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Pneumothorax
Classification and external resources
Right sided spontaneous pneumothorax. An arrow indicating the edge of the collapsed lung.
ICD-10	J93., P25.1, S27.0
ICD-9	512, 860
DiseasesDB	10195
MedlinePlus	000087
eMedicine	emerg/469 emerg/470
MeSH	D011030

Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people with chronic lung conditions and those with no other health problems, but many pneumothoraces occur after physical trauma to the chest, blast injury, or as a complication of medical treatment. In the past, creating a pneumothorax was used as a treatment for various lung disorders, such as tuberculosis; this has now been abandoned.

The symptoms of a pneumothorax are determined by the size of the air leak and the speed by which it occurs; they may include chest pain in most cases and shortness of breath in many. The diagnosis can be made by physical examination in severe cases but usually requires a chest X-ray in milder forms. In a small proportion, the pneumothorax compresses the heart and large blood vessels in the chest, leading to fainting and rarely cardiac arrest; this situation is termed tension pneumothorax.

Small pneumothoraces typically resolve by themselves and require no treatment. In larger pneumothoraces or when there are severe symptoms, the air may be aspirated with a syringe, or a one-way chest tube is inserted to allow the air to escape. Occasionally, surgical measures are required, especially if tube drainage is unsuccessful or someone has repeated episodes.

[edit] Definition

A pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. A tension pneumothorax is a life-threatening condition that results from a progressive deterioration and worsening of a simple pneumothorax, associated with the formation of a one-way valve^[1][2]) at the point of a rupture in the lung.^[3]

[edit] Signs and symptoms

Pneumothorax presents mainly as a sudden shortness of breath, dry coughs, cyanosis (turning blue) and pain felt in the chest, back and/or arms. In penetrating chest wounds, the sound of air flowing through the puncture hole may indicate an open pneumothorax, hence the term "sucking" chest wound. The flopping sound of a punctured lung is also occasionally heard. Subcutaneous emphysema is another symptom.

If untreated, hypoxia may lead to hypercapnia, respiratory acidosis, and loss of consciousness. In a tension pneumothorax, shifting of the mediastinum away from the site of the injury can obstruct the superior and inferior vena cava resulting in reduced venous return. This in turn decreases cardiac preload and cardiac output.

Spontaneous pneumothorax has been reported in young people with a marfanoid habitus. The reason for this association, while unknown, is hypothesized to be the presence of subtle abnormalities in connective tissue, though not necessarily in elastin per se. Most spontaneous pneumothorax result from "blebs", expanded alveoli just under the superficial surface of the lung, that rupture allowing the escape of air into the pleural cavity.

• Decreased or absent breath sounds on the affected side
• Tracheal deviation towards unaffected side^[3] (late sign)
• Hyperresonance on percussion^[3]
• Unequal chest rise^[3]
• Shortness of breath
• Rapid breathing^[3]
• Rapid heart rate^[3]
• Low blood pressure^[3]
• Hypoxia (deficiency in the amount of oxygen reaching the tissues)^[3]
• Pale, cool, clammy skin
• Subcutaneous emphysema (air trapped beneath the skin)
• Bluish skin
• Jugular venous distension (enlarged jugular veins; late sign)

[edit] Cause

CT scan of the chest showing a pneumothorax on the patient's left side (right side on the image). A chest tube is in place (small black mark on the right side of the image), the air-filled pleural cavity (black) and ribs (white) can be seen. The heart can be seen in the center.

Pneumothorax can also occur as part of medical procedures, such as the insertion of a central venous catheter into the subclavian vein. Other causes include mechanical ventilation, endotracheal intubation, laparoscopic surgery, emphysema and less commonly other lung diseases bacterial or viral (pneumonia), metastatic tumors especially sarcomas, lymphangioleiomyomatosis, eosinophilic granuloma, cystic fibrosis, alpha1-antitrypsin deficiency, spontaneous or traumatic esophageal rupture, Pneumocystis carinii pneumonia, lung abscess, and asthma^[4].

