillary pressure (as in congestive heart failure), decreased colloid osmotic pressure (as in renal disease), increased intrapleural negative pressure (as in atelectasis), or impaired lymphatic drainage of the pleural space (e.g., from surgical trauma to the thoracic duct) In children, the inflammatory cause of effusion is most commonly a result of pneumonia, with accumulation of infected fluid in the pleural space, or empyema (see below) Malignant effusions from associated oncologic diagnoses are much less common than in adults, but also occur in children The accumulation of blood in the pleural space because of trauma is discussed in Chapter 115 Thoracic Trauma Hemothorax may also ...prolonged observation alone, either in the ED or through admission to the hospital Pediatric patients with a pneumothorax require observation, even if no chest tube is believed necessary,... traumatic, or due to an underlying anatomic abnormality Tension pneumothoraces are a life-threatening emergency and deserve special consideration A tension pneumothorax should be clinically obvious