Pulmonary Medicine

Pneumothorax

What every physician needs to know:

A pneumothorax is present when there is air in the pleural space. Primary spontaneous pneumothoraces are usually more of a nuisance than they are life-threatening, while secondary pneumothoraces can be life-threatening because of limited lung reserve. Tension pneumothorax is a medical emergency that, if not readily diagnosed and treated, is likely to be fatal. Fortunately, tension pneumothoraces rarely occur spontaneously and are generally secondary to positive pressure ventilation.

Classification:

Pneumothoraces are classified as spontaneous pneumothoraces or traumatic pneumothoraces. Spontaneous pneumothoraces are further classified as primary spontaneous pneumothorax, which occurs in patients without obvious underlying lung disease, and secondary spontaneous pneumothorax, which occurs in patients with underlying lung disease. A special type of primary spontaneous pneumothorax is a catamenial pneumothorax, which is a pneumothorax that occurs during the menstrual cycle, the mechanism of which remains debated.

Most primary spontaneous pneumothoraces occur in smokers and are a felt to be secondary to areas of air trapping due to small airway disease. Visceral pleural blebs (“emphysema-like changes”) are almost universally found during surgical management of primary spontaneous pneumothorax but recent data suggest that they may not be directly responsible [Noppen 2006]. Most secondary spontaneous pneumothoraces are secondary to chronic obstructive lung disease (COPD), although other classical causes of secondary spontaneous pneumothorax include tumor, sarcoidosis, tuberculosis, interstitial lung disease, cystic fibrosis, Langerhans cell histiocytosis, lymphangioleiomyomatosis, Birt-Hogg-Dube syndrome and pulmonary infections. Traumatic pneumothoraces are pneumothoraces that occur as a result of direct or indirect trauma to the chest. Many traumatic pneumothoraces are iatrogenic pneumothoraces, which occur as an intended or inadvertent consequence of a diagnostic or therapeutic maneuver.

An occult traumatic pneumothorax is a pneumothorax that is not evident on a chest radiograph but is evident on a CT scan of the chest. A tension pneumothorax is a pneumothorax in which the pleural pressure is positive throughout the respiratory cycle and associated with hemodynamic compromise. It usually occurs in patients who are receiving mechanical ventilation or who are being resuscitated.

Are you sure your patient has a pneumothorax? What should you expect to find?

Symptoms of primary spontaneous pneumothorax are dyspnea and chest pain. Signs of primary spontaneous pneumothorax are decreased or absent breath sounds on the side of the pneumothorax, the absence of tactile fremitus on the side of the pneumothorax, enlarged hemithorax on the side of the pneumothorax, and tachycardia and hypotension if the pneumothorax is large and causing early tension.

Symptoms of secondary spontaneous pneumothorax typically consist of dyspnea, chest pain, hypoxia, and hypercapnic respiratory failure as there is often poor respiratory function prior to the development of the pneumothorax. Signs of secondary spontaneous pneumothorax are decreased or absent breath sounds on the side of the pneumothorax, although these may not be readily apparent because these patients often have decreased breath sounds over both lungs as a result of their COPD; the absence of tactile fremitus on the side of the pneumothorax; cyanosis; and altered mental state if there is hypercapnic respiratory failure.

Symptoms of tension pneumothorax are dyspnea, chest pain, and diaphoresis. Signs of tension pneumothorax are tachycardia (and, later, bradycardia), hypotension, increasing ventilator pressures (peak and plateau pressures) if the patient is on a volume-controlled ventilator setting, decreasing tidal volume if the patient is on a pressure-controlled ventilator, difficulty ventilating the patient during resuscitation, the absence of tactile fremitus on the side of the pneumothorax, decreased or absent breath sounds on the side of the pneumothorax, enlarged hemithorax on the side of the pneumothorax, shift of the trachea to the contralateral side, and subcutaneous emphysema.

Beware: there are other diseases that can mimic a pneumothorax:

Other diseases that can mimic the symptoms of primary spontaneous pneumothorax are pulmonary embolism and pneumonia.

Large bullae in the lungs, exacerbation of COPD, and congestive heart failure can mimic secondary spontaneous pneumothorax.

There are no other diseases that can mimic the symptoms and signs of non-iatrogenic traumatic pneumothorax, as the diagnosis is almost always made with chest radiographs.

Iatrogenic pneumothorax can be mimicked by pulmonary embolism, pneumonia, and congestive heart failure.

