Pneumothorax, Iatrogenic, Spontaneous and Pneumomediastinum

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Author

Andrew K Chang, MD, Associate Professor, Department of Emergency Medicine, Albert Einstein College of Medicine, Montefiore Medical Center

Nothing to disclose.

Coauthor(s)

Pinaki Mukherji, MD, Assistant Professor, Attending Physician, Department of Emergency Medicine, Montefiore Medical Center

Nothing to disclose.

Specialty Editor(s)

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine

eMedicine Salary Employment

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center

Nothing to disclose.

Joseph A Salomone III, MD, Associate Professor and Attending Staff, Truman Medical Centers, University of Missouri-Kansas City School of Medicine; EMS Medical Director, Kansas City, Missouri

Nothing to disclose.

Paul Blackburn, DO, FACOEP, FACEP, Program Director, Department of Emergency Medicine, Maricopa Medical Center; Assistant Professor, Department of Surgery, University of Arizona

Nothing to disclose.

Chief Editor

Robert E O'Connor, MD, MPH, Professor and Chair, Department of Emergency Medicine, University of Virginia Health System

Nothing to disclose.

Background

Pneumothorax is air in the potential space between the visceral and parietal pleura of the lung. Air can enter the intrapleural space through a communication from the chest wall (ie, trauma) or through the lung parenchyma across the visceral pleura.

Pneumothoraces secondary to trauma are relatively straightforward and usually require tube thoracostomy. Spontaneous pneumothorax, however, is a commonly encountered problem with approaches to treatment that can vary from observation to aggressive intervention. This article focuses on differentiating primary spontaneous (no obvious underlying lung disease), secondary spontaneous (underlying lung disease), and iatrogenic pneumothoraces (which are traumatic but typically are smaller and more easily managed). In addition, pneumomediastinum (free air in the mediastinal structures) is discussed.

At one time, the term iatrogenic pneumothorax was predominantly the result of deliberate injection of air into the pleural space as a treatment of tuberculosis (TB). The terminology evolved to the preference for "induced" or "artificial" pneumothorax to indicate pulmonary TB treatment, before arriving at the classification below. Pulmonary TB remains a significant cause of secondary pneumothorax.

Classification

Primary spontaneous pneumothorax

Secondary spontaneous pneumothorax

Iatrogenic pneumothorax

Pneumomediastinum

Pathophysiology

Spontaneous pneumothoraces in most patients occur from the rupture of blebs and bullae. While primary pneumothorax is defined as a lack of underlying pulmonary disease, these patients have asymptomatic blebs and bullae detected on CT scans or upon thoracotomy. Until a bleb ruptures and causes a pneumothorax, no clinical signs or symptoms are present.

The pleural space has a negative pressure, with the chest wall tending to spring outward and the lung's elastic recoil tending to collapse. If the pleural space is invaded by gas from a ruptured bleb, the lung collapses until equilibrium is achieved or the rupture is sealed. As the pneumothorax enlarges, the lung becomes smaller.

The main physiologic consequence of this process is a decrease in vital capacity and partial pressure of oxygen. Young and otherwise healthy patients can tolerate these changes fairly well, with minimal changes in vital signs and symptoms, but those with underlying lung disease may have respiratory distress.

With pneumomediastinum, excessive intra-alveolar pressures lead to rupture of perivascular alveoli. Air escapes into the surrounding connective tissue and dissects into the mediastinum. Esophageal trauma or elevated pressures may also allow air to dissect into the mediastinum. Air may then travel superiorly into the visceral, retropharyngeal, and subcutaneous spaces of the neck. From the neck, the subcutaneous compartment is continuous throughout the body; thus, air can diffuse widely. Mediastinal air can also pass inferiorly into the retroperitoneum and other extraperitoneal compartments. If the mediastinal pressure rises abruptly or if decompression is not sufficient, the mediastinal parietal pleura may rupture and cause a pneumothorax (in 10-18% of patients).

Epidemiology

Frequency

United States

Incidence of primary spontaneous pneumothorax (age-adjusted) is 7.4-18 cases per 100,000 persons per year for men and 1.2-6 cases per 100,000 persons per year for women. Incidence of secondary spontaneous pneumothorax (age-adjusted) is 6.3 cases per 100,000 persons per year for men and 2 cases per 100,000 persons per year for women. Chronic obstructive pulmonary disease (COPD) is a common cause of secondary spontaneous pneumothorax that carries an incidence of 26 cases per 100,000 persons. It is likely that the incidence for spontaneous pneumothorax is underestimated. Up to 10% of patients may be asymptomatic, and others with mild symptoms may not present to a medical provider.

The incidence of iatrogenic pneumothorax is 5-7 per 10,000 hospital admissions, with thoracic surgery patients excluded as pneumothorax may be a typical outcome following these surgeries. Pneumomediastinum occurs in approximately 1 case per 10,000 hospital admissions.

