Reading chest radiographs in the critically ill (Part II): Radiography of lung pathologies common in the ICU patient

Abstract

This is part II of two series review of reading chest radiographs in the critically ill. Conventional chest radiography remains the cornerstone of day to day management of the critically ill occasionally supplemented by computed tomography or ultrasound for specific indications. In this second review we discuss radiographic findings of cardiopulmonary disorders common in the intensive care patient and suggest guidelines for interpretation based not only on imaging but also on the pathophysiology and clinical grounds.

Keywords: Chest x-ray; cardiopulmonary disorders; intensive care unit.

Figure 1

Frontal chest radiograph (right) showing features of interstitial pulmonary edema. Radiographic signs (shown in the figure) that suggest interstitial pulmonary edema include loss of definition of large pulmonary vessels, the appearances of septal lines, interlobar septal thickening and diffuse reticular pattern associated with cardiomegaly. Both Kerley's A and Kerley's B lines are seen. The magnified view of the left costophrenic angle is from another patient, depicting Kerley's B lines (left)

Figure 2

Frontal chest radiograph showing features of alveolar pulmonary edema. The findings include opacification of both lungs with increasing density towards the lung bases due to a combination of air space shadowing and pleural effusions, cardiomegaly, upper lobe blood diversion (unreliable on supine AP radiograph) and an air bronchogram in the right upper zone

Figure 3

A frontal chest radiograph and axial CT show features of ‘batwing’ alveolar pulmonary edema. Chest radiographic findings include bilateral opacities that extend in a fan shape outward from the hilum in a batwing; pattern. With worsening alveolar edema, the lung opacification becomes increasingly homogenous

Figure 4

Supine portable chest radiograph showing extensive air space shadowing throughout the whole of the right lung and the left lung base due to alveolar pulmonary edema with associated pleural effusions secondary to heart failure. Note the air bronchograms in the right upper zone, sometimes seen with congestive heart failure

Figure 5

A frontal chest radiograph showing a unilateral edema

Figure 6

A patient's AP chest radiograph showing worsening of the air space shadowing with a further complication of a right-sided pneumothorax

Figure 7

AP radiograph of the same patient with ARDS as in Figure 6 with further complication of bilateral pneumothoraces secondary to pleural drain placement

Figure 8

Figures 8, 9 and 10 show a series of chest x-rays and CT scans over a period of 18 hours of a patient following blunt thoracic trauma. The initial chest x-ray [Figure 8] appears normal

Figure 9

Same patient as in Figure 8; changes develop rapidly initially as mild opacification at the right lung base followed by lung parenchymal infiltrate associated with a small pleural effusion

Figure 10

Same patient as in Figure 8; the opacity is in the peripheral lung, near the injured chest wall. The lesion rapidly progresses to cavitation as seen on the axial CT scans. The appearances are those of a lung contusion. Contusion however usually occurs earlier, is usually localized to the area affected by injury (e.g., unilateral and lower or upper zones) and improves over 48-72 hours. ARDS tends to be more generalized, is later in onset and slower to resolve

Figure 11

Plate atelectasis/discoid atelectasis (arrow) is common following thoraco-abdominal surgery and administration of a general anesthetic

Figure 12

The right upper lobe collapses into a triangular opacity with the lesser fissure migrating toward the anterior, superior and medial portions of the chest, closing like a Chinese fan. On an AP chest radiograph, the most striking feature is a superior and medial displacement of the minor fissure. Note also the raised right hemidiaphragm. On the lateral radiograph (not shown), the major fissure moves anteriorly, while the superior movement of the minor fissure is also seen. This atelectasis was secondary to a mucusplug

Figure 13

A frontal radiograph shows a segmental collapse of the right upper lobe. Note the elevation of the lesser fissure and the right hilum and a minor mediastinal shift to the right. This was an asthmatic patient, with a mucus plug

Figure 14

Right–middle-lobe atelectasis may cause minimal changes on an AP supine chest radiograph. Note the loss of definition of the right heart border. A collapsed right middle lobe is more clearly defined on lateral radiograph, which is not commonly available in the ICU patient. Attention to the fissures reveals that the horizontal and lower portions of the major fissures move towards each other resulting in a wedge of opacity pointing to the hilum. This is a middle-lobe consolidation mimicking middle-lobe atelectasis

Figure 15

An AP chest radiograph showing atelectasis of the right lower lobe. Note that the collapsing lobe has moved centrally and inferiorly towards the lower dorsal spine, where it is seen as a triangular opacity partially silhouetting the right hemidiaphragm and associated with a subtle air bronchogram. The minor fissure shows inferior displacement. Right–lower-lobe atelectasis can be differentiated from right–middle-lobe atelectasis by the persistence of the right heart border as in this case

Figure 16

The left lower lobe collapses medially and posteriorly to lie behind the heart. It classically displays a triangular opacity, which may be visible through the cardiac shadow or may overlie it, giving the heart an unusually straight lateral border. Silhouetting of the left hemidiaphragm usually occurs, which may be associated with an air bronchogram. It is also easily missed, especially on an underpenetrated film, where no detail is seen behind the heart

Figure 17

A frontal chest radiograph showing a left–upper-lobe atelectasis. The radiograph reveals hazy opacification of the left hilum, elevation of the left hilum, near-horizontal course of the left main bronchus, posterior leftward rotation of the heart and the Luftsichel or air crescent sign, the name given to the appearance of aerated lung abutting the arch of the aorta, between the mediastinum and the collapsed left upper lobe. An appearance on a lateral radiograph, if available, of the ICU patient may show retrosternal opacity and displacement of the greater fissure anteriorly

Figure 18

A chest radiograph (right) showing consolidation of left upper zone associated with an air bronchogram secondary to hospital-acquired pneumonia. The left image is an axial CT scan depicting an air bronchogram with bilateral pneumonic consolidation in another patient

Figure 19

An AP supine radiograph on an intubated patient showing patchy consolidation in both lung fields, more prominent on the left due to hospital-acquired pneumonia

Figure 20

An AP chest radiograph of a patient with tracheostomy showing development of aspiration pneumonia at the right lung base

Figure 21

A series of AP radiographs on the same patient as in Figure 20 showing evolution of aspiration pneumonia at the right lung basewithin

Figure 22

A frontal chest radiograph of a patient presenting with shortness of breath and hypoxemia, which shows no significant abnormality. However, CTPA (coronal reconstruction) shows extensive pulmonary embolism

Figure 23

A relatively late sign of pulmonary infarction is a rounded pleural based consolidation that is rounded centrally and is called a Hamptom's Hump. A Hamptom,s Hump can be differentiated from a pneumonic consolidation as the former lacks an air bronchogram. Note also a small right costophrenic effusion tracking up into the lesser fissure

Figure 24

A pleural-based segmental opacity due to infarction (left), subsequently converting into a thick-walled cavity (right)