Pleuritis – Top USMLE Diseases

Obstructive sleep apnea (OSA) is a common disorder in adults, characterized by recurrent obstruction of the upper airway during sleep, causing hypoxia and fragmented sleep.  OSA is due to a partial or complete collapse of the upper airway and is associated with snoring, restlessness, sleep interruption, fatigue, and daytime somnolence. Untreated OSA is associated with an increased risk of cardiovascular disease, hypertension, pulmonary arterial hypertension, and accidents related to hypersomnolence. The diagnosis relies on medical history, and polysomnography can confirm the diagnosis. Most cases remain undiagnosed. Management includes lifestyle changes, methods of positive airway pressure, and surgical intervention.

Diagnostic modalities such as chest X-rays provide static images of the thoracic cavity, including the lungs and airways. While providing a wealth of anatomical information necessary for the diagnosis of pulmonary disease, chest X-rays do not give much information about the individual's respiratory function. Pulmonary function tests are a group of diagnostic procedures yielding useful, quantifiable information about the rate of the flow of air through the individual's airways, lung capacity, and the efficiency of gas exchange in relation to time. The most commonly utilized tests include spirometry (before and after bronchodilator use), lung volumes, and quantitation of diffusing capacity for carbon monoxide (CO). The tests can be influenced by the individual's effort/fatigue, disease state, or anatomical malformation.

Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. To perform this function, the lungs need to be able to capture as much O2 as possible, a task that is easily achieved owing to their elastic morphology. Each lung is enclosed within the visceral pleura and completely fills 1 of the non-symmetrical pleural cavities, which are situated on the left and right sides of the mediastinum. The lungs encase the bronchial tree and are divided functionally and anatomically into lobes.

Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Imaging can confirm the presence of a pleural effusion, and pleural fluid analysis can help in the evaluation of an etiology. Management is dependent on the underlying condition and whether the effusion is causing respiratory distress. Drainage of the effusion may provide symptomatic relief.

A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Symptom severity depends on the degree of the collapsed lung. A large or tension pneumothorax can result in cardiopulmonary collapse. A diagnosis is made with imaging, though tension pneumothorax is a clinical diagnosis. Management is based on the size and stability of the patient, and can include needle decompression and chest tube (thoracostomy) placement.

Obstructive sleep apnea (OSA) is a disorder characterized by recurrent obstruction of the upper airway during sleep, causing hypoxia and fragmented sleep. Obstructive sleep apnea is due to a partial or complete collapse of the upper airway and is associated with snoring, restlessness, sleep interruption, and daytime somnolence. The diagnosis relies on medical history, and polysomnography can confirm the diagnosis. Management includes lifestyle changes, methods of positive airway pressure, and surgical intervention.