spontaneous pneumothorax and pneumomediastinum

7/30/2019 Spontaneous Pneumothorax and Pneumomediastinum

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Spontaneous Pneumothorax and PneumomediastinumSusan M. Dunmire

Spontaneous pneumothorax and pneumomediastinum are relatively uncommon entities in

emergency medicine; however, it is important for the emergency department physician to befamiliar with the presentation and management of these conditions.

A pneumothorax is defined by the presence of gas within the pleural space. A pneumothorax

occurring in the absence of penetrating or blunt injury to the chest wall is termed a spontaneouspneumothorax. This can be classified either as primary, occurring in patient without known

pulmonary disease, or as secondary, occurring in the setting of underlying lung disease. A

tension pneumothorax occurs when a large accumulation of air in the pleural space impairsvenous return, thereby resulting in hypotension.

Although most authorities agree that a spontaneous pneumothorax is the result of rupture of

small subpleural cysts or blebs, the etiology of these structural abnormalities (congenital versus

acquired) is still controversial. In individuals with a primary spontaneous pneumothorax,computed tomographic (CT) scan demonstrates ipsilateral bullae in 89% of patients compared

with 20% of controls matched for age and smoking history (11,14). In a review of 11 studies, the

average recurrence rate of a spontaneous pneumothorax is 30% (range, 16% to 52%) (19).A primary spontaneous pneumothorax typically occurs in tall, thin individuals younger than theage of 40 years, with a male-to-female ratio of 5:1 (15,17). The incidence of primary

spontaneous pneumothorax is between 7.4 and 18 cases in 100,000 for male patients and

between 1.2 and 6 cases per 100,000 for female patients (3,13). Cigarette smoking significantlyincreases the risk of a primary spontaneous pneumothorax by as much as 20-fold (3,8).

The incidence of secondary spontaneous pneumothorax in individuals with known chronic

obstructive pulmonary disease (COPD) is approximately 26 in 100,000 (7). The peak age for

occurrence of a secondary pneumothorax is 60 to 65 years, and the most common underlying riskfactor is COPD. Secondary spontaneous pneumothorax occurs in 2% to 6% of patients with

human immunodeficiency virus (HIV) and concurrent Pneumocystis carinii pneumonia

(2,4,12,18). Other less common causes of secondary pneumothorax include malignancy, asthma(sometimes presenting as sudden severe respiratory compromise), pulmonary infarction,

histiocytosis X, and Hamman-Rich syndrome (acute interstitial pulmonary fibrosis).

Another less common but interesting entity is catamenial pneumothorax. This is a spontaneous

pneumothorax occurring in women at the time of menstruation. This entity typically affectswomen in the age range of 30 to 40 years and occurs within 72 hours of the onset of menses (10).

A catamenial pneumothorax is frequently right-sided and has a 50% recurrence rate within the

first year. Although its etiology is multifactorial, in some patients the condition results fromsmall implants of endometrial tissue in the pleural lining (5,9,21).

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Spontaneous pneumomediastinum is the result of alveolar rupture with dissection of air along the

bronchus and into the mediastinum. The cause of pneumomediastinum often cannot be

identified. Although it is usually a benign entity, more serious causes such as esophageal rupturemust be ruled out. A pneumomediastinum can occur in patients with a history of vigorous

vomiting or in those who use repetitive and prolonged Valsalva maneuvers to enhance the effects

of inhaled pipe-smoked cocaine (20).CLINICAL PRESENTATION


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Patients with spontaneous pneumothorax typically present with the sudden onset of constant,

ipsilateral chest or shoulder pain that may or may not increase with inspiration. The majority of

patients complain of dyspnea, although the severity depends on the size of the pneumothorax.Patients with a secondary spontaneous pneumothorax will often present with severe dyspnea,

even with a small pneumothorax, owing to the degree of underlying pulmonary disease. The

onset of symptoms usually occurs at rest or during sleep. Rarely, spontaneous pneumothorax canpresent as a tension pneumothorax with severe cardiopulmonary compromise.Symptoms in adults with spontaneous pneumomediastinum include retrosternal chest pain and,

less frequently, subcutaneous emphysema caused by tracking of air into the chest wall, neck,

face, abdominal wall, and scrotum. If enough air accumulates in the mediastinum, the pleura canrupture, resulting in an associated pneumothorax. Spontaneous pneumomediastinum in infants is

a much more serious entity and can cause cardiopulmonary compromise by compression of the

hilum (23).

DIFFERENTIAL DIAGNOSISPulmonary embolism, exacerbation of COPD or asthma, pneumonia, and myocardial ischemia

should all be in the differential diagnosis of a patient with shortness of breath and chest pain.

