Pneumothorax overview

# Overview
Pneumothorax is air in the pleural space under pressure resulting in lung collapse. Pneumothorax can be classified into tension and non-tension pneumothorax. A tension pneumothorax is an acute medical emergency as air accumulates rapidly in the pleural space with each breath. The increase in intrathoracic pressure results in massive shifting of the mediastinum away from the affected lung compressing intrathoracic vessels. Non-tension pneumothorax is of lesser severity because there is slower accumulation of air and therefore slower increase in air pressure in the pleural cavity. In primary spontaneous pneumothorax, it is usually characterized by a rupture of a bleb in the lung while secondary spontaneous pneumothorax mostly occurs due to chronic obstructive pulmonary disease (COPD). There are several diseases that may lead to secondary spontaneous pneumothorax including tuberculosis, pneumonia, asthma, cystic fibrosis, lung cancer, interstitial lung disease, and Marfan's syndrome. In tension pneumothorax, the underlying pathophysiology most commonly is chest trauma forming a one-way valve in the pleura whereby air enters the pleural space when the pleural pressure is negative during inspiration. Pneumothorax can also result from several interventional procedures which cause penetrating or non-penetrating injury to the pleura resulting in abrupt increase in the alveolar pressure and hence, lead to alveolar rupture forming a communication with the pleura. The prognosis varies with the cause of pneumothorax; primary spontaneous pneumothorax have the most favorable prognosis. The symptoms of pneumothorax usually develop in any decade of life, and start with symptoms such as difficulty breathing, shortness of breath, and chest pain. Uncomplicated pneumothorax usually resolve within 10 days. Secondary pneumothorax is dependent on the underlying cause and can continue to reoccur. If tension pneumothorax is not recognized it will lead to death. Common complications of pneumothorax include recurrence, cardiovascular collapse, and pneumomediastinum. Chest CT scan is more sensitive than chest x-ray and may be helpful in the diagnosis of pneumothorax. Findings on CT scan suggestive of pneumothorax include small pneumothoraces, pneumomediastinum, and blebs. Surgery is the mainstay of treatment for the management of pneumothorax. The type of surgical modality opted depends on various conditions such as the size of the pneumothorax, underlying disease or procedure causing it and the type (open/closed vs simple/tension). Initially, airway, breathing, and circulation should be maintained along with high concentration oxygen therapy. Tube thoracotomy used to be the preferred surgical procedure. Nowadays, video assisted thoracoscopic surgery has widely replaced the open surgical procedure.

# Historical Perspective
Pneumothorax was first discovered by Hippocrates, about 2400 years ago who used a metal drain for treatment. In 1803, French physician Itard was the first to coin the term "pneumothorax." By 1952, synthetic, more flexible drains replaced metal tubes. By 1980s, flexible and plastic drains were used that ranged between 6 and 40 French (F) in size.

# Classification
Pneumothorax can be classified into tension and non-tension pneumothorax. A tension pneumothorax is an acute medical emergency as air accumulates rapidly in the pleural space with each breath. The increase in intrathoracic pressure results in massive shifting of the mediastinum away from the affected lung compressing intrathoracic vessels. Non-tension pneumothorax is of lesser severity because there is slower accumulation of air and therefore slower increase in air pressure in the pleural cavity. In primary spontaneous pneumothorax, it is usually characterized by a rupture of a bleb in the lung while secondary spontaneous pneumothorax mostly occurs due to chronic obstructive pulmonary disease (COPD). There are several diseases that may lead to secondary spontaneous pneumothorax including tuberculosis, pneumonia, asthma, cystic fibrosis, lung cancer, interstitial lung disease, and Marfan's syndrome.

# Pathophysiology
Pneumothorax is air in the pleural space under pressure resulting in lung collapse.The pathophysiology of each type depends on the underlying disease/etiology. Primary spontaneous pneumothorax most commonly results from the bleb (small air-filled lesions under pleural surface) rupture allowing the air to leak into the pleural space. A subclass of primary spontaneous pneumothorax is isolated familial primary spontaneous pneumothorax which is genetically associated with folliculin gene mutation. Secondary spontaneous pneumothorax occurs subsequent to underlying lung pathology such as obstructive lung disease, cystic fibrosis, diffuse parenchymal lung disease and lung cancer. In tension pneumothorax, the underlying pathophysiology most commonly is chest trauma forming a one-way valve in the pleura whereby air enters the pleural space when the pleural pressure is negative during inspiration. Pneumothorax can also result from several interventional procedures which cause penetrating or non-penetrating injury to the pleura resutling in abrupt increase in the alveolar pressure and hence, lead to alveolar rupture forming a communication with the pleura.

# Causes
Pneumothorax can occur as part of medical procedures, such as the insertion of a central venous catheter in the subclavian vein or jugular vein. While rare, it is considered a serious complication and needs immediate treatment. Other causes include mechanical ventilation, emphysema, and rarely other lung diseases such as pneumonia.

