Atelectasis

What does atelectasis mean? Lung collapse with loss of internal air Atelectasis can affect: –a subunit of a lobe (subsegmental) –a lobe –or a whole lung Subsegmental atelectasis is most common

Causes of Lobar/Whole Lung Atelectasis Proximal stenosing bronchogenic carcinoma Asthma (mucus plugging) Inhaled foreign body Retention of secretions (e.g. postop) Endotracheal tube inserted too far

CXR Features of Lobar/Whole Lung Atelectasis Ipsilateral tracheal displacement Increased density of collapsed lung tissue Ipsilateral mediastinal shift Elevation of the hemidiaphragm Herniation of the opposite lung across the midline

Complete left lung collapse

Trachea deviated to left Heart shifted to left Opaque (white) hemithorax, caused by non- aerated lung

Patterns of Lobar Collapse The left lung has 2 lobes (upper, lower), and the right lung 3 lobes (upper, middle, and lower) The collapse of each lobe has specific appearances on a CXR Examples of each type of lobar collapse now follow A revision of your lung anatomy now might be helpful

Surface markings of the lobes The lingula is part of the left upper lobe Note that the lower lobes extend quite high – above the level of the carina

Right Upper Lobe Collapse

Examples of Lobar Atelectasis There now follows examples of each type of lobar atelectasis. Some are difficult to recognise! For each one, look for volume loss (e.g. ribs closer together), and movement of other structures to occupy the space created by the atelectasis.

Right Lower Lobe Collapse

The right lung has lost volume and the horizontal fissure is depressed (red arrow)

Middle Lobe Collapse

The right heart border is blurred. Middle lobe collapse can be very difficult to detect, and a lateral CXR can be helpful if in doubt (next slide)

Middle Lobe Collapse Note the wedge shape on the lateral CXR. The horizontal fissure (arrow) is depressed

Left Upper Lobe Collapse

R

Note loss of volume of the left hemithorax and generalised increased density. The lung markings still visible are those of the lower lobe, which expands to fill the space left by the collapsed upper lobe R Left Upper Lobe Collapse

Left Lower Lobe Collapse

Note loss of left diaphragm contour medially, volume loss of the left hemithorax and the retrocardiac straight line (representing the collapsed lower lobe)

Take Home Points The commonest cause of lobar / total lung collapse in adults is lung cancer All patients with lobar or total lung collapse need further assessment to determine the underlying cause The CXR appearances of collapse vary according to where the collapse is