Mortality/Morbidity

Sex

Age

History

Acute onset of chest pain, often pleuritic and associated with shortness of breath, is typical. Both of these symptoms occur in 64-85% of patients. Chest pain in primary spontaneous pneumothorax often improves over the first 24 hours, even without resolution of the underlying air accumulation. Well-tolerated primary pneumothorax can take 12 weeks to resolve. In secondary pneumothorax, chest pain is more likely to persist with more significant clinical symptoms.

Despite descriptions of Valsalva maneuvers and increased intrathoracic pressures as inciting factors, spontaneous pneumothorax usually develops at rest. This must be differentiated from pneumomediastinum (see below). Many affected individuals do not seek medical attention for days after symptoms develop. This trend is important, because the incidence of reexpansion pulmonary edema increases in patients whose chest tubes have been placed 3 or more days after the pneumothorax occurred.

Smoking increases the risk of a first spontaneous pneumothorax by more than 20-fold in men and by nearly 10-fold in women compared with risks in nonsmokers.[1] Increased risk of pneumothorax and recurrence appears to rise proportionally with number of cigarettes smoked.

The most common underlying abnormality in secondary spontaneous pneumothorax is COPD. Cystic fibrosis carries one of the highest associations, with more than 20% reporting spontaneous pneumothorax.

A history of previous pneumothorax is important, as recurrence is common, with rates reported between 15 and 40%. Up to 15% of recurrences can be on the contralateral side. Secondary pneumothoraces are often more likely to recur, with cystic fibrosis carrying the highest recurrence rates at 68-90%. No study has shown that the number or size of blebs and bullae found in the lung can be used to predict recurrence.

Pneumomediastinum usually occurs when intrathoracic pressures become elevated. This elevation may occur with an exacerbation of asthma, coughing, vomiting, childbirth, seizures, and a Valsalva maneuver. In many patients who present with pneumomediastinum, it occurs as a result of endoscopy and small esophageal perforation.

Symptoms of primary and secondary spontaneous pneumothorax, iatrogenic pneumothorax, and pneumomediastinum may include the following:

Physical

The general appearance of the patient may vary from asymptomatic to respiratory distress. Findings on lung auscultation also vary depending on the extent of the pneumothorax, but they may include diminished or absent breath sounds, or hyperresonance on percussion of the affected side. General clinical signs include the following:

Causes

Causes of pneumothorax and pneumomediastinum may include the following:

Imaging Studies

Procedures

Prehospital Care

Emergency Department Care

Immediate attention to the ABCs while assessing vital signs and oxygen saturation is paramount. ED care depends on the hemodynamic stability of the patient. All patients should receive supplemental oxygen to increase oxygen saturation and to enhance the reabsorption of free air. Treatments for primary and secondary spontaneous pneumothorax are the following:

Consultations

Physicians from various services may be needed to care for patients who require tube thoracostomy and admission. A surgeon and a pulmonologist should evaluate patients with recurrent disease to determine the cause and further management.

Medication Summary

The goals of pharmacologic therapy are to reduce symptoms and prevent potential complications.

Class Summary

Anesthetic agents are used for analgesia in the treatment of sclerotic lesions.

Lidocaine (Dilocaine)

Clinical Context:  Decreases the permeability to sodium ions in neuronal membranes, resulting in the inhibition of depolarization, and blocking the transmission of nerve impulses. The application of 5% gel is effective in the treatment of painful lesions.

Class Summary

These agents are useful for premedication prior to sclerosis and placement of a thoracostomy tube.

Lorazepam (Ativan)

Clinical Context:  Sedative hypnotic with short onset of effects and relatively long half-life. Increases the action of GABA, a major inhibitory neurotransmitter in the brain. May depress all levels of the CNS, including the limbic and reticular formations.

Class Summary

Pain control is essential to good patient care. It ensures patient comfort and promotes pulmonary toilet. Most analgesics have sedating properties, which are beneficial for patients with painful skin lesions. Analgesics are important in the initial placement of thoracostomy tubes and for controlling pain after the procedure.

Morphine (Duramorph, MS Contin, Oramorph)

Clinical Context:  DOC for analgesia because of reliable and predictable effects, safety profile, and ease of reversibility with naloxone.

Further Inpatient Care

Further Outpatient Care

Deterrence/Prevention

Complications

Prognosis

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This is a chest radiograph of an elderly male with chronic obstructive pulmonary disease who presented with a second left-sided spontaneous pneumothorax in 2 months. Chest thoracostomy was performed, the patient was admitted, and talc pleurodesis was performed the next day.

This chest radiograph shows pneumomediastinum (radiolucency noted around the left heart border) in this patient who had a respiratory and circulatory arrest in the ED after experiencing multiple episodes of vomiting and a rigid abdomen. The patient was taken immediately to the operating room, where a large rupture of the esophagus was repaired.