Page 184 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 13 · Surgery of the intrathoracic trachea and mainstem bronchi

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Tracheal avulsion: lateral thoracic radiograph of a cat taken on
13.1 the day that it was hit by a car. The separated ends of the
trachea are seen (arrowheads) along with a pseudotracheal membrane Tracheal avulsion: view of the bulging pseudotracheal
(black arrows) and evidence of leakage of air: subcutaneous emphysema 13.3 membrane (black arrows) through a right third intercostal
(white arrows), pneumomediastinum and mild pneumothorax. thoracotomy. The cranial vena cava is seen ventral to the trachea (white
arrow).
animals, plain lateral thoracic radiographs show a well
defined spherical dilatation of the trachea at the level of the thoracotomy, allowing maintenance of the airway
the tracheal avulsion, with stenotic ends to the separated during the tracheal anastomosis (Figure 13.4a). Identi-
trachea (Figure 13.2). This avulsion is usually sited at the fication of the opening into the distal tracheal segment is
level of the second, third or fourth thoracic vertebra. not always easy, particularly in chronic cases, where it
Tracheoscopy can be used to confirm the diagnosis, if can be extremely small. There is often a considerable gap
necessary, and allows direct visualization of either circum- between the proximal and distal tracheal segments due
ferential tracheal ring disruption or tracheal stenosis. In to retraction as a result of the avulsion. Identification of
animals with longstanding disease where the scarred ends the transected proximal segment can be improved with
of the trachea are cicatrized, stenosis will prevent the advancement of the orotracheal tube. Any damaged
passage of the endoscope onwards into the pseudo- tracheal rings are then resected. Tracheal anastomosis is
trachea and particularly into the distal tracheal segment. carried out, preplacing all sutures prior to tying (Figure
Tracheoscopy is not without risk in these patients. 13.4b). Ventilation is resumed via a long orotracheal tube,
which is advanced past the anastomotic site into the
distal tracheal segment.
The surgical and anaesthetic management during
correction of intrathoracic tracheal avulsion injuries is
tech nically demanding, and referral is advised. However,
with specialist input the success rate and long-term prog-
nosis are extremely good following surgical correction.

PRACTICAL TIP
Tracheal stenosis can make positive pressure
ventilation difficult in these cats. Prior to opening the
thorax, these patients may do better if left to breathe
spontaneously. Forceful positive pressure ventilation
can lead to rupture of the pseudotracheal membrane
and life-threatening tension pneumothorax. Once the
thoracic cavity is open, spontaneous breathing efforts
will be fruitless; the surgeon must therefore be
prepared to secure an airway rapidly if positive
Tracheal avulsion: lateral thoracic radiograph of a cat taken pressure ventilation also proves ineffective. To prevent
13.2 3 weeks after it was hit by a car. The stenotic ends of the contamination of the operating theatre environment
separated trachea can be seen (white arrows) and the pseudotracheal with anaesthetic gases total intravenous anaesthesia
membrane is obvious (black arrows). (TIVA) is recommended

Surgical correction
Left principal bronchus avulsion/rupture
Surgical correction requires a right third or fourth inter costal
space thoracotomy or, occasionally, a cranial sternotomy, A similar injury to intrathoracic tracheal avulsion has
allowing access to the pseudotrachea. The pseudotrachea also been reported, involving the left principal bronchus
has a typical appearance (Figure 13.3). in two cats (White and Oakley, 2000). The aetiology in
The pseudotrachea is opened and a sterile endo- these cases was also thought to be traumatic; the clinical
tracheal tube passed into the distal tracheal segment via signs were tachypnoea and increased respiratory effort.

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