|Results 1-1||<< Back|
Mentions: Pleural effusions are accumulations of fluid within the pleural space [Figures 35–41]. Pleural effusions occur frequently in the ICU patients, which may be secondary to heart failure, fluid overload, hypoproteinemia, infection, pulmonary embolism, thoracic and upper abdominal surgery, neoplastic disease, subphrenic inflammatory processes, trauma and ascites. The fluid could be blood, chyme, pus, transudates or exudates. The radiographic appearance of a pleural effusion is dependent on the position of the patient. Pleural fluid accumulates in the dependent areas of the chest. A pleural effusion is easier to identify in the erect patient as fluid collects at the base of the lung, causing costophrenic angle blunting and decreased visibility of the lower lobe vessels. In the supine position, identification of a pleural effusion is more challenging. In the supine position, pleural fluid accumulates in the posterior basilar space, which appears as homogenous density that increases in intensity towards the lung base. The normal bronchovascular markings are retained in this veil-like density. With increasing amount of pleural fluid, the diaphragm loses its contour and costophrenic angle may be obliterated. However, it should be remembered that the pleural space may accommodate up to a liter of fluid above the diaphragm without blunting of the costophrenic angle. With larger pleural effusions, the fluid may appear as pleural cap at the lung apex, making it easier to identify on a supine radiograph. The fluid may sometimes accumulate on the medial side of the lung, appearing as a widened mediastinum. Often, smaller pleural effusions are missed on supine chest radiographs despite meticulous technique. When effusions are not readily apparent on a supine chest radiograph but clinically suspected, a lateral decubitus film is indicated. The film should be taken with the side of the patient suspected to have an effusion in the dependent position. The lateral decubitus film would not only confirm smaller pleural effusions but can also differentiate between loculated and free effusions. The latter information is important when pleural drainage is planned, as loculated effusions may need more than one drain. A pleural effusion at the lung base is termed a subpulmonic effusion and is a common occurrence in the ICU patient. On the chest radiograph, a subpulmonic pleural effusion appears as a raised hemidiaphragm with flattening and lateral displacement of the dome. A lateral decubitus film can usually resolve this.
Reading chest radiographs in the critically ill (Part I): Normal chest radiographic appearance, instrumentation and complications from instrumentation
Affiliation: Department of Medicine and Medical Imaging, King Saud University for Health Science, King Abdulaziz Medical City, King Fahad National Guard Hospital, Riyadh, Saudi Arabia. email@example.com