Chapter XIV.7. Pneumothorax and Other Air Leaks
Edward W. Fong, MD
July 2014

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A 15 year-old young man arrives into your office after having a day of chest pain that will not go away. He reports that he had been riding home on the bus yesterday when it stopped suddenly, and he had to put his hands out in front of him to brace himself for the impact. He reports that on impact, he only hit the seat with his hands/arms, and it was not until 10 to 15 minutes later after he had walked halfway home that he suddenly felt a sharp pain in his chest. He reports that the pain continued throughout all cycles of respiration, but if he stopped walking and took smaller breaths, it did not hurt as much. He thought he just pulled a muscle and continued home. He remembered that this had happened once before about a year ago, but the pain had gone away by the next day so he did not tell his parents. Upon awakening this morning, the pain was only a dull ache, but he couldn't get comfortable in any position. He finally told his parents, and they brought him to your office.

Exam: VS: T 36.5, HR 87, RR 21, BP 115/77, oxygen saturation 95% to 97% in RA, height is 75th%ile, and weight is 20th%ile. He is sitting on the exam table in no acute distress, but you notice he is taking quick shallow breaths and avoids deep inhalations unless prompted on exam. He has slightly asymmetrical chest movements (his right chest wall moves less than his left), and he has decreased breath sounds with hyper-resonance and decreased tactile fremitus on the right as well. His heart PMI and trachea are normally positioned, his sensorium is normal, and he has regular and symmetrical radial and femoral pulses. Since you suspect a pneumothorax, your nurse places the patient on 2 liters per minute (LPM) of oxygen via nasal cannula while you arrange for medical transport to the Emergency Department.

Upon arrival at the ED, the patient's vitals are relatively unchanged, except his oxygen saturation is now 100% on the 2 LPM of oxygen. He is switched to a non-rebreather mask to attain an FiO2 closer to 1.0 and is sent for a PA and lateral CXR. Upon confirmation by the radiologist, he is diagnosed with a right, simple, primary spontaneous pneumothorax. It is estimated to be about 30% in size, so a percutaneous chest tube is placed in the ED and connected to wall suction at -20 cmH2O pressure. A post-procedure CXR is performed and proper chest tube placement is confirmed as well as a decrease in size of the pneumothorax with only a small residual apical collection of air remaining. He is admitted to the hospital for further evaluation and management, including a CT scan of his chest for blebs as well as an evaluation for genetic syndromes in light of his body habitus and history of prior symptoms.


Air leak syndromes encompass a wide-spectrum of diseases including pneumomediastinum, pneumothorax, pneumopericardium, pneumoperitoneum, subcutaneous and interstitial emphysema, and pulmonary pseudocyst. Due to the pathophysiology of air leak syndromes, more than one of these disease processes are often present concomitantly. The exact prevalence and incidence of the differing air leak syndromes is difficult to determine. The best estimates exist for primary spontaneous pneumothoraces. There are two studies that have been used to extrapolate an annual incidence of occurrence in the United States. The first estimate of 9000 occurrences annually in the United States is from a study of Minnesota residents between 1959 and 1978 (1), while the second estimate of 22,500 people annually in the United States (2) was extrapolated from data from a study of English citizens between 1991 and 1995 (3). In the 2001 American College of Chest Physicians (ACCP) Delphi Consensus Statement, it is estimated that, in the United States, both primary and secondary spontaneous pneumothoraces affect more than 20,000 patients (4). Pneumothoraces are also found in about 5% of hospitalized asthmatic children and about 10% to 25% of cystic fibrosis patients older than 10 years old (5).