Often the entity of spontaneous pneumothorax is not considered until the chest radiograph isobtained.

Once the diagnosis of pneumothorax has been made, the physician is obligated to search for the

underlying cause. In the case of spontaneous pneumothorax, it is important to reevaluate the

history and physical examination to ensure that there is no sign of blunt or penetrating trauma.An elderly person may have forgotten a recent fall, resulting in rib fractures and an underlying

pneumothorax. A puncture site in the neck or supraclavicular area can easily be missed in a

patient who is an unsuspected drug abuser who has penetrated the pleural space.Spontaneous pneumomediastinum usually presents as substernal chest pain. The differential

diagnosis includes myocardial ischemia, gastroesophageal reflux, pulmonary embolism, and

pneumonia.

EMERGENCY DEPARTMENT EVALUATIONPhysical examination is often not very helpful in making the diagnosis of spontaneous

pneumothorax. Patients often exhibit mild resting tachycardia and tachypnea. Depending on the

extent of the pneumothorax, breath sounds may be diminished unilaterally. The presence ofhypotension and tachycardia (>140 beats per minute) in combination with jugular venous

distention or tracheal deviation should immediately alert the emergency physician to the

possibility of a tension pneumothorax requiring emergent decompression.The diagnosis of pneumothorax is usually made by chest radiography (CXR), which reveals a

peripheral lucent area containing no lung markings. Films taken in maximal expiration with the

patient in an upright position optimize visualization of small pneumothoraces. The size of a

pneumothorax may be roughly gauged from the plain chest film, but such estimates arenotoriously unreliable. Algorithms that yield more accurate estimates of size are available but are

relatively complicated to apply (16).

Patients with a significant (>25%) pneumothorax have an increase in the alveolararterial

oxygen gradient. Although hypercapnia is rare with a primary spontaneous pneumothorax, it canbecome quite severe in the setting of a secondary spontaneous pneumothorax.

The electrocardiogram is not helpful for diagnosis. Nonspecific changes, including T-wave

inversion in the precordial leads, decreased amplitude of the R wave, and left axis deviation, areoften noted.


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The diagnosis of a spontaneous pneumomediastinum is often overlooked and requires a thorough

examination and a high index of suspicion. On physical examination, auscultation of the heart

may reveal a crunching sound during systole (Hamman sign) (6). Rarely, subcutaneous air maybe present. On CXR, a very thin lucent stripe can be seen outlining the heart and mediastinum. A

lateral neck radiograph may reveal subcutaneous air. The electrocardiogram is useful only in

helping to rule out ischemia in the patient who presents with substernal chest pain.EMERGENCY DEPARTMENT MANAGEMENT AND DISPOSITIONMost patients with primary spontaneous pneumothorax do not have significant respiratory or

cardiac compromise. Any hemodynamic instability should suggest the presence of tension

pneumothorax requiring immediate needle decompression followed by tube thoracostomy.Prospective studies evaluating management of spontaneous pneumothorax have significant

limitations. In 2001, the American College of Chest Physicians produced a Consensus Statement

regarding the management of spontaneous pneumothoraces. This consensus was reached by

combining evidence from these studies as well as a consensus of expert opinion. The followingrepresents their treatment recommendations (1).

Clinically stable patients with a small (


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A pneumothorax that occurs in the setting of chest wall trauma should be treated with a tube

thoracostomy to drain a possible coexisting hemothorax. These patients require admission to the

hospital and close monitoring.Management of pneumomediastinum is conservative. It is essential, however, to exclude

potentially catastrophic causes such as Boerhaave syndrome (esophageal rupture), which is

associated with a high mortality. A contrast mediumenhanced esophagram is usuallyrecommended in all patients who are at risk for esophageal rupture (post vomiting) withspontaneous pneumomediastinum (22). Patients with spontaneous pneumomediastinum and a

negative contrast mediumenhanced esophagram may be discharged as long as they are highly

reliable and have close outpatient followup arranged. Antibiotics are unnecessary if theesophagram is normal.

CRITICAL INTERVENTIONS

Perform immediate needle decompression on patients with suspected tensionpneumothorax

Insert chest tube for patients with large pneumothorax (>20%)

Perform an esophagram on patients with pneumomediastinum and suspected esophagealrupture

COMMON PITFALLS

Spontaneous pneumothorax and spontaneous pneumomediastinum are diagnoses ofexclusion. It is essential to consider other causes, including trauma, underlying

pulmonary disease, infection, and malignancy

Management of spontaneous pneumothorax by observation alone can save hospitalizationand health care costs only if used in the appropriate circumstances and only if the patientis compliant with treatment and receives appropriate discharge instructions

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spontaneous pneumothorax and pneumomediastinum

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