Other diseases or conditions that can mimic the symptoms of tension pneumothorax are an obstructed endotracheal or tracheostomy tube, high intrinsic PEEP, and tension pleural effusion.

How and/or why did the patient develop a pneumothorax?

Studies suggest that small airway disease (often caused by cigarette smoke) leads to peripheral area of air-trapping and visceral pleural blebs (“emphysema-like changes”). The visceral pleura in these areas may be abnormally permeable to air (“pleural porosity”) and result in accumulation for air in the pleura space. Alternatively, some cases are likely due to bleb ruptures, since symptoms often start abruptly.

With penetrating trauma, air enters the pleural space through a hole in the chest wall or a hole in the visceral pleura. With non-penetrating trauma, sudden chest compression leads to elevated alveolar pressure, which can result in alveolar rupture (as in barotrauma in divers for instance). Air enters the interstitial space and then moves to the visceral pleura or mediastinum. A subsequent rupture of one of these results in a pneumothorax. With penetrating injuries, “sucking” chest wounds may result in a ball-valve phenomenon which could lead to tension pneumothorax and death. Immediate decompression is warranted.

Iatrogenic pneumothorax occurs after a procedure known to be potentially complicated by pneumothorax. The condition is usually due to a hole in the visceral pleura, such as one made during transthoracic needle aspiration, transbronchial biopsy, or mechanical ventilation. At times, the condition is due to air entering the pleural space from the atmosphere from a faulty technique with thoracentesis or needle biopsy of the pleura.

Almost all patients with tension pneumothorax have positive pressure applied to their airway, most commonly with mechanical ventilation or resuscitation, as positive pressure on the airway is necessary to get positive pressure throughout the respiratory cycle in the pleural space. On rare occasions, tension pneumothorax can develop without positive airway pressure, but one must invoke a one-way valve between the alveoli (or the chest wall) and the pleural space.

Which individuals are at greatest risk of developing a pneumothorax?

Ninety percent of primary spontaneous pneumothorax patients are smokers. Most patients have subpleural blebs, which may be related to smoking and are synonymous with emphysema-like changes (ELC). Patients tend to be taller and thinner than the average individual, and most patients are 20-35 years old. Pneumothorax is six times more common in men than in women. In addition, the tendency to pneumothorax may be inherited (e.g. Birt-Hogg-Dube syndrome).

Secondary spontaneous pneumothorax is most common in patients who have COPD; the worse the COPD, the more likely the patient is to develop a pneumothorax. In addition, most patients have subpleural blebs.

What laboratory studies should you order to help make the diagnosis, and how should you interpret the results?

There are no laboratory tests that help make the diagnosis of pneumothorax.

What imaging studies will be helpful in making or excluding the diagnosis of a pneumothorax?

The upright chest radiograph is most helpful in making or excluding the diagnosis of pneumothorax. A PA chest radiograph is best, as the patient should be upright because air will rise in the hemithorax. Diagnosis of pneumothorax is made when a pleural line is demonstrated that is differentiated from the line of a skin fold. (In a skin fold, the inside gradually changes from white to black, while a pneumothorax changes to black right inside the pleural line). When a pneumothorax is present, there are no lung markings in the peripheral to pleural line, and the markings in the central to pleural line are denser than the peripheral to pleural line. Expiratory films are no more sensitive than inspiratory films.

Supine radiographs are less helpful in making or excluding the diagnosis of pneumothorax. The pneumothorax is missed in 30 percent, and half of these progress to tension pneumothorax. Pneumothoraces occur most commonly in the anteriomedial area, where they are manifested as a deep sulcus sign (an exceptionally deep radiolucent costophrenic sulcus), they are much sharper than the normal appearance of a hemidiaphragm, and there is lucency over the right or left upper quadrant.

Chest ultrasound also crucial in assessing the diagnosis of pneumothorax. It is used more often in diagnosis of traumatic and iatrogenic pneumothorax, as it is easily and rapidly performed at bedside. The presence of a lung sliding sign or B-lines on 2-dimensional mode and seashore sign (M-mode) excludes a pneumothorax. However, their absence is only suggestive of pneumothorax, unless a lung point, marking the separation of visceral and parietal pleura, is present as well. The lung point is not visible with complete a separation of the pleural surfaces, as in large pneumothoraces.