Thoracic air leak syndromes result from a free communication with the atmosphere, either from a pleura defect or from alveolar rupture. They are rarely caused by infection from a gas-producing microorganism (6). The type of air leak syndrome that develops will depend on the location and the nature of the communication as well as the type/classification of pneumothorax. Primary spontaneous pneumothoraces typically occur at rest (7), and both primary and secondary spontaneous pneumothoraces have been associated or attributed to a number of risk factors including undiagnosed pulmonary blebs, smoking (tobacco and cannabis) and certain habitus forms (8). The mechanism of alveolar air leaks begins with positive intra-alveolar inflation pressure causing an increase in the air volume of the alveolus with a simultaneous decrease in the blood volume of the adjacent alveolar blood vessels. The difference between the changes in these respective volumes causes an attenuation of the tissue that tethers the perivascular sheath to the alveolar wall. When the traction force exceeds the tissue's tensile strength, a rupture of the base of the alveoli occurs allowing gas to escape into the perivascular space. The escaping air may then dissect along perivascular planes into the mediastinum (pneumomediastinum), into the pericardium (pneumopericardium), into the pleural space (pneumothorax), into the peritoneal cavity (pneumoperitoneum), out of the thorax along subcutaneous tissue planes (subcutaneous emphysema), and/or be confined to the interstitium of the lung (interstitial emphysema) (6). Since pneumothoraces are the most common type of air leak syndrome, the rest of the discussion will concentrate on this entity.

A pneumothorax is defined as the abnormal presence of air in the pleural space. Pneumothoraces are categorized as spontaneous or traumatic and classified as simple, communicating (or open), and tension (3,9). Spontaneous pneumothoraces should be further categorized as primary or secondary. A primary pneumothorax occurs in an otherwise healthy person without underlying disease (rupture of a subpleural emphysematous bleb), while a secondary pneumothorax occurs as a complication of an underlying lung disease (e.g., chronic obstructive pulmonary disease, cystic fibrosis, tuberculosis, asthma) (1). Traumatic pneumothoraces may be caused by penetrating or blunt trauma, mechanical ventilation, central line placement, or toxic inhalations. A simple pneumothorax occurs when there is an accumulation of air without any communication to the atmosphere and without causing a shift of the mediastinum or hemidiaphragm. An open pneumothorax (sucking chest wound) occurs when there is penetration and communication through the chest wall (9). This defect may cause paradoxical chest wall movement (collapse during inhalation and expansion during exhalation) along with the sonorous sound of air entering and exiting the wound. A tension pneumothorax occurs when the progressive accumulation of air causes a shift of the mediastinum to the opposite hemithorax causing a subsequent compression of the contralateral lung and great vessels (8). Communicating and tension pneumothoraces may result in the rapid onset of hypoxia, acidosis, and cardiovascular collapse (severe hypotension and bradycardia).

Although the cardinal manifestation of a pneumothorax is the sudden onset of chest pain, symptoms will vary depending on the extent of lung collapse, degree of intrapleural pressure, rapidity of onset, age, and respiratory reserve of the patient (6, 10). Symptoms that may be present include: tachypnea, dyspnea, tachycardia, and cyanosis. The chest pain may range from a localized sternal pain to an overwhelming pleuritic pain difficult to localize (10). Ipsilateral shoulder pain is common. On auscultation, there is usually a decrease in breath sounds, tactile fremitus, and a decrease in thoracic excursion while there is an increase in resonance to percussion on the affected side. Hamman's sign is a transient and rare auscultatory finding associated with pneumothorax and pneumomediastinum, that sounds like grating or snow crunching, sometimes mistaken for a pericardial friction rub. If a tension pneumothorax is present, displacement of the trachea and PMI toward the contralateral side may occur as well as rapid deterioration with hypotension and bradycardia. In young children, tracheal displacement is uncommon even with tension pneumothoraces.

The diagnosis of a pneumothorax should be confirmed by radiographs. Two views, PA and lateral, should be obtained. These may be supplemented by a cross-table lateral or lateral decubitus view. It is commonly taught that a pneumothorax is more easily identified on an expiratory chest radiograph but it does not provide any additional benefit in the routine assessment for pneumothorax (11). Radiographs will help to differentiate a pneumothorax from emphysema, an emphysematous bleb, diaphragmatic hernia, compensatory overexpansion, large pulmonary cavities, contralateral atelectasis, or other cystic formations. A CT scan is not necessary for initial diagnosis unless further differentiation of pathology or accurate size calculations are required (11), but it should be noted that the size of a pneumothorax is less important than the degree of clinical compromise (11). Pneumothorax can be identified on ultrasound with a high sensitivity.

