Pneumothorax/pneumomediastinum

OVERVIEW: What every practitioner needs to know

Are you sure your patient has a pneumothorax? What are the typical findings for this disease?

A pneumothorax is a collection of air that accumulates in the pleural space. A primary spontaneous pneumothorax occurs in individuals without lung disease while a secondary spontaneous pneumothorax occurs as a consequence of pre-existing pulmonary disease. These two types of pneumothoraces are the focus of this review. In addition, there may be traumatic pneumothoraces, which occur due to injury to the chest wall injury or iatrogenic pneumothoraces, which most commonly occur as a complication of central venous catheter placement on mechanical ventilation.

The most common presentation of a primary spontaneous pneumothorax is the sudden onset of a sharp chest pain accompanied by shortness of breath in a patient without a known history of lung disease. Other symptoms may include ipsilateral shoulder pain or dry cough. The symptoms may start at rest, with minimal exertion or in association with coughing or activity.

A collection of air in the mediastinum is called a pneumomediastinum. Spontaneous pneumomediastinum is rare in pediatrics and is most commonly associated with asthma. The classic presentation is that of the sudden onset of pleuritic chest pain (usually retrosternal) with dyspnea and subcutaneous emphysema. However, this triad is only present in about 40% of cases. The pain may radiate to the neck or arms. It may also be accompanied by dysphagia or dysphonia. Hamman’s sign (precordial systolic crepiations, sometimes associated with decreased heart sounds) may also be present. A traumatic pneumomediastinum may occur as the result of chest wall trauma, mechanical ventilation or esophageal perforation.

Physical findings:

Findings may include tachypnea, tachycardia, diminished breath sounds and hyperresonant percussion on the affected side. With a tension pneumothorax, there may also be respiratory distress, cyanosis, hypotension, a shift of the trachea to the contralateral side and hypoxemia.

What other disease/condition shares some of these symptoms?

The differential diagnosis of pneumothorax includes other causes of pleuritic pain. Precordial catch syndrome (Texidor’s twinge) results in brief episodes of sudden, sharp, localized chest pain. The pain is worse with inspiration and usually lasts only a few seconds. Gastroesophageal reflux can result in chest pain but it is not usually localized to one side and is not usually associated with shortness of breath. Pneumonia or respiratory infection may be associated with chest pain. Cardiac causes of chest pain are unusual in pediatrics but should be considered if chest x-ray does not confirm the diagnosis of pneumothorax.

Underlying conditions associated with pneumothoraces include asthma, cystic fibrosis, interstitial lung disease, respiratory infection, connective tissue diseases and congenital anomalies of the lung. Pneumothorax may sometimes be the initial presentation of these disorders. Thoracic endometriosis is a rare cause of pneumothoraces in women. Malignancy, though associated with pneumothoraces in adults, is a rare cause in pediatrics.

The differential diagnosis of pneumomediastinum includes pericarditis and esophageal perforation. An electrocardiogram may show diffuse microvoltage, depressed ST interval, T-wave inversion or rotation of the axis of the heart. In the setting of chest pain, reduced heart sounds and an abnormal ECG, echocardiaogram may be indicated to rule out pericarditis. The other key disorder to rule out is esophageal perforation (Boerhaave’s syndrome) which may occur after severe vomiting or esophageal foreign body.

What caused this disease to develop at this time?

A spontaneous pneumothorax occurs when there is sufficiently increased intra-alveolar pressure to cause alveolar rupture. Often this occurs in the setting of unrecognized apical blebs. Alveolar rupture may occur with Valsalva maneuver associated with straining or heavy lifting. It may also occur as a consequence of small airways obstruction due to mucus, inflammation or mechanical obstruction. In addition, it may occur in association with changes in barometric pressure such as occur at high altitude or with diving.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

The diagnosis of the pneumothorax is made with radiographic studies.

Would imaging studies be helpful? If so, which ones?