It most commonly arises:

• Spontaneously (more commonly in tall slim young males and in Marfan syndrome)
• Following a penetrating chest wound
• Following barotrauma to the lungs^[5][6]

It may also be due to:

• Chronic lung pathologies including emphysema, asthma
• Acute infections
• Chronic infections, such as tuberculosis
• Lung damage caused by cystic fibrosis
• Lung Cancer
• Rare diseases that are unique to women such as Catamenial pneumothorax (due to endometriosis in the chest cavity) and lymphangioleiomyomatosis (LAM).

Pneumothoraces are divided into tension and non-tension pneumathoraces. A tension pneumothorax is a medical emergency as air accumulates in the pleural space with each breath. The increase in intrathoracic pressure results in massive shifts of the mediastinum away from the affected lung compressing intrathoracic vessels. A non-tension pneumothorax by contrast is of lesser concern because there is no ongoing accumulation of air and hence no increasing pressure on the organs within the chest.

The accumulation of blood in the thoracic cavity (hemothorax) exacerbates the problem, creating a hemopneumothorax.

[edit] Spontaneous pneumothorax

Spontaneous Pneumothorax can be classified as primary spontaneous pneumothorax and secondary spontaneous pneumothorax. 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).

Primary

A primary spontaneous pneumothorax may occur without either trauma to the chest or any kind of blast injury. This type of pneumothorax is caused when a bleb (an imperfection in the lining of the lung) bursts causing the lung to deflate. The lung is reinflated by the surgical insertion of a chest tube. A minority of patients will suffer a second instance. In this case, thoracic surgeons often recommend thorascopic pleurodesis to improve the contact between the lung and the pleura. If multiple and/or bilateral occurrences continue, surgeons may opt for a far more invasive bullectomy and pleurectomy to permanently adhere the lung to the interior of the rib cage with scar tissue, making collapse of that lung physically impossible. Primary spontaneous pneumothorax is most common in tall, thin men between 17 and 40 years of age, without any history of lung disease. Though less common, it also occurs in women, usually of the same age and body type. The tendency for primary spontaneous pneumothorax sufferers to be tall and thin is not due to weight, diet or lifestyle, but because the genetic predisposition toward those traits often coincides with a genetic predisposition toward high volume lungs with large, burstable blebs. A small portion of primary spontaneous pneumothoraxes occur in persons outside the typical range of age and body type.

Secondary

In secondary spontaneous pneumothorax, a known lung disease is the cause of the collapse^[7]. The most common cause is chronic obstructive pulmonary disease (COPD) with emphysematous bullae. However, there are several other diseases that may also lead to spontaneous pneumothorax:

• Tuberculosis
• Pneumonia
• Asthma
• Cystic fibrosis
• Lung cancer
• Interstitial lung disease
• Marfan syndrome
• Lymphangioleiomyomatosis (LAM)^[8]

[edit] Differential diagnosis

When presented with this clinical picture, other possible causes include:

• Acute Myocardial Infarction: presents with shortness of breath and chest pain, though MI chest pain is characteristically crushing, central and radiating to the jaw, left arm or stomach. Whilst not a lung condition, patients having an MI often happen to also have lung disease.
• Emphysema: here, delicate functional lung tissue is lost and replaced with air spaces, giving shortness of breath, and decreased air entry and increased resonance on examination. However, it is usually a chronic condition, and signs are diffuse (not localised as in pneumothorax).

Careful history taking and examination and a chest X-ray will allow accurate diagnosis.

[edit] Pathophysiology

Mechanics of a sucking chest wound. A. Air enters the chest through the opening in the chest wall during inspiration (a). The lung collapses on the affected side (b), air passes out of affected bronchus. Air enters the bronchus from the collapsed lung (c) and passes to the intact lung. The mediastinum shifts toward the uninvolved side (d), and hemothorax occurs (e). B. During expiration, air escapes through the wound (a). The collapsed lung expands (b). Air passes from the uninvolved side to the lung on involved side and out the trachea (c). The mediastinum shifts to the involved side (d), and hemothorax occurs (e).