A CT scan of the chest is also helpful in making or excluding the diagnosis of pneumothorax. In fact, it is the most accurate way to diagnose pneumothorax. An occult pneumothorax is evident on a CT scan of the chest, but not on a chest radiograph. Recent data suggest that screening for cystic lung diseases after an initial spontaneous pneumothorax may be reasonable [Gupta 2016].

What non-invasive pulmonary diagnostic studies will be helpful in making or excluding the diagnosis of a pneumothorax?

There are no non-invasive pulmonary diagnostic studies, other than imaging, that are useful in making or excluding the diagnosis of pneumothorax.

What diagnostic procedures will be helpful in making or excluding the diagnosis of a pneumothorax?

Only imaging studies are helpful in making or excluding the diagnosis of pneumothorax

What pathology/cytology/genetic studies will be helpful in making or excluding the diagnosis of a pneumothorax?

When pneumothorax is associated with cystic lung disease, DNA-based diagnosis to assess the folliculin gene on chromosome 17p11.2 is indicated to establish the diagnosis of Birt-Hogg-Dube. Likewise, elevated vascular endothelial growth factor D may suggest lymphangioleiomyomatosis. Elevated levels of cd1A positive cells in the bronchoalveolar lavage of patients with cystic lung disease suggest LCH. Otherwise, there are no other pathology/cytology/genetic studies that are helpful in making or excluding the diagnosis of pneumothorax.

If you decide the patient has a pneumothorax, how should the patient be managed?

Primary spontaneous pneumothorax

Treatment depends on the size of the pneumothorax and the patient's symptoms. If the patient is asymptomatic and the distance between the outside of the lung and the inside of the chest wall at the level of the hilum is less than 2 cm, observation is the recommended treatment. Note that the definition of “large” pneumothorax is highly controversial, and some experts recommend treatment of symptomatic primary spontaneous pneumothoraces only. In the presence of a primary spontaneous pneumothorax, the rate of air reabsorption is about 1.25 percent of the hemithorax per day. The rate of air reabsorption will be several times higher if high levels of supplemental O2 are administered.

If the patient is symptomatic or if the distance between the outside of the lung and the inside of the chest wall is greater than 2.0 cm, the air should be aspirated from the pleural space. A 14 to 16-gauge needle or 5-french catheter can be inserted in the anterior second or third intercostal space, and air is withdrawn until no more air is obtained or a total of 4L of air is withdrawn. Aspiration is successful in about 67 percent of cases. After successful aspiration, an immediate chest X-ray is obtained and the patient is watched for at least 4 hours, after which a chest radiograph is repeated; if there is no recurrent pneumothorax or the pneumothorax is small and stable, the patient may be sent home. An alternative to needle aspiration is to place a small chest tube (8-14 Fr) and send the patient home with a Heimlich valve on the chest tube with close follow-up (within 24 to 48 hours).

If aspiration fails, a small chest tube (8-14Fr) should be placed and the patient admitted to the hospital. If a chest tube is placed, suction is not recommended in the first twenty-four hours because re-expansion pulmonary edema is more likely if suction is applied. If the lung is not expanded after twenty-four hours, then suction may be applied [Massongo 2014].

Complications with primary spontaneous pneumothorax occur when there is a persistent air leak after forty-eight hours, which is an indication for thoracoscopy or autologous blood patch. An unexpanded lung after forty-eight hours is an indication for thoracoscopy.

The recurrence rate is about 50 percent with aspiration or chest tube, about 25 percent if a sclerosing agent like talc, doxycycline, or silver nitrate is instilled through a chest tube, and about 5 percent with thoracoscopy or thoracotomy. Recommendations for prevention of recurrence focus on the use of video-assisted thoracoscopy surgery (VATS). With VATS, the blebs are stapled and attempts are made to create a pleurodesis by pleural abrasion, apical parietal pleurectomy, or instillation of a pleurodesing agent like doxycyline, silver nitrate, or talc.

Patients with the following characteristics should undergo VATS up front:

  • Recurrent ipsilateral pneumothorax

  • Contralateral pneumothorax

  • Synchronous bilateral pneumothorax

  • Persistent air leak or failure of the lung to expand after forty-eight hours

  • Participation in a profession where recurrent pneumothorax would be dangerous (e.g., pilots, divers, mountain climbers)

An alternative to VATS is medical thoracoscopy with the instillation of a sclerosing agent like talc. However, medical thoracoscopy does not treat the blebs. No randomized controlled studies have compared VATS with medical thoracoscopy, though limited evidence suggest that talc pleurodesis via medical thoracoscopy may be effective in the majority of cases [Tschopp 1997].

