Page 183 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 13
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Surgery of the intrathoracic

trachea and mainstem bronchi

Carolyn Burton and Eric Monnet

Surgical diseases of the intrathoracic trachea are uncom- traffic accidents, although falling from a height is known
mon in both dogs and cats. This low prevalence of surgical to have caused the same injury in some. The traumatic inci-
disease, coupled with the anatomical location of this part dent stretches the trachea and leads to a partial circum-
of the trachea, means that surgical intervention, when ferential tear, or complete avulsion, of the intra thoracic
required, is best performed by a trained surgical specialist. trachea at a predictable site between 1 and 4 cm cranial to
Step-by-step technical detail of surgically managed condi- the tracheal bifurcation. Following avulsion, an airway lumen
tions of these structures is therefore outside the scope of is maintained by the intact peritracheal adventitial tissue
this manual. However, the authors hope that the following or by thickening of mediastinal tissue, creating a ‘pseudo-
descriptions will improve the recognition and diag nosis trachea’ or ‘pseudoairway’ that allows continued respira-
of several conditions of the intrathoracic trachea and tion. The ends of the avulsed trachea gradually become
enhance understanding of the treatment options available stenotic as granulation tissue develops in an attempt to
at specialist centres. repair the damage. Clinical signs may, therefore, take days
For general guidelines on tracheal anatomy and to weeks to develop.
surgical principles, please refer to Chapter 8.
Clinical signs
Intrathoracic tracheal and Cats with tracheal avulsion injuries present in two distinct
groups:
bronchial trauma
• Those showing acute-onset dyspnoea immediately
As the trachea is protected by the thoracic wall, trauma after the episode of trauma
to the thoracic trachea is uncommon in dogs and cats. • Those showing worsening dyspnoea days or weeks
Unlike the cervical trachea, penetrating or lacerating after the incident.
wounds are very rare. Perhaps the most common form of
intrathoracic tracheal trauma is rupture of the trachea. Cats that are presented acutely post trauma have radio -
Even these injuries are relatively rare, but over recent years graphic signs of pneumomediastinum and discontinuity of
they have become better recognized and more frequently the tracheal walls (see below), along with other evidence
diagnosed. Tracheal ruptures fall into two main categories: of traumatic disease. Such animals must undergo full eval-
uation and stabilization prior to definitive treatment of the
• Tracheal avulsion injury following blunt trauma to the tracheal injury. Cats presented days to weeks after trauma,
neck or thorax with dyspnoea, rarely have persisting concurrent injuries. It
• Iatrogenic tracheal rupture as a result of overinflation of is important to realize that screening thoracic radiographs
an endotracheal tube cuff. taken at the time of the initial trauma can alert the clinician
to the possibility of this injury, although it is possible for
Both of these forms of tracheal injury are more com- thoracic radiographs to appear remarkably normal in some
mon in the cat than in the dog. cases. Prompt radiographic diagnosis allows treatment to
be planned and undertaken before the severe dyspnoea
associated with attempted healing develops. This consid-
Intrathoracic tracheal avulsion injury erably reduces the risk to these patients.
There are many reports of feline tracheal avulsion injury in
the veterinary literature. Such publications have improved Diagnosis
the frequency of recognition of this condition and this has
led to much more frequent diagnosis. Thoracic radiography is the most useful tool for diagnosing
acute and chronic tracheal avulsion. In acute post-trauma
patients, pneumomediastinum, pneumothorax and discon-
Aetiology tinuity of the trachea can usually be appreciated (Figure
The condition is thought to be the result of a blunt traumatic 13.1). In addition, other radiographic signs of trauma
incident to the neck or thorax that involves hyper extension (fractured ribs, pulmonary alveolar infiltrate, long bone
of the neck. Most affected cats have been involved in road fracture) may be present. In most chronically affected

174 BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, second edition. Edited by Daniel J. Brockman, David E. Holt and Gert ter Haar. ©BSAVA 2018

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