The lungs are located inside the chest cavity, which is a hollow space. Air is drawn into the lungs by the diaphragm (a powerful abdominal muscle). The pleural cavity is the region between the chest wall and the lungs. If air enters the pleural cavity, either from the outside (open pneumothorax) or from the lung (closed pneumothorax), the lung collapses and it becomes mechanically impossible for the injured person to breathe, even with an open airway. If a piece of tissue forms a one-way valve that allows air to enter the pleural cavity from the lung but not to escape, overpressure can build up with every breath; this is known as tension pneumothorax. This condition over time results in a gradual accumulation of air to the degree that it begins to put pressure on the mediastinum, compressing the heart and decreasing cardiac output due to the reduced amount of diastolic filling of the ventricles, and also putting pressure against the trachea, causing it to move away from the midline (the center). Because of the increased thoracic pressure, venous return to the heart is decreased, causing a backup of blood into the venous system, as evidenced by distended jugular veins.^[3]

[edit] Diagnosis

The absence of audible breath sounds through a stethoscope can indicate that the lung is not filling the chest cavity. This accompanied by hyperresonance (higher pitched sounds than normal) to percussion of the chest wall is suggestive of the diagnosis. The "coin test" may be positive. Two coins when tapped on the affected side, produce a tinkling resonant sound which is audible on auscultation.^[9]

If the signs and symptoms are doubtful, an X-ray of the chest can be performed, but in severe hypoxia, or evidence of tension pneumothorax emergency treatment has to be administered first. An x-ray can illustrate the collapse of the lung as extra black space, indicating the presence of air, will be seen in the x-ray around the lung. The lung shrivels up away from the affected side and the mediastinum (trachea and other components) will shift towards the unaffected side.^[10]

In a supine chest X-ray the deep sulcus sign is diagnostic^[11], which is characterized by a low lateral costophrenic angle on the affected side.^[12] In layperson's terms, the place where rib and diaphragm meet appears lower on an X-ray with a deep sulcus sign and suggests the diagnosis of pneumothorax.

In Neonates the use of a transilluminator to suspected area will help visualize the air as radiating rings from light source out.

More recently, ultrasound has been shown to be more sensitive than anteroposterior x-ray for detection of pneumothorax. This is important in the initial evaluation of these patients, when the posteroanterior and lateral x-ray studies may not be obtainable due to the patient's clinical condition.^[13]

[edit] Differential diagnosis

A tension pneumothorax must be differentiated from pericardial tamponade. A chest x-ray will distinguish the two, but therapy should never be delayed for x-ray confirmation.^[14] On physical exam, the differentiating factors are listed in the table at right. The sign that occurs in pericardial tamponade in which the pulse is affected by breathing is called pulsus paradoxus, or simply paradoxical pulse.

[edit] Management

The treatment of a pneumothroax depends on its size and the signs and symptoms it is causing. Management may vary from watching and waiting for it to resolve on it own to needle decompression and the placement of a chest tube. In certain situations surgery may be performed. An untreated pneumothorax is an absolute contraindication of transportation by flight.

[edit] Conservative

Small pneumothoraces are often managed conservatively as they will resolve on their own.^[15] Simple observation is sufficient for asymptomatic patients with a minimal pneumothorax, that is, less than 15-20% of normal lung volume or 2–3 cm from apex to cupola.^[16] Close follow-up with repeat observations via chest X-rays is indicated to exclude any expansion, and oxygen is administered.^[17]

[edit] Needle decompression

If the air in the pleural cavity is due to a tear in the lung tissue (in the case of a blast injury or tension pneumothorax), it needs to be released. A thin needle can be used for this purpose, to relieve the pressure and allow the lung to reinflate. Many paramedics can perform needle thoracocentesis to relieve intrathoracic pressure. Pneumothoraces which are too small to require tube thoracostomy and too large to leave untreated, may be aspirated with a small catheter.

[edit] Chest tube

Large pneumothoraces may require tube thoracostomy, also known as chest tube placement. If a thorough anesthetizing of the parietal pleura and the intercostal muscles is performed, the only major pain experienced should be either the injury that caused the pneumothorax or the re-expanding of the lung. Once the chest tube is placed air is extracted using a simple one way valve or vacuum and a water valve device. This allows the lung to re-expand within the chest cavity. The pneumothorax is followed up with repeated X-rays. If the pneumothorax has resolved and there is no further air leak, the chest tube is removed. If, during the time that the tube is still in the chest, the lung manages to sustain the re-expansion, but once suction is turned off, the lung collapses, a Heimlich valve may be used.