The initial radiographic study to evaluate for any pneumothorax should be an erect posterior and anterior (PA) chest x-ray (CXR). The presence of air between the visceral and parietal pleura is noted as an area of lucency at the apex or along the lateral chest wall seen on the affected side. A thin (less than 1 mm) line is visible at the edge of the visceral pleura. In addition, the affected hemithorax may appear more lucent with prominence of the lung and vascular markings.

In cases where the diagnosis is in question, lateral, lateral decubitus or expiratory films may be helpful in detecting small pneumothoraces. However, these studies are not routinely indicated for the diagnosis of a pneumothorax. A lateral chest x-ray may be helpful in looking for causes of secondary pneumothorax in patients with underlying lung disease (See Figure 1).

In adults, the size of the pneumothorax can be estimated on chest x-ray. Pneumothorax is considered to be large if the space between the chest wall and lung is more than 3 cm at the apex or 2 cm at the lateral margin. This corresponds to a 20-30% pneumothorax. There is no agreed upon method for estimating the size of the pediatric pneumothorax.

A computed tomography (CT) scan of the chest should not be needed to diagnose a pneumothorax. It may be indicated to evaluate for underlying lung disease or to look for the presence of blebs or bullae in patients with recurrent pneumothoraces (See Figure 2).

Chest x-ray is the gold standard for the diagnosis of a pneumomediastinum. The frontal and lateral views are both helpful. Findings include gas outlining the mediastinal structures including the heart, aorta and diaphragm. On the frontal view there may be a vertical stripe along the left heart border and aortic arch with air between the pericardium in the diaphragm. In infants, there may be displacement of the thymus upward and outward (spinnaker sign). The lateral view may show retrosternal, precardiac, periaortic or peritracheal air. There may also be subcutaneous emphysema in the neck, upper extremities, chest wall, peritoneal cavity or retroperitoneum (See Figure 3 and Figure 4).

As with pneumothorax, CT scan is useful if underlying lung disease is suspected.

Confirming the diagnosis

There are no algorithms derived from strong evidence based guidelines. The recommendations contained here are similar to those for adults published in guidelines from the British Thoracic Society in the American College of Chest Physicians.

There is an algorithm for managing pneumomediastinum in children over 6 years of age available in the excellent review on this topic by Chalumeau (Pediatric Pulmonology). This is based primarily on expert opinion.

If you are able to confirm that the patient has a pneumothorax, what treatment should be initiated?

The first priority is to assure that the patient is stable. While the evaluation in progress, patient should be placed on supplemental oxygen, pulse oximetry and cardiorespiratory monitor. For any patient who is not clinically stable, prompt evacuation of accumulated air by needle aspiration or chest placement is required. Subsequent treatment is dependent upon whether the pneumothorax is primary or secondary, whether it is the initial occurrence or recurrence and the size of the air accumulation.

Small (<15-20% of the hemithorax) primary pneumothorax with the first occurrence: These patients can be admitted to the hospital and treated conservatively. Administration of 100% oxygen at high flow rates increases resorption of air from the pleural space by creating a partial pressure gradient of nitrogen between the pleural space and capillaries. In addition, other supportive measures and analgesia should be provided. A followup chest x-ray should be obtained at 12 hours in teens and 24 hours in younger patients. If the pneumothorax is improved, the patient can be discharged home with close outpatient followup. This may be successful in 50-80% of patients. Patient who have an increase in the size of the pneumothorax will need placement of a catheter for evacuation of the air.

Medium to large (>15-20%) primary pneumothorax with the first occurrence: In a stable patient, needle aspiration can be attempted using a large-bore Angiocath, a stopcock and a large syringe. In adults this has been reported to be successful in up to 70% of patients with a moderate-sized pneumothorax. The patient should be admitted and observed for 24 hours without reaccumulation of air before discharge home. Aspiration of more than 2.5 L in an adult size person is indicative of an ongoing air leak. If continuous aspiration of air is required, the angiocath can be taped in place and attached to a Heimlich one-way valve. However, insertion of a chest tube or a pigtail catheter is usually required. Chest tube drainage has been reported to be successful in 90% of adults with the first pneumothorax.