The management of a pneumothorax is determined by its classification. A tension pneumothorax requires immediate decompression, which can be accomplished by inserting a large bore (16 or 18 gauge) needle (smaller gauge needles are satisfactory for premies and infants) through the second or third interspace (near the apex of the lung) immediately superior to the rib and along the midclavicular line. If a patient is exhibiting cardiopulmonary compromise from a suspected tension pneumothorax (e.g., shock, bradycardia, hypoxia, cyanosis, etc.), immediate needle decompression should be performed rather than waiting to confirm the diagnosis with a chest x-ray. Tube thoracostomy (commonly called a chest tube) may be required after the initial decompression if the pneumothorax reaccumulates. A communicating or open pneumothorax should have the defect covered immediately, which helps to convert the condition to a simple pneumothorax. An occlusive dressing using petroleum gauze may be applied until definitive surgical repair can be undertaken, but this must be done with caution as it can cause the development of a tension pneumothorax.

Simple pneumothoraces can be treated with percutaneous aspiration, tube thoracostomy, or the insertion of percutaneous drainage devices commonly called pig-tailed catheters. Some or perhaps many simple pneumothoraces can resolve on their own. A chest tube is commonly attached to suction to expand the collapsed lung, reducing the size of the pneumothorax. An alternative is to attach a Heimlich valve to the chest tube, which gradually reduces the pneumothorax size in most instances with spontaneous breathing and chest movement. While many adult patients with stable pneumothoraces can be discharged from the ED with a chest tube and Heimlich valve, this is less commonly done with pediatric pneuthoraces. If a child requires prolonged evacuation of air via chest tube, hospital admission is warranted.

A tension pneumothorax requires a prompt clinical diagnosis and immediate decompression. Treatment cannot usually wait for X-ray confirmation because of rapid deterioration. There are two instances when a tension pneumothorax tends to occur more commonly than in others: 1) positive pressure ventilation (i.e., in the ICU on a ventilator), and 2) external penetrating trauma (knife or bullet wound to the chest). The mechanics of this involve a one-way valve effect of the air leak. A positive pressure ventilator pushes air into the pleural space through the leak, while during exhalation the leak valve closes and does not permit the pleural air to escape. A penetrating wound to the chest may produce a slit into the pleural space, which sucks air into the chest when the patient inhales, but this air is trapped in the pleural space because the slit closes when the patient exhales. While a tension pneumothorax can occur in other conditions, it is largely these two conditions in which you are most likely to encounter a tension pneumothorax.

Management of a simple pneumothorax depends on its size and etiology. According to the 2001 ACCP Consensus Statement for primary spontaneous pneumothoraces, clinically stable patients with a small pneumothorax (<3 cm apex of the lung to apex of the hemi-thorax distance determined by upright standard radiograph) should be observed in the emergency department for 3 to 6 hours and discharged home if: 1) a repeat CXR demonstrates no progression of the pneumothorax, 2) the patient does not live a far distance from emergency services, and 3) there is reliable follow up care (4). Although, the 2010 British Thoracic Society's Pleural Disease Guideline concurs with this management of a small, stable pneumothorax, it differs on the differentiation between large vs. small pneumothorax. It recommends using a CT scan of chest and defines a small pneumothorax as being <2 cm distance between lateral lung edge and lateral chest wall (11).

If the patient is to be admitted to the hospital without surgical intervention, oxygen therapy via non-rebreather mask should be initiated in order to attain an environment of 100% oxygen, which theoretically will hasten the absorption of the pneumothorax (possibly by eventually enriching the pneumothorax with oxygen, which is more soluble in blood). Clinically stable patients with a large primary spontaneous pneumothorax should be admitted to the hospital and undergo tube thoracostomy (4). The chest tube should not have negative pressure applied immediately, but rather it should initially be put to water seal to allow the trapped air to exit slowly. This precaution is done to avoid rapid reexpansion of the lungs, which can result in pulmonary edema.

The ACCP Consensus Statement for clinically stable patients with a small, secondary spontaneous pneumothorax recommends that these patients should all be hospitalized. The decision between observation and tube thoracostomy depends on the extent of the patient's symptoms, course of the pneumothorax, and practitioner preference (4). Clinically stable patients with a large secondary spontaneous pneumothorax should be treated similarly to the clinically stable patients with a large primary spontaneous pneumothorax. Any clinically unstable patient with a pneumothorax of any size should be immediately stabilized, decompressed, and hospitalized (4).

