Differentials
Asthma, acute exacerbation
SIGNS / SYMPTOMS
Expiratory wheeze and chest tightness.[47]
INVESTIGATIONS
Therapeutic trial of bronchodilators relieves symptoms.
COPD, acute exacerbation
SIGNS / SYMPTOMS
Fever, increased cough, and change in sputum color suggest an infective exacerbation. Bullous pulmonary disease may, however, be clinically indistinguishable from pneumothorax.[47]
INVESTIGATIONS
Usually, a chest x-ray will suffice but a CT of the chest may be necessary to differentiate a pneumothorax from a pulmonary bulla.[41]
Pulmonary embolism
SIGNS / SYMPTOMS
Presence of risk factors for thromboembolism, such as obesity, prolonged bed rest, pregnancy/postpartum period, inherited thrombophilias, active malignancy, recent trauma/fracture, and history of previous thrombosis. Physical exam abnormalities suggestive of deep venous thrombosis are present in 50% of patients.[2]
INVESTIGATIONS
The chest x-ray is most commonly normal, but pulmonary vascular oligemia and atelectasis may be present. Pulmonary infiltrates may develop and can be of any shape, not just wedge-shaped.
CT pulmonary angiogram with direct visualization of thrombus in a pulmonary artery.
Ventilation-perfusion scan (V/Q scan) with an area of ventilation that is not perfused.
Myocardial ischemia
SIGNS / SYMPTOMS
Typically the patient complains of chest tightness and shortness of breath that is brought on by exertion. The chest discomfort is usually substernal and is described as a pressure sensation. Pain may radiate into the neck and down the arms. Nausea, vomiting, and diaphoresis may accompany the chest discomfort.
INVESTIGATIONS
An ECG may demonstrate ischemia or injury patterns.
Serum levels of cardiac biomarkers increase when myocardial infarction has occurred.
Pleural effusion
SIGNS / SYMPTOMS
Patients will experience pain. However, as fluid accumulates in the pleural space, the visceral and parietal pleura will move apart and chest pain will ease. Physical exam demonstrates decreased fremitus, dullness to percussion, and decreased breath sounds. As pleural fluid accumulates, the patient may experience shortness of breath.
Patients may develop post-drainage pneumothorax ex vacuo in the setting of unexplainable lung (no intervention is generally needed in this case).
INVESTIGATIONS
A chest x-ray is typically diagnostic of a pleural effusion. A meniscus sign at the costophrenic angle in an upright chest radiograph is diagnostic. Between 250 and 500 mL of pleural fluid is necessary to visualize effusion by chest x-ray.
CT scans are more sensitive and may give additional clues to the clinician concerning the etiology of the pleural fluid.
Bronchopleural fistula
SIGNS / SYMPTOMS
A bronchopleural fistula is a communication between the pleural space and the bronchial tree that persists for 24 hours or more. The most common cause of bronchopleural fistulas is postoperative complication of pulmonary resections. Other etiologies include lung necrosis complicating infection, persistent spontaneous pneumothorax, chemotherapy or radiation therapy for bronchogenic carcinoma and metastatic cancer to the lung, and tuberculosis.
The presentation is characterized by sudden appearance of dyspnea, hypotension, subcutaneous emphysema, cough, and purulent sputum, and shifting of the trachea and mediastinum.[48]
INVESTIGATIONS
The diagnosis is established by placing a chest tube or small-bore catheter into a pneumothorax and demonstrating a persistent air leak.
Fibrosing lung disease
SIGNS / SYMPTOMS
Patients typically complain of slowly progressive dyspnea. Crackles are present on auscultation of the chest. A prominent second heart sound may also be evident. The patient may have digital clubbing.
INVESTIGATIONS
A chest x-ray is often the initial radiologic exam when fibrotic lung disease is suspected.
CT scanning, however, is more sensitive and helps in determining whether there is an active inflammatory disease of the lung. A ground-glass infiltrate indicates that alveolitis is present.
Further diagnostic studies and therapeutic interventions may be necessary.
Esophageal perforation
SIGNS / SYMPTOMS
Esophageal perforations most commonly occur after medical instrumentation or paraesophageal surgery, and following sudden increase in intraesophageal pressure combined with negative intrathoracic pressure caused by straining or vomiting (Boerhaave syndrome).
Patients complain of severe retrosternal chest and upper abdominal pain. Odynophagia, tachypnea, dyspnea, cyanosis, fever, and shock develop rapidly thereafter. The physical exam is usually not helpful, particularly early in the course. Subcutaneous emphysema (crepitation) is an important diagnostic finding but is not very sensitive. A pleural effusion with or without a pneumothorax may be present.
INVESTIGATIONS
Plain chest radiography is almost always abnormal in esophageal rupture. Early in the course of the disease, the diagnosis is suggested by mediastinal or free peritoneal air. Later, there is widening of the mediastinum, subcutaneous emphysema, and pleural effusion with or without a pneumothorax. A CT scan may demonstrate esophageal wall edema and thickening, extraesophageal air, periesophageal fluid with or without gas bubbles, mediastinal widening, and air and fluid in the pleural spaces and the retroperitoneum.
The diagnosis can also be confirmed by water-soluble contrast esophagram, which reveals the location and extent of extravasation of contrast material.
Giant bullae
SIGNS / SYMPTOMS
Patient's symptoms and physical exam may mimic those of a pneumothorax. The patient may also present with acute dyspnea due to another cause (e.g., an exacerbation of COPD).
INVESTIGATIONS
A giant bulla is defined as a bulla that occupies one third or more of the ipsilateral hemithorax and develops slowly over time. However, if there are no old x-rays available for comparison, then differentiation from a pneumothorax may be impossible. Faint radiopaque lines within the bulla may be the only clue that the abnormality seen on the chest x-ray is not a pneumothorax.
Because placement of a chest tube into a giant bulla can have deleterious results, a CT scan of the chest should be obtained to help make the differentiation between both diagnoses.
Use of this content is subject to our disclaimer