Persistent primary pneumothorax: When the pneumothorax persists beyond 4-7 days, surgical intervention may be considered. However, this is not a consensus opinion. Other authors recommend treatment with chest tube drainage for 2 weeks before intervention. One adult series has demonstrated resolution of 75% of primary spontaneous pneumothorax after 7 days of chest tube drainage. This increased to 100% by 15 days.

Primary pneumothorax, recurrent: Surgical intervention should be considered for patients with a recurrent pneumothorax. Recommendations vary as to whether this is indicated with the first or second recurrence. Some authors have demonstrated recurrence risk as high as 50-61% in pediatric patients. Some also recommend surgical management for the first contralateral pneumothorax.

Secondary spontaneous pneumothorax:Patients with cystic fibrosis or asthma and small pneumothoraces may be treated with oxygen therapy and close observation if they are clinically stable. Those with a large pneumothorax will require chest tube placement. While patients with cystic fibrosis are at high risk for recurrence (50-90%), the consensus opinion of the Cystic Fibrosis Foundation is that patients not undergo pleurodesis with the first pneumothorax. However, they recommended it be considered with recurrences. Surgical pleurodesis was preferred method. In cases of necrotizing pneumonia, initial treatment includes evacuation of the pleural space and antibiotic therapy. In asthma, treatment of the acute exacerbation and control of asthma is essential.

Chest tube management: Chest tubes can be small bore unless the rate of air leak is so great it exceeds the ability to suction it via the catheter. The catheter should be connected to a Heimlich valve or water seal. The use of suction is not routinely recommended due to the risk of post-expansion pulmonary edema. However, in cases where there is persistent air leak for more than 48 hours after drain placement without reexpansion of the lung, suction may be considered.

The British Thoracic Society adult guidelines advise using pressures -10 to -20 centimeters of water with a system capable of increasing capacity to 15-20 L per minute of suction. The risk of post-expansion pneumothorax is highest in younger patients with a large pneumothorax. Starting suction soon after chest tube insertion also increases the risk. A chest tube should remain in place until there has been no air leak for 12-24 hours. Some authors advocate clamping the chest tube prior to removal.

Indication for surgical consultation and possible surgical intervention for pneumothorax include: persistent air leak, second ipsilateral pneumothorax, first contralateral pneumothorax, bilateral pneumothoraces, spontaneous pneumothorax, at risk profession (pilot or diver) and pregnancy.

Surgical intervention: this may be indicated to treat an ongoing air leak or to attempt to prevent recurrence. Persistent air leaks may be treated by oversewing or stapling blebs or by apical resection. This has also been shown to be effective in preventing recurrence. In addition, mechanical pleural abrasion is also used in pediatric patients to prevent recurrences. These surgical procedures can be accomplished by video-assisted thoracoscopic surgery (VATS) or limited axillary thoracic surgery (LATS).

VATS has been shown to be safe and has been associated with decreased pain and length of treatment in pediatric patients with a similar recurrence rate compared to LATS. Chemical pleurocentesis is no longer commonly used in pediatrics because ot the associated pain. It may have a role in patients who are not surgical candidates but require treatment for persistent pneumothorax.

Pneumomediastinum: most cases of pneumomediastinum gradually resolved with only supportive care. Complete resolution typically occurs in 3 to 15 days. Recurrences are rare and are usually related to the underlying lung disease (such as asthma). In rare cases, there may be mediastinal compression requiring surgical intervention with mediastinotomy.

What are the adverse effects associated with each treatment option?

See above

What are the possible outcomes of a pneumothorax?

The best estimates are about 40-70% of patients managed with oxygen therapy, needle aspiration or chest tube drainage will not experience a recurrence of the pneumothorax. However, 30-60% of the patients will experience one or more recurrences which may require surgical intervention. The risk for recurrence appears to increase with each pneumothorax.

Most cases of pneumomediastinum gradually resolved with only supportive care. Complete resolution typically occurs in 3-15 days. Recurrences are rare and are usually related to the underlying lung disease, such as asthma. In severe cases, there may be mediastinal compression requiring surgical intervention.

What causes this disease and how frequent is it?