Procedures to prevent the recurrence of a pneumothorax should be reserved for secondary spontaneous pneumothoraces, a second episode of a primary spontaneous pneumothorax, or the persistence of an air leak regardless of whether or not it is the first episode of a pneumothorax. The procedure to prevent recurrence often involves excision of pulmonary bullae and/or pleurodesis usually through video-assisted thoracoscopy. However, the practitioner of a patient who may require lung transplantation in the future should consider consulting with the potential transplant team before undertaking pleurodesis.

The recurrence of spontaneous pneumothorax is common (40% to 87%), especially if the initial episode was slow to resolve (>7 days) or if the underlying disorder is not corrected (6). Activities that involve rapid or profound changes in barometric pressure (e.g., scuba diving, flying in unpressurized aircraft, etc.) should be avoided at least in the short term.

Pneumomediastinum and subcutaneous emphysema in the neck region are usually benign conditions if the patient is only minimally symptomatic, but they may precede a pneumothorax in some instances. They often occur in association with patients in status asthmaticus. If associated with respiratory distress, the air leaks signify higher risk. Pneumopericardium is associated with cardiac tamponade and a high risk of mortality even if decompression is attempted.


Questions

1. True/False: A primary spontaneous pneumothorax in a tall thin boy does not require further work-up other than for treatment of the pneumothorax.

2. In order to emergently decompress a tension pneumothorax, one should insert a large bore needle through:
. . . . . a. the second or third interspace in the midclavicular line
. . . . . b. the fourth or fifth interspace in the midaxillary line
. . . . . c. either a or b
. . . . . d. neither a or b

3. How does the administration of 100% oxygen help with the reabsorption of a pneumothorax?

4. List the different categories and classifications of pneumothoraces.

5. In order for a patient to receive 100% oxygen, one must use:
. . . . . a. Simple face mask
. . . . . b. Nasal cannula
. . . . . c. Non rebreather mask
. . . . . d. Blow-by

6. How is the size of a pneumothorax determined?

7. True/False: A chest tube is always the standard of care for the treatment of a pneumothorax.

8. A sucking chest wound refers to what kind of air-leak syndrome?
. . . . . a. Interstitial emphysema
. . . . . b. Simple pneumothorax
. . . . . c. Tension pneumothorax
. . . . . d. Communicating/open pneumothorax
. . . . . e. Pneumomediastinum


Related X-rays


Pneumomediastinum in a teen presenting with chest pain and Hamman's sign. Arrows in the PA view identify vertical air densities and a triangular aortopulmonary window. Arrows in the lateral view identify air dissecting around the trachea and air densities in the mediastinum.
Butts RJ. Hamman's Sign. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1994, volume 1, case 7. Read the online case and description at: www.hawaii.edu/medicine/pediatrics/pemxray/v1c07.html



Subtle pneumomediastinum. Arrows in the PA view identify vertical air densities. Arrows in the lateral view identify vertical air densities in the mediastinum and air dissecting around the trachea.
Yamamoto LG. Test Your Skill In Reading Pediatric Chest Radiographs. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1995, volume 3, case 20F. Read the online case and description at (see Case F): www.hawaii.edu/medicine/pediatrics/pemxray/v3c20.html



Pneumomedistinum in a 6 year old. Arrows on the PA view point out vertical air densities in the patient's neck (subcutaneous emphysema). Arrows in the lateral view identify air dissection in the anterior chest and air dissecting around the trachea.
Yamamoto LG. Chest Pain in a 6 Year Old. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1999, volume 6, case 12. Read the online case and description at: www.hawaii.edu/medicine/pediatrics/pemxray/v6c12.html



Small pneumothorax seen on CXR and CT. The arrow on the CT scan shows the edge of the lung and the adjacent air within the pleural space. The arrows on the enlarged CXR PA view show the edge of the lung.
Yamamoto LG. Acute Chest Pain in a Tall Slender Teenager. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1995, volume 3, case 13. Read the online case and description at: www.hawaii.edu/medicine/pediatrics/pemxray/v3c13.html