Secondary spontaneous pneumothorax

Treatment options for secondary spontaneous pneumothorax are the same as those for primary spontaneous pneumothorax. Aspiration is not recommended because it is likely to be unsuccessful. Chest tubes (9-14 fr) are indicated in almost all patients, but chest tubes are less effective than they are in primary spontaneous pneumothorax. Larger bore-chest tubes may occasionally be needed with large air leaks. The mean time for the lung to expand is five days, but in 20 percent, the lung remains unexpanded or air leak persists after seven days. If the lung is not expanded after twenty-four hours, suction should be applied.

Complications with secondary spontaneous pneumothorax include death, hypercapnic respiratory failure, persistent air leak after five days (an indication for thoracoscopy or autologous blood patch), and unexpanded lung after five days (an Indication for thoracoscopy).

Recurrence rates are similar to those with primary spontaneous pneumothorax. Attempts should be made to prevent a recurrence in virtually every patient with secondary spontaneous pneumothorax since a recurrence of the pneumothorax can be life-threatening. Video-assisted thoracoscopy surgery (VATS) is the recommended procedure to prevent recurrence, but a sclerosant can be installed through a chest tube if the patient is not a candidate for or refuses VATS. If a chest tube is placed, suction is not recommended in the first twenty-four hours because re-expansion pulmonary edema is more likely if suction is applied.

Traumatic pneumothorax

Chest tubes indicated for most patients with traumatic pneumothorax. However, 90 percent of small pneumothoraces (<1.5 cm from lung to chest wall) do not get larger, and chest tubes are indicated in these patients only if the pneumothorax enlarges with observation. VATS is indicated if the lung remains un-expanded or an air leak persists after seventy-two hours.

Complications with secondary spontaneous pneumothorax include hemothorax, in which case one chest tube should be placed in the inferior hemithorax and, if bleeding persists, VATS should be performed. Other complications--and other indications for VATS--are persistent air leak after five days and unexpanded lung after five days. Tension pneumothorax is another possible complication.

Occult pneumothorax

For occult pneumothorax, observation is sufficient for most patients, although supplemental oxygen will increase the rate of air absorption. If the patient is going to receive mechanical ventilation, a chest tube should be considered, though recent data suggest that close observation may be a valid approach as well [Plurad 2007].

Iatrogenic pneumothorax

Most iatrogenic pneumothoraces are treated more aggressively than necessary, as nothing needs to be done to prevent a recurrence. Simple observation is indicated if the patient is asymptomatic, but supplemental oxygen will increase the rate of air reabsorption. If the patient is symptomatic, aspiration is indicated, and a small-bore chest tube can be inserted if aspiration is unsuccessful. A large-bore chest tube can be used if the lung does not expand with insertion of a small-bore chest tube.

Tension pneumothorax

The clinician should not waste time obtaining radiologic confirmation of tension pneumothorax. If the condition is suspected, a needle catheter system should be inserted into the second or third intercostal space. Ideally, a stopcock and a syringe with a small amount of saline should be attached to the catheter. Once the catheter is inserted and the needle withdrawn, the plunger is removed from the syringe and the stopcock to the syringe opened. Any bubbling through the saline in the syringe confirms that there is positive pressure in the pleural space and confirms the diagnosis. A proper thoracostomy chest tube should then be placed.

What is the prognosis for patients managed in the recommended ways?

The prognosis for patients with all types of pneumothoraces is good. Although the recurrence rate for both primary and secondary spontaneous pneumothorax is approximately 50 percent if no measures are taken to prevent recurrence, the prognosis is still excellent. Smoking is a known contributor to pneumothorax recurrence as demonstrated by a nearly 20-fold increase in recurrence when compared to non-smokers [Cardillo 2016]. As such, smoking cessation is paramount for optimal management of the individual suffering from pneumothorax.

What other considerations exist for patients with a pneumothorax?

If the patient has the Birt-Hogg-Dube syndrome, genetic counseling should be done to inform the patient that the syndrome is transferred as an autosomal dominant manner. If the patient has the Birt-Hogg-Dube syndrome, a CT scan of the kidneys should be obtained to rule out kidney lesions.

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