Peak age for pneumothorax is 16-24 years old
Higher risk in males (7-18/100,000) than females (6/100,000)
There is no known seasonal or geographic variation
Risk factors include:

Tall thin body habitus or low BMI

Smoking (tobacco or marijuana) or inhaling cocaine

Actvities that lead to Valsalva (lifting, defecating, balloon inflating, wind instruments, etc)

Medical conditions: CF, asthma, Marfan’s syndrome, Ehlers-Danlos, infection

Barotrauma: flying, diving, trauma, mechanical ventilation

Foreign body inhalation
A familial clustering of pneumothorax has been reported. The mechanism and pattern of inheritance have not been described.
Asymptomatic pneumothorax occurs in approximately 1- 2% of live births while symptomatic pneumothorax occurs in 2/10,000 births. Predisposing conditions for pneumothoraces in infants include congenital pulmonary disease (congenital cystic adenomatoid malformation, congenital lobar emphysema and mechanical ventilation).
The incidence of pneumomediastinum is difficult to ascertain. Estimates very widely from 1:800 to 1:42000 patients presenting to the hospital emergency room with respiratory symptoms.
Spontaneous pneumomediastinum has a bimodal distribution with a first peak between 6 months and 3 years of age. The majority are seen in older children and adolescents.
Additional risk factors for pneumomediastinum include bronchiolitis, vomiting, esophageal perforation and diabetic ketoacidosis (hyperpnea)

How do these pathogens/genes/exposures cause the disease?

Increased alveolar pressure is believed to lead to rupture of the alveoli in most cases. Causes include Valsalva maneuver associated with straining or heavy lifting, small airway obstruction due to inflammation or mechanical obstruction. Apical or peripheral blebs may rupture directly into the pleural space resulting in a pneumothorax. More centrally located alveoli may rupture into the lung interstitium. Air then tracks to the hilum causing pneumomediastinum. From there air may dissect along fascial planes and escape into the subcutaneous tissue of the neck, upper extremities, chest wall, cervical region, peritoneum or retroperitoneum. It may also rupture into the pleural space resulting in a pneumothorax or into the pericardium resulting in a pneumopericardium.

Apical blebs are a common finding in adults who have had a spontaneous pneumothorax, reported on CT scan or at the time of thoracoscoscopy in 90% of patients. They appear to be less common in pediatrics.

Other clinical manifestations that might help with diagnosis and management

If an pneumothorax is not immediately diagnosed and treated, the chest pain associated with it may become achy and gradually improve or resolve over 24 hours, even without resolution of the pneumothorax. Patients with small pneumothoraces may be asymptomatic.

What complications might you expect from the disease or treatment of the disease?

The most immediate and urgent complication is that of a tension pneumothorax or tension mediastinum. In the case of a tension pneumothorax, air fills the pleural space resulting in a shift of the mediastinum. It can compromise ventilation and cardiac output. It is characterized by respiratory distress, marked tachycardia and hypotension. Immediate treatment with needle aspiration of the accumulated air is indicated. Similarly, air may accumulate in the mediastinum interfering with normal circulation or respiration. This is rare but may require mediastinotomy.

Complications of treatment include:

– Conservative treatment: Worsening of respiratory status with need for chest tube drainage.

– Chest tube: Prolonged hospitalization, development of a bronchopleural fistula, infection, failure of pneumothorax to resolve, need for additional procedure.

– VATS: Intraoperative complications, need for open thoracotomy, need for prolonged use of chest tube postoperatively, pain, infection.

– LATS: intraoperative complications, need for prolonged use of a chest tube postoperatively, pain, infection.

– Chemical pleurodesis: Pain is the main risk. Hypercalcemia has been reported in infants treated with talc pleurodesis. Chemical pleurodesis may be a contraindication to lung transplantation.

Are additional laboratory studies available; even some that are not widely available?

