Bronchoscopy:
Bronchoscopy is an essential and useful tool to assess the airway and
identify the site and number of complete rings. This however needs to be
performed by a skilled operator as iatrogenic oedema of the tracheal
mucosa may completely obstruct an already narrow airway. Rigid endoscopy
can also be used, however views may be limited if there is significant
tracheal stenosis. Assessment of the airway via laryngeal mask is ideal
as it avoids instrumentation in the larynx.8,37,38Maintaining the airway and ensuring ventilation and oxygenation are
paramount tasks for the anaesthetist especially in critical
cases.38 In neonates and infants, typically a 2.8mm
flexible bronchoscope is used.37 If the obstruction is
severe, a 2.2 mm suction fiberoptic scope can pass through distal
tracheal stenosis to visualise the carina. Topical vasoconstrictor
epinephrine may reduce procedural risk.
Dynamic bronchoscopy may also be useful to differentiate fixed stenosis
from distal malacia , the latter occurring between 20 and 40% of cases.
Tracheobronchomalacia contribute significantly to long-term morbidity
and need for long-term ventilation, tracheostomy or highly specialised
intervention such as tracheal and bronchial
stents.36,39,40 The typical bronchoscopic features of
LPA sling are shown in figure 9 with mild cranial compression and left
bronchus origin narrowing posteriorly by the retro-tracheal LPA (Type
Ia) to significant carinal and right distal lateral tracheal wall
compression obscuring the view of the carina into the right main
bronchus. The severe end of the spectrum with multiple complete rings
and an absent trachealis muscle (figure 9c). These are best seen with a
well suctioned airway clear of secretions as these may obscure the
presence of complete rings along the trachea floor. If tracheal stenosis
is severe it may not even be possible to view the carina - in this
instance bronchograms are very informative.7