Bronchograms:
Bronchograms should be performed under fluoroscopy preferentially with
biplane imaging with AP and lateral views or with the recent 3D dynaCT
reconstructions. Bronchogram can accurately determine the exact calibre
of the smaller airways which may not be accessible by bronchoscopy.
Figure 8 demonstrates the accuracy of this technique in comparison to a
simultaneous CT that shows a left main bronchus artefact on CT only -
this may be misleading especially for surgical planning. If contrast
extends into the alveoli it may also give valuable information on lobar
and sub segmental bronchial supply. Whilst only a small volume (
typically 0.25 to 0.5ml/kg) of contrast agent are used (Omnipaque or
Visipaque) it is rapidly resolved and does not usually cause bronchial
irritation. Radiopaque per fluorocarbon is the ideal contrast agent as
this is inert and rapidly evaporates following intracheal
administration.41 Gentle balloon dilation to access
the tracheal calibre and if there is fixed stenosis can also be done
with a low pressure balloon (figure 9) or to assess the airway for
potential stenting. Bronchogram and balloon dilations form the
cornerstone of post-operative care to treat recurrent stenosis at the
operative site.
A single static bedside AP bronchogram in an intubated patient can be
invaluable to rapidly diagnose long segment tracheal stenosis and the
extent of tracheobronchial involvement (figure 11). Here, a standard
chest X-ray is performed with 0.25 to 0.5ml/kg of contrast agent via a
thin 6 Fr feeding tube positioned at the end of the endotracheal tube.
The contrast is injected rapidly and an image is obtained 3 to 5 seconds
after intratracheal injection under expiration. Dense hold-up of
contrast indicates significant tracheal obstruction as normally the
contrast agent dissipates rapidly into the bronchi creating the typical
tram track appearance that lines the airway. This can be performed at
the bedside in intensive care if the patient is too unstable to move or
the stenosis is too small for even a bronchoscopy to assess. Barium
swallow is to delineate the oesophagus very limited diagnostic value.