No additional laboratory studies are required for diagnosis and treatment of a pneumothorax. An additional workup may be indicated if a condition which predisposed the child to the pneumothorax is suspected. In the case of a pneumomediastinum, an esophagram may be indicated if in the pneumomediastinum occurred after vomiting or in association with foreign body to rule out esophageal perforation or rupture. If there is a suspicion that asthma may have been a contributing factor, pulmonary function testing may be indicated but should not be performed in the immediate period after the pneumothorax or pneumomediastinum.

How can pneumothorax/pneumomediastinum be prevented?

For both of these entities, management of underlying lung conditions is essential. Patient should avoid smoking tobacco, marijuana, cocaine or anything else. They should avoid high risk activities for several weeks after their pneumothorax or pneumomediastinum. This would include things that require forced expiration like using a peak flow meter, pulmonary function testing or blowing up balloons for example.

Any activities that lead to a Valsalva maneuver should be avoided including activity such as weight lifting. Contact sport should be avoided. Although the peak risk for recurrence of the pneumothorax extends to the first year, published guidelines for air travel recommend not flying for at least one week after the resolution of the pneumothorax. In patients with cystic fibrosis, it is recommended that they avoid lifting and flying for 2 weeks.

People that have had a pneumomediastinum or pneumothorax should avoid diving unless they have had a definitive procedure to prevent recurrence. Similarly pilots who have had a pneumothorax, especially those who fly in unpressurized aircraft, should consider a surgical procedure to prevent recurrences.

What is the evidence?

McDuff, A, Arnold, A, Harvey, J. “Management of spontaneous pneumothorax: British Thoracic Society pleural disease guidelines 2010”. Thorax. vol. 65. 2010. pp. ii18-31. (These guidelines were developed using primarily adult references. However, they are the most evidence-based guidelines available. They include thorough discussions of evaluation and management with grades of evidence for each recommendation.)

Robinson, PD, Cooper, P, Ranganath, S. “Evidence-based management of paediatric primary spontaneous pneumothorax”. Paed Respir Rev. vol. 10. 2009. pp. 110-117. (This is an excellent review of previous series of patients with pneumothoraces. There are thorough discussions of various management options. However, the authors do not make specific recommendations themselves. There are extensive references.)

Chalumeau, M, LeClainche, L, Sayeg, N. “Spontaneous pneumomediastinum in children”. Pediatr Pulmonol. vol. 31. 2001. pp. 76-75. (This is a concise yet thorough overview of pneumomediastinum in children. It includes a review of previous series. There are excellent x-rays and diagrams. In addition, the authors have created an algorithm for managing these patients derived from the multiple case series available in the literature.)

Flume, PA, Mogayzel, PJ, Robinson, KA. “Cystic fibrosis pulmonary guidelines: Pulmonary complications: Hemoptysis and pneumothorax.”. Am J Respir Crit Care Med. vol. 182. 2010. pp. 298-306. (These are consensus based guidelines established using the Delphi method. They include comprehensive recommendations for the management of pneumothorax in patients with cystic fibrosis. There are extensive references and discussions supporting the rationale for these recommendations.)

Bauman, MH, Strange, C, Heffner, JE. “Management of spontaneous pneumothorax: An American College of Chest Physicians Delphi consensus statement”. Chest. vol. 119. 2001. pp. 590-602. (This is a set of adult guidelines developed as a consensus opinion using the Delphi method. Recommendations are straightforward. They do not address the pediatric population. There are extensive preferences.)

Sahn, SA, Heffner, JE. “Spontaneous pneumothorax”. NEJM. vol. 342. 2000. pp. 868-874. (This is a thorough review of spontaneous pneumothorax in adults. It is helpful in that it addresses a wide range of causes of secondary pneumothorax, although most of these are rare in pediatrics. The authors use available studies to make recommendations for management.)

Guimaraes, CVA, Donnely, LF, Warner, BA. “CT Findings for blebs and bullae in children with spontaneous pneumothorax and comparison with findings in normal age-matched controls”. Pediatr Radiol. vol. 37. 2007. pp. 879-884. (This study documented the high rate of blebs or bullae present in pediatric patients with spontaneous pneumothorax – 28% with ipsilateral blebs and 79% of those with contralateral blebs as well. All blebs noted on CT were apical suggesting that a limited CT focused on the apices could be used to look for blebs. No blebs or bullae were seen in age-matched controls. In addition, the authors noted the presence of "apical lines" on CT scan. They considered these to be a normal variant but felt they could be confused with blebs. These were present in 56% of pneumothorax patients and 28% of controls.)

