Pectus Excavatum

Sternal concavity (pectus excavatum) is a common chest wall deformity in children, and is usually not associated with significant pulmonary compromise. However, occasionally, if severe, it can result in restrictive lung disease and decreased right-sided heart output. Often it comes to attention because of concerns over the appearance of the chest (cosmetic reasons). Adolescents with pectus excavatum may complain of exercise intolerance, and formal exercise testing may be indicated. Routine spirometry is often normal but may show a decreased vital capacity consistent with restrictive lung disease. The main reason for surgical correction is to improve appearance (cosmetic reasons), although in some cases surgical repair is justified to improve cardiac output and exercise tolerance. Surgical correction is best done during young adolescence before the bones have achieved full skeletal maturity. Surgical repair may improve exercise tolerance, but it does not improve lung function.

Pectus Carinatum

Pectus carinatum is an abnormality of chest wall shape in which the sternum bows out. It is not associated with abnormal pulmonary function. However, underlying pulmonary disease may contribute to the deformity, and it can be observed after open heart surgery performed via midsternal approaches. Surgical correction of this condition is rarely indicated, but occasionally it is done for cosmetic purposes.

Etiology

Pneumothorax, which is the accumulation of air in the pleural space, may result from external trauma or from leakage of air from the lungs or airways. Spontaneous primary pneumothorax (no underlying cause) occurs in teenagers and young adults, more commonly in tall, thin males and smokers. Factors predisposing to secondary pneumothorax (underlying cause identified) include barotrauma from mechanical ventilation, asthma, cystic fibrosis, trauma to the chest, and severe necrotizing pneumonia.

Clinical Manifestations

The most common signs and symptoms of pneumothorax are chest and shoulder pain and dyspnea. If the pneumothorax is large and compresses functional lung (tension peumothorax), then severe respiratory distress and cyanosis may be present. Subcutaneous emphysema may result when the air leak communicates with the mediastinum. Physical findings associated with pneumothorax include decreased breath sounds on the affected side, a tympanitic percussion note, and evidence of mediastinal shift (deviation of the PMI and trachea away from the side of the pneumothorax) (see Table 133-3). If the pneumothorax is small, then there may be few or no clinical findings. However, the patient’s clinical condition can deteriorate rapidly if the pneumothorax expands and especially if the air in the pleural space is under pressure (tension pneumothorax). This is a life-threatening condition that can result in death if the pleural space is not decompressed by evacuation of the pleural air.

Diagnostic Studies

The presence of a pneumothorax can usually be confirmed by chest radiographs. Computed tomography (CT) scans of the chest are useful in quantifying the size of pneumothoraces and differentiating air within the lung parenchyma (cystic lung disease) from air in the pleural space. In infants, transillumination of the chest wall may be of some use in making a rapid diagnosis of pneumothorax.

Treatment

The type of intervention depends on the size of the pneumothorax and the nature of the underlying disease. Small pneumothoraces (<20% of thorax occupied with pleural air) may not require intervention as they often resolve spontaneously. Inhaling high concentrations of supplemental O₂ may enhance reabsorption of pleural air by washing out nitrogen from the blood, thus establishing a higher nitrogen pressure gradient between pleural air and the blood. Larger pneumothoraces and any tension pneumothorax require immediate drainage of the air, preferably via chest tube. In an emergency situation, a simple needle aspiration may suffice, though placement of a chest tube is often required for resolution. In patients with recurrent or persistent pneumothoraces, sclerosing the pleural surfaces to obliterate the pleural space (pleurodesis) may be necessary. This can be done either chemically, by instilling talc or sclerosis agents (doxycycline) through the chest tube or by surgical abradement. Surgical approaches, open thoracotomy and video-assisted thoracoscopic surgery (VATS), enable visualization of the pleural space and resection of pleural blebs, when indicated.

Etiology

Fluid accumulates in the pleural space when the local hydrostatic forces that are pushing fluid out of the vascular space exceed the oncotic forces that are drawing fluid back into the vascular space. Pleural effusions can be transudates (intact membrane but abnormal hydrostatic or oncotic forces) or exudates (decreased integrity of the membrane primarily due to inflammatory processes). There are relatively few causes of transudates, the primary ones being congestive heart failure and hypoproteinemia states, while the causes of exudates are legion. Almost any pulmonary inflammatory process can result in pleural fluid accumulation. Among the most common causes of exudates are infection (tuberculosis [TB], bacterial pneumonia), collagen vascular diseases (systemic lupus erythematosus), and malignancy. Chylous pleural effusions (elevated triglyceride levels) are seen with thoracic duct injury (thoracic surgery, chest trauma) and abnormalities of lymphatic drainage. Bacterial pneumonia can lead to an accumulation of pleural fluid (parapneumonic effusion). When this fluid is purulent or infected, then it is called an empyema, though often the terms parapneumonic effusion and empyema are used interchangeably. Parapneumonic effusion/empyema is the most common effusion in children. Most parapneumonic effusions are due to pneumonia caused by Streptococcus pneumoniae, group A streptococci, or Staphylococcus aureus.

Clinical Manifestations

Small pleural effusions may be asymptomatic, but if they are large enough to compress lung tissue, then they can cause dyspnea, tachypnea, and occasionally chest pain. Effusions due to infection are usually associated with fever, malaise, poor appetite, pleuritic chest pain, and splinting. Physical findings include tachypnea, dullness to percussion, decreased breath sounds, mediastinal shift (with large effusions), and decreased tactile fremitus.

Diagnostic Studies

The presence of pleural fluid can often be confirmed by chest radiograph. In addition to anteroposterior and lateral projections, a decubitus view should be done to assess for layering of fluid. Chest ultrasonography is useful for confirming the presence of the effusion and quantifying its size. CT scans of the chest can help differentiate pleural fluid from parenchymal lesions and pleural masses. Both ultrasonography and CT scans can determine whether parapneumonic effusions contain loculations (fibrous strands that compartmentalize the effusion).

The analysis of pleural fluid is useful in differentiating a transudate (low pleural fluid to serum lactate dehydrogenase and protein ratios) from an exudate. It is also useful in diagnosing chylous, tuberculous, and malignant effusions. However, the yield of pleural fluid cultures is low. Transudative pleural effusions have a low specific gravity (<1.015) and protein content (<2.5 g/dL), low lactate dehydrogenase activity (<200 IU/L), and a low WBC count with few polymorphonuclear cells. In contrast, exudates are characterized by high specific gravity and high protein (>3 g/dL) and lactate dehydrogenase (>250 IU/L) levels. They may also have a low pH (<7.2); low glucose level (<40 mg/dL); and a high white blood cell count with many lymphocytes or polymorphonuclear leukocytes.

Treatment

Therapy is directed at the underlying condition causing the effusion and at relief of the mechanical consequences of the fluid collection. For small effusions, especially if they are transudates, no pleural drainage is required. Large effusions that are causing respiratory compromise should be drained. Transudates and most exudates other than parapneumonic effusions can be drained with a chest tube. With parapneumonic effusions/empyema, a chest tube alone is often not sufficient because the fluid may be thick and loculated. In such cases, pleural drainage is best achieved with either the administration of fibrinolytic agents via chest tubes or video-assisted thoracoscopic surgery (VATS). Both fibrinolytic therapy via chest tubes and VATS can reduce morbidity and length of hospital stay, but many patients with small to moderate-sized parapneumonic effusions can be managed conservatively with intravenous antibiotics alone.