Nena Tucker Pneumothorax is defined as the presence of air in the pleural space leading to a loss of negative intrathoracic pressure.1 Processes leading to a pneumothorax may be spontaneous, traumatic, or iatrogenic. A spontaneous pneumothorax occurs in the absence of thoracic trauma and can be categorized into primary or secondary. A primary spontaneous pneumothorax (PSP) develops in the otherwise healthy patient without underlying lung disease or trauma.2 A secondary spontaneous pneumothorax occurs in the presence of underlying lung disease but in the absence of trauma. A traumatic pneumothorax may result from penetrating or blunt force trauma to the chest wall.3 An iatrogenic pneumothorax occurs secondary to a medical procedure such as a pleural biopsy, central venous line placement, or positive-pressure mechanical ventilation.2 Any pneumothorax, regardless of type, may evolve into a tension pneumothorax in which there is increasing positive pressure in the pleural space caused by air being able to enter but not escape. PSP occurs most frequently in young adults aged 20 to 30.2 Additional risk factors include smoking, cannabis smoking, male gender, underlying lung disease, tall stature, and thin body habitus.1,4 There is also evidence to suggest that pregnancy and family history may also be risk factors. There is notable variance in the occurrence of primary pneumothorax between genders. This is evidenced by an incidence in men of 7.4 to 18 per 100,000 per year in the United States compared with 1.2 to 6 per 100,000 women per year in the United States.2 A pneumothorax can be potentially life-threatening. Astute assessment skills and prompt intervention are essential in the diagnosis and management of pneumothorax. The exact pathophysiology of PSP is unknown but is thought to be associated with subclinical or undiagnosed lung disease. The most common cause of PSP is spontaneous rupture of pleural apical blebs, lying in or just under the visceral pleura.5 The cause of these blebs in otherwise healthy individuals is unclear, although smoking has been shown to play a clear role by increasing the lifetime risk for development of a pneumothorax.4 A secondary pneumothorax can result from underlying pulmonary diseases such as chronic obstructive pulmonary disease, tuberculosis, lung cancer, asthma, endometriosis, and cystic fibrosis.4,5 Both penetrating and blunt force trauma can cause a traumatic pneumothorax irrespective of age, sex, or underlying lung disease. An iatrogenic pneumothorax is the complication resulting from a medical procedure, including invasive procedures such as the insertion of central lines and barotrauma related to surgery or mechanical ventilation.2 There does not appear to be any relationship between physical activity and pneumothorax; most episodes of PSP occur at rest. Although many distinct factors may contribute to a pneumothorax, it is the loss of negative pressure when air enters the pleural space that causes the lung or a portion of it to collapse. The clinical history and physical examination findings associated with a pneumothorax vary and are primarily dependent on the size of the pneumothorax (volume of air in the pleural space).6 The pertinent history would include history of previous pneumothorax, trauma, or smoking; current medications; allergies; history of strenuous exercise; recent medical procedures and other medical conditions. Although some patients with pneumothorax may be asymptomatic, the most common complaints are an acute onset of breathlessness and unilateral pleuritic chest pain.4,6 In general, the symptoms associated with a secondary pneumothorax are more severe than those associated with a primary pneumothorax. The physical findings reflect the size and nature of the pneumothorax. A tension or large pneumothorax is a medical emergency. Acute respiratory distress, diaphoresis, tachycardia, hypoxemia, tachypnea, tracheal deviation, and cyanosis are unmistakable and associated with a large or tension pneumothorax.4,6 A smaller pneumothorax may cause mild dyspnea and chest discomfort, or the patient may be asymptomatic. The diagnosis of pneumothorax has historically been established by plain chest radiography, including upright posteroanterior (PA), anteroposterior (AP), and/or lateral views,3 and portable chest radiography remains part of the standard workup for a suspected traumatic pneumothorax. However, chest radiography alone is inadequate for detection of pneumothoraces; sensitivities approximate 50%.7 Ultrasound has emerged as a reliable method of detecting pneumothorax. Lung sonography is especially useful in detecting small occult pneumothoraces and traumatic pneumothoraces. A computed tomography (CT) scan is the gold standard for the identification of pneumothorax because of its ability to differentiate between a pneumothorax and underlying bullous lung disease, such as complex cystic lung disease, or when accurate size measurements are required. Chest CT is not widely used owing to delayed diagnosis and risk for hemodynamic compromise associated with transportation out of the clinical area. Pulse oximetry and arterial blood gases (ABGs) can be used to determine level of hypoxia.
Pneumothorax
Definition and Epidemiology
Pathophysiology
Immediate emergency department referral or physician consultation is indicated for patients with respiratory compromise. Tension pneumothorax is a medical emergency requiring immediate intervention. The diagnosis is clinical and should not await radiologic confirmation.2
Clinical Presentation
Physical Examination
Diagnostics
Pneumothorax
Chapter 112
