Thoracic abnormal air collections in patients in the intensive care unit: radiograph findings correlated with CT

Abstract

An abnormal collection of air in the thorax is one of the most common life-threatening events that occurs in the intensive care unit. Patient management differs depending on the location of the air collection; therefore, detecting abnormal air collection and identifying its exact location on supine chest radiographs is essential for early treatment and positive patient outcomes. Thoracic abnormal air collects in multiple thoracic spaces, including the pleural cavity, chest wall, mediastinum, pericardium, and lung. Pneumothorax in the supine position shows different radiographic findings depending on the location. Many conditions, such as skin folds, interlobar fissure, bullae in the apices, and air collection in the intrathoracic extrapleural space, mimic pneumothorax on radiographs. Additionally, pneumopericardium may resemble pneumomediastinum and needs to be differentiated. Further, some conditions such as inferior pulmonary ligament air collection versus a pneumatocele or pneumothorax in the posteromedial space require a differential diagnosis based on radiographs. Computed tomography (CT) is required to localize the air and delineate potential etiologies when a diagnosis by radiography is difficult. The purposes of this article are to review the anatomy of the potential spaces in the chest where abnormal air can collect, explain characteristic radiographic findings of the abnormal air collection in supine patients with illustrations and correlated CT images, and describe the distinguishing features of conditions that require a differential diagnosis. Since management differs based on the location of the air collection, radiologists should try to accurately detect and identify the location of air collection on supine radiographs.

Consensus statement on thoracic radiology terminology in Portuguese used in Brazil and in Portugal

“…No caso do pneumotórax iatrogênico, esse frequentemente resulta de procedimentos torácicos como biopsia pulmonar, inserção de cateter venoso central ou cirurgia torácica. (75)…”

Spontanes Pneumomediastinum (Hamman-Syndrom) mit Pneumorrhachis als seltene Ursache für akuten Thoraxschmerz bei einem jungen Patienten mit akut exazerbiertem Asthma bronchiale

“…Das "tubular artery sign" beschreibt, dass beide Seiten der Gefäße hervortreten und diese daher als tubuläre Strukturen erscheinen [13]. Sind die Bronchialwände von Luft umgeben und im Inneren der Bronchi ebenfalls Luft nachweisbar, entsteht das "double bronchial wall sign" [13]. In manchen Fällen kann das "continuous diaphragm sign" sichtbar sein, bei dem die Luft im Mediastinum das Perikard von der Zwerchfelloberfläche trennt und so das Zwerchfell in der p. a.-Thoraxaufnahme als durchgängige Struktur erscheint [14].…”

Abnormal Free Gas Collection in Radiography: A Pictorial Review

“…Pneumothorax is caused by the rupture of bullae, trauma, and iatrogenic complication after an intervention, such as thoracentesis and positive pressure ventilation. (2) If it is not caused by trauma, it is referred to as spontaneous; this may be primary (not associated with an underlying cause) or secondary to preexisting significant pulmonary disease. (3) The sudden entry of air into the pleural space causes the negative pressure to rise higher than the intra-alveolar pressure,collapsing the lung.…”

“…Tension pneumothorax is alife-threatening medical emergency situation. (2,4,5) Radiographic findings of tension pneumothorax are the same as a simple pneumothorax with the addition of mediastinal displacement, flattening of the heart border, diaphragmatic inversion, increased intercostal space, and total or subcostal lung collapse, reflecting the expansion of the affected hemithorax (Figure 2). ( 4))…”