[edit] Surgery

In the situation that the chest tube is not sufficient in healing of the lung (for example, a continued air leak despite chest tube drainage), or if CT scans show the presence of large "bullae" on the surface of the lung, thoracoscopic surgery, or video assisted thorascopic surgery (VATS), may be done in order to staple the leak shut and to irritate the pleura to promote adhesions between the lung and pleura (pleurodesis). Two or three small incisions are made in the side of the chest and back, one for a small camera and the other (s) for tools used to seal the lung and abrade or remove the pleura. When finished the wound is covered with a steri-strip and bandaged up.

Recurrent pneumothorax may require further corrective and/or preventive measures such as pleurodesis. If the pneumothorax is the result of ruptured bullae, then bullectomy (the removal or stapling of bullae or other faults in the lung) is preferred. Chemical pleurodesis is the injection of a chemical irritant that triggers an inflammatory reaction, leading to adhesion of the visceral pleura, which is in contact with the lung, to the parietal pleura. Substances used for pleurodesis include talc, blood, tetracycline and bleomycin. Mechanical pleurodesis is done by abrading the pleura and does not use chemicals. The surgeon "roughens" up the inside chest wall ("parietal pleura") so the lung attaches to the wall with scar tissue. This can also include a partial "parietal" pleurectomy, which is the removal of the "parietal" pleura; "parietal" pleura is the serous membrane lining the inner surface of the thoracic cage and facing the "visceral" pleura, which lies all over the lung surface. Both operations can be performed using keyhole surgery (VATS) to minimise discomfort to the patient. Sometimes pneumothorax occurs bilaterally in sequence or, more rarely, simultaneously; that is often associated to bilateral apical blebs and obviously requires bilateral treatment.^[18][19]

[edit] Tension pneumothorax

Tension pneumothorax represents a medical emergency in which the decision to proceed with needle decompression must be made clinically by observing the acute presentation and reviewing relevant history. Once the needle is placed, a chest tube is inserted. Stripping the tubes can cause a negative pressure in the chest tube system. Another option is to create a sterile field, open the chest tube and the connection to the drainage tubing, and introduce a external suction catheter to try to suck out the clogged chest tube. This has the disadvantge of breaking the sterile field, and air can be sucked back into the chest. If the chest tube clogging cannot be cleared, the tube has to be replaced.^{[20][21][22][23]}. Medic kits are available with a small 14 gauge needle and catheter contained within a pen-sized container.^[24]

[edit] Chest wound

Penetrating wounds (also known as 'sucking chest wounds') require immediate coverage with an occlusive dressing, field dressing, or pressure bandage made air-tight with petroleum jelly or clean plastic sheeting. The sterile inside of a plastic bandage packaging is good for this purpose; however in an emergency situation any airtight material, even the cellophane of a cigarette pack, can be used. A small opening, known as a flutter valve, may be left open so the air can escape while the lung reinflates. Any patient with a penetrating chest wound must be closely watched at all times and may develop a tension pneumothorax or other immediately life-threatening respiratory emergency at any moment. They cannot be left alone. In case of penetrating wounds, these require attention, but generally only after the airway has been secured and a chest drain inserted. Supportive therapy may include mechanical ventilation.

[edit] History

Jean Marc Gaspard Itard, a student of René Laennec, first recognised pneumothorax in 1803, and Laennec himself described the full clinical picture in 1819.^[25]

Prior to the advent of anti-tuberculous medications, iatrogenic pneumothoraces were intentionally given to tuberculosis patients in an effort to collapse a lobe, or entire lung around a cavitating lesion. This was known as "resting the lung". It was introduced by the Italian surgeon Carlo Forlanini in 1894 and publicized by the American surgeon John Benjamin Murphy in the early 20th century.^{[citation needed]}

[edit] Image gallery

Chest X-ray of left-sided tension pneumothorax. Note the shift of the mediastinum away from the side with the pneumothorax.

A pneumothorax after placement of a pig tail drain in the second intercostal space mid clavicular line. Arrow indicated the pig tail drain.

[edit] See also

• Pleural effusion
• Hydrothorax
• Pulmonary contusion
• Traumatic aortic rupture
• Pneumohemothorax

[edit] References

[edit] External links

• eMedicine: Pneumothorax
• Pneumothorax Ultrasound Exam Tutorial

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Pneumothorax".