Pneumopericardium. Air is within the pericardial sac. The air visualizes the inferior margin of the thymus causing bilater "sail signs".
Yamamoto LG. Test Your Skill In Reading Pediatric Chest Radiographs. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1995, volume 3, case 20K. Read the online case and description at:(see Case K): www.hawaii.edu/medicine/pediatrics/pemxray/v3c20.html



Left image shows a left pneumothorax and pulmonary interstitial emphysema. The right image shows another case of pulmonary interstitial emphysema.
Series of neonatal CXRs including pneumothorax and pulmonary insterstitial emphysema: Yamamoto LG. Radiology Cases in Neonatology, 1996. Review the series of x-rays online at: www.hawaii.edu/medicine/pediatrics/neoxray


References

1. Light RW, Broaddus VC. Chapter 75-Pneumothorax, Chylothroax, Hemothorax and Fibrothorax. In: Murray JF, Nadel JA (eds). Textbook of Respiratory Medicine, third edition. 2000, St. Louis: W.B. Saunders Co, pp. 2043-2051.

2. Light RW, Lee YCG. Chapter 74-Pneumothorax, Chylothroax, Hemothorax and Fibrothorax. In: Mason RJ, Broaddus, VC (eds). Murray & Nadel's Textbook of Respiratory Medicine, fifth edition. 2000, St. Louis: W.B. Saunders Co, pp. 1764-1791.

3. Gupta D, Hansell A, Nichols T, et al. Epidemiology of pneumothorax in England. Thorax 2000;55:666-671.

4. Baumann MH, Strange C, Heffner, JE, et al. Management of Spontaneous Pneumothorax: An American College of Chest Physicians Delphi Consensus Statement. Chest 2001;119(2):590-602.

5. Winnie GB, Lossef SV. Chapter 405-Pneumothorax. In: Kliegman RM, Stanton BF, Schor NF (eds). Nelson Textbook of Pediatrics, 19th edition. 2011, Philadelphia: W.B. Saunders Co, pp. 1509-1512.

6. Montgomery M. Chapter 70-Air and Liquid in the Pleural Space. In: Wilmott RW, Boat TF, et al (eds). Kendig and Chernick's Disorders of the Respiratory Tract in Children, eight edition. 2012, Philadelphia: W.B. Saunders Co, pp. 976-994.

7. Baumann MH, Noppen M. Pneumothorax. Respirology 2004;9:157-164.

8. Dotson K, Johnson LH. Pediatric Spontaneous Pneumothorax. Pediatr Emer Care 2012;28:715-723.

9. Manthey DE, Nicks BA. Chapter 51-Pneumothorax. In: Adams JG (ed). Emergency Medicine, second edition. 2013, Philadelphia: Saunders, pp. 423-430.

10. Tauber D, Schidlow DV. Chapter 68-Abnormalities of the Pleural Space. In: Taussig LM, Landau LI (eds). Pediatric Respiratory Medicine second edition. 2008, Philadelphia: Mosby, pp. 989-997.

11. MacDuff A, Arnold, A, Harvey, J. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax 2010;65 (Suppl 2):ii18-ii31.


Answers to questions

1. False. A patient with this type of body habitus should have a work-up that includes looking for a connective tissue disorder such as Marfan's syndrome.

2. d. It is the second or third interspace in the midclavicular line or the fourth or fifth interspace in the midaxillary line.

3. The theory is that by providing an environment of 100% oxygen, the pneumothorax will eventually be washed out of all other gasses leaving the highly soluble oxygen to be reabsorbed into the blood stream, thus decreasing the size of the pneumothorax.

4. Categories: Spontaneous and traumatic. Subcategories: Primary and Secondary. Classifications: Simple, Communicating, and Tension.

5. b. Short of intubation and mechanical ventilation, the only way to provide an environment close to 100% oxygen is to administer it via a non-rebreather mask.

6. There are two methods: 1) 2001 ACCP guidelines recommend determining the distance between lung apex and the cupola (chest apex) on standard upright CXR. If the distance is <3 cm = small and if distance >=3 cm = large; and 2) 2010 BTS guidelines recommend determining distance between lung edge and chest wall on CT scan of chest. If the distance is <2 cm = small and if distance >=2 cm = large.

7. False. Treatment depends on the classification of pneumothorax.

8. d. Communicating/open pneumothorax


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