Shih, CH, Yu, HW, Tseng, YC. “Clinical manifestations of primary spontaneous pneumothorax in pediatric patients: An analysis of 78 patients”. Pediatr Neonatol. vol. 52. 2011. pp. 150-154. (This is an interesting paper from Taiwan with findings in 78 patients that differ in some aspects from other series. There was a sriking male predominance of 88%. They reported an increase risk of pneumothorax in autumn. They had a very high rate of tension pneumothorax at 36%. Apical and subpleural blebs were found in 91% of patients. 42% experienced a second pneumothorax and 10% experienced a third. They also noted an increased risk with a low BMI.)

Chambers, A, Scarci, M. “In patients with the first episode primary spontaneous pneumothorax is video assisted thoracoscopic surgery superior to tube thoracostomy alone in terms of time to resolution of pneumothorax and incidence of recurrence?”. Interact Cardiovasc Thorac Surg. vol. 9. 2009. pp. 1003-1008. (This is an evidence-based review. The authors concluded that in adults, VATS had superior outcomes in terms of recurrence rate of pneumothorax, duration of chest CT drainage and mean hospital stay with the first episode of spontaneous pneumothorax compared with conservative treatment. It can be contrasted with the study by Quershi in a pediatric population.)

Quereshi, FG, Sandulache, VC, Richardson, W. “Primary versus delayed surgery for spontaneous pneumothorax in children: Which is better?”. J Pediatr Surg. vol. 40. 2005. pp. 160-169. (This is a retrospective review of 54 episodes of spontaneous pneumothorax in 43 pediatric patients performed with the hypothesis that primary surgical intervention is a safe and effective management strategy for patients presenting with an spontaneous pneumothorax. While there was higher morbidity and cost for those patients who failed conservative management and subsequently required a VATS, 46% of patients were successfully managed without surgical intervention. When a financial analysis was performed, it was found that a recurrence rate of 72% would be required to financially justify primary VATS on all patients presenting with a spontaneous pneumothorax.)

Huang, TW, Lee, SC, Cheng, YL. “Contralateral recurrence of primary spontaneous pneumothorax”. Chest. vol. 132. 2007. pp. 1146-1150. (This represents a 3-year experience at one institution. It includes 231 patients with primary spontaneous pneumothorax ranging in age from 16-35 years old. 50% of them were smokers and 92% were male. 14% experienced a contralateral pneumothorax. There was no gender difference in risk of contralateral recurrence. Recurrence was associated with a lower BMI. The average time to recurrence was 22.9 months. All with recurrent pneumothoraces had blebs or bullae.)

Weissberg, D, Refaely, Y. “Pneumothorax experience with 1199 patients”. Chest. vol. 117. 2000. pp. 1279(This is a retrospective review of patient's with pneumothorax of diverse etiologies. The patient's reached any range in age from 11-80 years old. It does include a useful algorithm for management of patients presenting with a clinical diagnosis of pneumothorax. This is based on the extensive experience at one institution but is in close agreement with the recommendations from other sources.)

Ongoing controversies regarding etiology, diagnosis, treatment

There is an absence of controlled clinical trials involving management of pneumothoraces, especially in the pediatric population. There are many unanswered questions including:

How is the size of the pneumothorax best estimated?

What size pneumothorax can safely be managed conservatively?

How long does a pediatric patient managed conservatively need to be observed in the hospital before discharge?

What are the indications for surgical intervention?

How long should chest tube drainage be continued before surgical intervention?

After how many recurrences should surgical intervention be considered?

What is the best approach for surgical intervention, VATS or LATS?

At the present time, the answers to these questions will depend on the facilities available at the point of care, the expertise of the intensivist and the surgeons and the preferences of the patient.

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