Air bronchogram
Updates to Article Attributes
Air bronchogram refers to the phenomenonvisibility of intraluminal bronchial air-filled bronchi (dark) being made visible by the opacificationagainst a background of surroundingopacified lung parenchyma (grey/white). Parenchymal opacificationExpulsion of gas from the parenchyma is partial or complete and can be due to absorption of gas (atelectasis) and/or replacement of gas by fluid, inflammatory cells, blood or tumour. The persistent presencepersistence of gas in the bronchi implies patency of proximal airways 6.
Air bronchograms can be seen with several processes:
pulmonary oedema: especially with alveolar oedema 3
non-obstructive atelectasis
severe interstitial lung disease
neoplasms: bronchioloalveolar carcinoma; pulmonary lymphoma
normal expiration
Air bronchograms that persist for weeks despite appropriate antimicrobial therapy should raise the suspicion of a neoplastic process. CT and guided biopsy may be plannedhelpful in such cases.
Radiographic features
Ultrasound
Sonographic air bronchograms arise as a secondary consequence of an extreme perturbation of the air-fluid relationship in the lung parenchyma, in which fluid-filled alveoli act as an excellent acoustic medium and allow visualisation of the lung parenchyma. Arborising tubular structures representing the bronchial tree may be visualised which, when patent, appear to contain punctiform-to-linear foci. These structures may remain fixed in position throughout the respiratory cycle or be observed to propagate distally and proximally with inspiration and expiration, respectively. This distinction is important for determining the aetiology of the underlying pathology 4:
-
dynamic air bronchograms move centrifugally with respiration
represent fluid mixed with air inside larger bronchi, which are in continuity with the gas inspired by the patient
indicates a non-retractile consolidation, ruling out resorption atelectasis
the specificity of 94% and a positive predictive value of 97% for pneumonia as the cause of the consolidation
-
static air bronchograms lack detectable movement
indicate isolated, trapped air, consistent with resorptive atelectasis
CT
Alveolar filling with fluid or cells contrasts with gas in the airways resulting in an air bronchgram.
Consolidation may be acute, or chronic and progressive depending on the cause. Pneumonia is typically acute, resolving within six weeks, however failure to resolve may indicate chronic progressive disease such as adenocarcinoma or lymphoma.
History and etymology
The term air bronchogram was coined by Ben Felson (1913-1988) 5.
See also
-<p><strong>Air bronchogram</strong> refers to the phenomenon of air-filled bronchi (dark) being made visible by the opacification of surrounding parenchyma (grey/white). Parenchymal opacification is partial or complete and can be due to absorption of gas (atelectasis) and/or replacement of gas by fluid, inflammatory cells or tumour. The persistent presence of gas in the bronchi implies patency of proximal airways <sup>6</sup>.</p><p>Air bronchograms can be seen with several processes:</p><ul>- +<p><strong>Air bronchogram</strong> refers to the visibility of intraluminal bronchial air (dark) against a background of opacified lung parenchyma (grey/white). Expulsion of gas from the parenchyma is partial or complete and can be due to absorption (atelectasis) and/or replacement by fluid, inflammatory cells, blood or tumour. The persistence of gas in the bronchi implies patency of proximal airways <sup>6</sup>.</p><p>Air bronchograms can be seen with several processes:</p><ul>
-</ul><p>Air bronchograms that persist for weeks despite appropriate antimicrobial therapy should raise the suspicion of a neoplastic process. CT may be planned in such cases.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>Sonographic air bronchograms arise as a secondary consequence of an extreme perturbation of the air-fluid relationship in the lung parenchyma, in which fluid-filled alveoli act as an excellent acoustic medium and allow visualisation of the lung parenchyma. Arborising tubular structures representing the bronchial tree may be visualised which, when patent, appear to contain punctiform-to-linear foci. These structures may remain fixed in position throughout the respiratory cycle or be observed to propagate distally and proximally with inspiration and expiration, respectively. This distinction is important for determining the aetiology of the underlying pathology <sup>4</sup>:</p><ul>- +</ul><p>Air bronchograms that persist for weeks despite appropriate antimicrobial therapy should raise the suspicion of a neoplastic process. CT and guided biopsy may be helpful in such cases.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>Sonographic air bronchograms arise as a secondary consequence of an extreme perturbation of the air-fluid relationship in the lung parenchyma, in which fluid-filled alveoli act as an excellent acoustic medium and allow visualisation of the lung parenchyma. Arborising tubular structures representing the bronchial tree may be visualised which, when patent, appear to contain punctiform-to-linear foci. These structures may remain fixed in position throughout the respiratory cycle or be observed to propagate distally and proximally with inspiration and expiration, respectively. This distinction is important for determining the aetiology of the underlying pathology <sup>4</sup>:</p><ul>
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