Case Based Pediatrics For Medical Students and Residents
Department of Pediatrics, University of Hawaii John A. Burns School of Medicine
Chapter XIV.7. Pneumothorax and Other Air Leaks
Edward W. Fong, MD
September 2002

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A father brings his 8 year old daughter into your office because "she is not able to catch her breath". He reports that she has just recently recovered from a cold, but has continued to cough. She often coughs in fits with post-tussive emesis, will sometimes turn blue in the face, and makes a "gasping-like" noise when she tries to inhale after a coughing episode. Currently, she complains about a pain in her chest and shortness of breath. According to her father, the onset of these symptoms began "after one of those coughing fits this morning". There is an ill contact in the house (a grandfather who has been coughing for the last 3 months).

Exam: VS T 37.1, HR 94, RR 28, BP 115/77, Oxygen saturation 93-95% in RA, height is 50-75th %ile, and her weight and head circumference are both in the 10-25th %ile. She is sitting on the exam table, leaning forward, taking quick breaths with some nasal flaring. She has slightly asymmetrical chest movements (her right chest wall moves less than her left) and she has decreased breath sounds with hyper-resonance and decreased tactile fremitus on the right as well. Her PMI and trachea are normally positioned, her sensorium is normal, and she has regular and symmetrical radial and femoral pulses. Since you suspect a pneumothorax, your nurse places the patient on 2 liters/minute 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 that her oxygen saturation is 100% on the 2 liters/minute of oxygen. She is switched to a non-rebreather mask with a FiO2 of 100% and sent for a PA and lateral CXR. Upon confirmation by the radiologist, she is diagnosed with a right, simple, primary spontaneous pneumothorax. It is estimated to be about 12% in size. She is admitted to the hospital for observation and continued oxygen therapy. She remains clinically stable overnight and her follow-up morning CXR showed a small decrease in the size of the pneumothorax. She is then taken off of oxygen and has another CXR performed the following morning. Although this CXR does not show any further decrease in the size of the pneumothorax, it had not increased. She is discharged home with instructions to follow-up with you the next day.


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 hard to determine. The best estimates exist for pneumothoraces. From a study of Minnesota residents between 1959 and 1978, it has been estimated by extrapolating the data, that about 9000 people in the United States develop a primary spontaneous pneumothorax annually (1). In a recent 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 and accounts for nearly $1.3 million in health care expenditures annually (2). Pneumothoraces are also found in about 5% of hospitalized asthmatic children and about 10-25% of cystic fibrosis patients older than 10 years old (3).

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 with a gas-producing microorganism (4). The type of air leak syndrome that develops will depend on the location and the nature of the communication. Although air leaks can be caused spontaneously, the majority of them are secondary to some type of trauma (intentional, accidental, mechanical, and iatrogenic). A retrospective case review by Kizer et al. found that over a 5 year period, 95% of patients who developed a pneumothorax while engaged in an outdoor sport had blunt chest trauma as the etiology (5). 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) (4). 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 (6). Pneumothoraces are categorized as spontaneous or traumatic and classified as simple, communicating, or tension (1,7). 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 (COPD, 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. A communicating pneumothorax ("sucking chest wound") occurs when there is an associated defect in the chest wall (7). 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 (7). Communicating and tension pneumothoraces may result in the rapid onset of hypoxia, acidosis, and shock.

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 (4,6). 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 (6). Ipsilateral shoulder pain is common. 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 may be present in any type of air leak syndrome, which sounds like a fine rub (similar to Velcro). Hamman's sign is often 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 not very common even with tension pneumothoraces.

The diagnosis of a pneumothorax should be confirmed by radiographs. Two views, AP and lateral, should be obtained. These may be supplemented by a cross-table lateral or lateral decubitus views. Expiratory views may help to visualize a small pneumothorax. 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 unless it is a recurrent primary spontaneous pneumothorax or a secondary spontaneous pneumothorax.

