Page 185 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery

dis connecting the anaesthetic delivery tube, shear forces
develop that further damage the trachea. Tracheal
VetBooks.ir result of using a stylet. The type of endotracheal tube cuff
rupture has also been caused during intubation as a
used in these procedures appears to have little influence
on whether a rupture is caused, with both high pressure-
low volume and low pressure-high volume cuffs reported
as causing a problem. The most common site of injury is
the dorsal wall of the trachea at the junction between the
ends of the tracheal rings and the tracheal membrane. In
some animals the tracheal injury results in 360-degree
pressure necrosis of the tracheal wall, secondary either
to cuff contact or to pressure from the tip of the endo-
tracheal tube.

(a) Clinical signs and management
Most cats are presented either immediately or within 1–6
days of injury because of subcutaneous emphysema.
Other reported clinical signs include dyspnoea, gagging,
regurgitation, pyrexia and cough. The diagnosis is
often presumptive, with a history of a recent anaesthetic
episode and subsequent development of subcutaneous
emphysema.
Cervical and thoracic radiography can be helpful; sub-
cutaneous emphysema, discontinuity or irregularity of the
tracheal gas shadow, pneumomediastinum and pneumo-
thorax are commonly identified abnormalities. If further
confirmation of the diagnosis is required, tracheoscopy
can be helpful; however, the tracheal mucosa and lumen
can appear remarkably normal on tracheoscopy despite
the presence of a large tear.
Careful examination of the tracheal mucosa, particu-
(b) larly around any areas of mild inflammation, is necessary
(a) The tracheal avulsion is exposed through a right lateral to identify a defect.
13.4 thoracotomy and a sterile endotracheal tube is used to secure Cats with mild to moderate clinical signs that resolve
the airway whilst the sutures are preplaced through the ends of the with cage rest can be successfully managed conserva-
trachea. (b) Preplaced sutures are tied following removal of the tively with rest, oxygen therapy and sedatives if required.
endotracheal tube. Patients need to be carefully monitored, and serial re-
evaluations of respiratory status and the amount of sub-
cutaneous emphysema are necessary during this time.
Diagnosis was achieved with thoracic radiography, bron-
The subcutaneous emphysema can take some time to
choscopy and computed tomography (CT). Radiographic resolve, usually within 2 weeks, but up to 6 weeks has
findings included a spherical enlargement of the base
been reported. Cats with severe dyspnoea or worsening
of the left mainstem bronchus, pneumomediastinum, clinical signs during conservative management require
pneumo thorax, pleural effusion and retraction of all lung
surgical repair. This may be achieved via a right lateral
lobes in the left hemithorax. Bron choscopy confirmed third or fourth intercostal space thoracotomy or ventral
almost complete stenosis of the left principal bronchus.
midline cervical approach combined with a median stern-
In both cases successful surgical correction was otomy, depending on the position and extent of the rup-
achieved via a right fifth intercostal thora cotomy, resec-
ture (Figure 13.5). Most ruptures occur at the junction of
tion of the damaged/stenosed segment and anastomosis the tracheal cartilage and dorsal tracheal membrane, and
of the bronchus.
gentle rotation of the trachea using stay sutures improves
visualization of the rupture site. Once again, careful
Iatrogenic tracheal rupture anaesthetic management is required and TIVA may be
necessary if secure endo tracheal intubation distal to the
Aetiology tear is not possible. The prognosis for these cats follow-
Tracheal injuries resulting from overinflation of an endo- ing resolution of clin ical signs with conservative manage-
tracheal tube cuff are more commonly seen within the ment or surgery is good.
cervical trachea than in the intrathoracic trachea. Such It is important to note that, to the authors’ knowledge,
injuries are more common in cats, although it is possible to there are no reports of tracheal rupture associated with
cause similar injuries in dogs (see Chapter 8). the use of non-cuffed endotracheal tubes. Prevention of
The injury typically occurs as a result of the use of a aspiration of fluids can be achieved by using a non-
cuffed endotracheal tube. Seventy percent of cats sus- cuffed tube together with packing of the pharyngeal area
taining this injury are undergoing anaesthesia for a dental with a surgical swab. If cuffed endotracheal tubes are
procedure. There is a tendency to overinflate the cuff used they should be inflated carefully with the minimum
during dental procedures to minimize the chance of aspir - volume of air needed to achieve a seal, the anaesthetic
ation of fluid into the patient’s airway. In addition, animals circuit should be disconnected each time the patient is
are repositioned frequently; if this is done without moved, and the cuff deflated prior to extubation.

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