# Differentiating pneumothorax from Other Diseases

# Epidemiology and Demographics
The incidence of primary spontaneous pneumothorax is approximately 7.4-18 per 100,000 individuals in males and approximately 1.2-6.0 per 100,000 individuals in females in USA. Patients of all age groups may develop pneumothorax. There is no racial predilection to pneumothorax. Males are more commonly affected by pneumothorax than females. The male to female ratio is approximately 3 to 1.

# Risk Factors
Common risk factors in the development of pneumothorax include smoking, underlying lung pathology such as obstructive lung diseases, female gender, thin and tall men, mechanical ventilation, low body weight, Marfan's syndrome, and homocystinuria.

# Screening
There is insufficient evidence to recommend routine screening for pneumothorax.

# Natural History, Complications, and Prognosis
The prognosis varies with the cause of pneumothorax; primary spontaneous pneumothorax have the most favorable prognosis. The symptoms of pneumothorax usually develop in any decade of life, and start with symptoms such as difficulty breathing, shortness of breath, and chest pain. Uncomplicated pneumothorax usually resolve within 10 days. Secondary pneumothorax is dependant on the underlying cause and can continue to reoccur. If tension pneumothorax is not recognized it will lead to death. Common complications of pneumothorax include recurrence, cardiovascular collapse, and pneumomediastinum.

# Diagnosis

## Diagnostic Criteria
History and physical exam is the diagnostic test of choice for pneumothorax. A CT scan can is the most sensitive test for pneumothorax. Tension pneumothorax is a medical emergency and should be treated promptly after the physical exam.

## History and Symptoms
The most common symptoms of pneumothorax include sharp chest pain, difficulty breathing, anxiety, and increased work of breathing. Less common symptoms of pneumothorax include hypotension, cyanosis, and decreased level of consciousness.

## Physical Examination
Patients with primary spontaneous pneumothorax usually appear normal. Physical examination of patients with primary spontaneous pneumothorax is usually remarkable normal. Patients with secondary spontaneous pneumothorax usually appear in distress. Physical examination of patients with secondary spontaneous pneumothorax is usually remarkable for dyspnea, chest pain, and neck vein distension. Patients with tension pneumothorax usually appear dyspnic and distressed. Physical examination of patients with tension pneumothorax is usually remarkable for tracheal deviation, decreased chest expansion, increased percussion note, decreased breath sounds, and neck veins distension.

## Laboratory Findings
There are no diagnostic laboratory findings associated with pneumothorax.

## Electrocardiogram
Left-sided pneumothorax ECG will show rightward shift of the frontal QRS axis, decreased precordial R voltage, decrease in QRS amplitude, and precordial T-wave inversion. Right sided pneumothorax ECG may show decreased precordial QRS voltage, right axis deviation, and prominent R wave in V2 with loss of S wave voltage.

## X-ray
A chest x-ray may be helpful in the diagnosis of pneumothorax. Findings on an x-ray suggestive of pneumothorax include absent lung markings, white pleural lines, mediastinal shift to the opposite side, atelectasis, air fluid levels in pleural space, and deep sulcus sign. X-ray challenges for pneumothorax include air trapped between chest wall and arm will be seen as a lucency rather than a visceral pleural white line, scapula edge should be followed to make sure it does not project over chest, skin fold appear thicker than the thin visceral pleural white line, and emphysematous bullae cane be seen as convexity laterally.

## Ultrasound
There are no echocardiography findings associated with pneumothorax. Ultrasonography will show absence of lung sliding, absence of comet-tail artifact, and presence of lung point. Pneumothorax detection is part of the FAST examination in trauma centers.

## CT scan
Chest CT scan is more sensitive than chest x-ray and may be helpful in the diagnosis of pneumothorax. Findings on CT scan suggestive of pneumothorax include small pneumothoraces, pneumomediastinum, and blebs.

## MRI
There are no MRI findings associated with pneumothorax.

## Other Imaging Findings
There are no other imaging findings associated with pneumothorax.

## Other Diagnostic Studies
There are no other diagnostic studies associated with pneumothorax.

# Treatment

## Medical Therapy
There is no medical management of pneumothorax.

## Surgery
Surgery is the mainstay of treatment for the management of pneumothorax. The type of surgical modality opted depends on various conditions such as the size of the pneumothorax, underlying disease or procedure causing it and the type (open/closed vs simple/tension). Initially, airway, breathing, and circulation should be maintained along with high concentration oxygen therapy. Tube thoracotomy used to be the preferred surgical procedure. Nowadays, video assisted thoracoscopic surgery has widely replaced the open surgical procedure.

## Primary Prevention
Effective measures for the primary prevention of pneumothorax include preventive measures during driving such as wearing seat belts and performing invasive procedures involving pleura under ultrasound guidance to prevent pleural damage.

## Secondary Prevention
There are no established measures for the secondary prevention of pneumothorax.