The treatment of a pneumothorax is determined by its classification. A tension pneumothorax usually results in cardiopulmonary compromise (shock, bradycardia, hypoxia) requiring immediate needle decompression (thoracentesis), which can be accomplished by inserting a large bore (16 or 18 gauge) needle (smaller gauge needles are satisfactory for premies, newborns and infants) through the second or third interspace (near the apex of the lung) in the midclavicular line. Immediate decompression cannot wait for radiographic confirmation. In fact it is often said, that if you see a tension pneumothorax on a CXR, the patient may already be dead or you are NOT looking at a tension pneumothorax, but something that is mimicking one instead. Tube thoracostomy (commonly called a chest tube) may be required after the initial decompression if the pneumothorax reaccumulates. A communicating 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, but this must be done with caution as it can cause the development of a tension pneumothorax. Once the patient is in a hospital setting, he/she should be intubated and tube thoracostomy performed until she can be taken for definitive surgical repair.

There are two instances when a tension pneumothorax tends to occur more commonly: 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 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 ACCP Consensus Statement for primary spontaneous pneumothoraces, clinically stable patients with a small pneumothorax (occupying <15% of the hemithorax) (1) 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 (2). If the patient is to be admitted to the hospital, oxygen therapy may be initiated since 100% oxygen 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 (2). 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 choice (2). 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 (2).

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 bullectomy 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 (40-87%), especially if the initial episode was slow to resolve (>7 days) or if the underlying disorder is not corrected (4). Activities that involve rapid or profound changes in barometric pressure (scuba diving, flying in unpressurized aircraft, etc.) should be avoided.

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. If associated with respiratory distress, the air leaks signify a 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 between:
. . . . . a. the second and third interspace in the midaxillary line
. . . . . b. the fourth and fifth interspace in the midclavicular line
. . . . . c. either a or b
. . . . . d. neither a or b

3. List the different categories and classifications of pneumothoraces.

4. Pick the two conditions which you would most likely to encounter a tension pneumothorax:
. . . . . a. NICU ventilator patient for RDS.
. . . . . b. Near drowning patient on blow-by oxygen.
. . . . . c. Hydrocarbon aspiration.
. . . . . d. Blunt chest trauma.
. . . . . e. Stab wound to the mid lateral torso.

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

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


Related x-rays

Pneumothorax case: 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. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v3c13.html

Pneumomediastinum case: Butts RJ. Hamman's Sign. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1994, volume 1, case 7. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v1c07.html

Pneumomediastinum case: Yamamoto LG. Chest Pain in a 6 Year Old. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1996, volume 6, case 12. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v6c12.html


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. 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.

3. Orenstein DM. Chapter 419-Pneumothorax. In: Behrman RE, Kliegman RM, Jenson HB (eds). Nelson Textbook of Pediatrics, 16th edition. 2000, Philadelphia: W.B. Saunders Co, pp. 1331-1332.

4. Montgomery M. Chapter 17-Air and Liquid in the Pleural Space. In: Chernick V, Boat TF (eds). Kendig's Disorders of the Respiratory Tract in Children, sixth edition. 1998, Philadelphia: W.B. Saunders Co, pp. 389-411.

5. Kizer KW, MacQuarrie MB. Pulmonary Air Leaks Resulting from Outdoor Sports: A Clinical Series and Literature Review. Am J Sports Med 1999;27(4):517-520.

6. Panitch HB, Papastamelos C, Schidlow DV. Chapter 76-Abnormalities of the Pleural Space. In: Taussig LM, Landau LI (eds). Pediatric Respiratory Medicine. 1999, Carlsbad: Mosby, pp. 1178-1196.

7. Eckstein M, Henderson S, Markovchick V. Chapter 38-Thorax. In: Marx JA (editor). Rosen's Emergency Medicine: Concepts and Clinical Practice, fifth edition. 2002, St. Louis: Mosby, pp. 386-391.

8. Brown MA. Personal Communication. 2002.


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

4. a & e. Tension pneumothorax is most likely to occur on ventilator patients and hose with penetrating chest trauma. A stab wound to the lateral mid thorax is very likely to have entered the lower thorax.

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

6. d.


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