Page 122 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 8 · Surgery of the extrathoracic trachea

Technique separated on the midline. Dissection should avoid and
preserve the recurrent laryngeal nerves; the use of
Tracheal resection and anastomosis of the extrathoracic
VetBooks.ir trachea should be performed in a controlled manner, with of the resection are determined, the priority is to obtain
monopolar cautery should be avoided. Once the limits
good surgical access and careful airway management. The
access to the airway distally. This may be achieved by
procedure is technically demanding and requires careful
planning and teamwork but does not require any special- advancement of the orotracheal tube beyond the site of
resection or by direct intubation of the distal tracheal
ized equipment, although the use of sterile endotracheal
segment, when passage of the tube is not possible (Figure
tubes is required. The aims of surgery are to achieve 8.17). Sutures are placed as ‘stay sutures’ in the proximal
precise approximation and minimal tension at the anasto-
and distal trachea to aid manipulation. When distal
mosis site, to allow rapid healing with minimal risk of segment tracheal intubation is required, a tracheotomy
complications. Tension at the anastomosis site has an incision is performed at the distal extent of the resection
important influence upon the nature of the healing: the to allow insertion of a cuffed sterile endotracheal tube; a
degree of stenosis is increased when anastomosis tension range of sizes should be available (see Figure 8.16b). The
is high, due to gap formation and consequent second anaesthesia circuit is then detached from the oro tracheal
intention healing (Demetriou et al., 2006). tube and connected to the sterile endotracheal tube
The length of the segment of trachea to be resected is inserted via the tracheostomy. Sterile drapes may be used
determined by findings on diagnostic imaging, tracheos- to shroud the anaesthesia circuit, or sterile apparatus may
copy and assessment at surgery (Figure 8.16a). For mass be used. Following establishment of a reliable airway, the
lesions, cytological or histopathological samples will have proximal portion of trachea can be carefully dissected,
ideally been obtained prior to surgery to allow thorough avoiding damage to the delicate vasculature and the
surgical planning. The maximum number of rings that can recurrent laryngeal nerves. Once the section of trachea
be resected is variably reported: up to 50% of the tracheal has been resected, the proximal and distal trachea can
length (around 17–23 rings) has been documented in be brought into approximation; the sterile endotracheal
experimental dogs but this requires considerable use of tube is removed from the distal trachea and the oro-
dissection and tension-relieving techniques (Dallman and tracheal tube is advanced from the proximal to the distal
Bojrab, 1982). To minimize the risk of complications, trachea (see Figure 8.16c).
removal of no greater than 25% of the tracheal length The precise site of tracheal transection should be
(8–10 tracheal rings) in the adult dog is recommended (Lau selected carefully when the tracheal segment is resected,
et al., 1980). Given the fragility of the trachea in the imma- with tracheotomy performed either through (‘split-ring’)
ture dog, no more than 20% of the tracheal length can or between the tracheal cartilages. Tracheal anastomosis
be resected because the cartilage rings cannot withstand using the split-ring technique is reported to result in less
the necessary forces to support tension-relieving sutures stenosis than other techniques (Hedlund, 1984); however,
with longer resections (Maeda and Grillo, 1973). this may be challenging to perform in small animals. The
Prior to orotracheal intubation, an assessment of anastomosis is repaired using preplaced sutures of a
laryngeal function should be performed under a light monofilament absorbable material, such as polydioxanone
plane of anaesthesia. The extrathoracic trachea is (Fingland et al., 1995) (Figure 8.18). Sutures are placed
accessed via a ventral midline cervical approach; the dorsally in the dorsal tracheal ligament first and sub-
paired sterno cephalicus and sternohyoid muscles are sequently in the ventral tracheal rings; however, the dorsal

Resection and
8.16 anastomosis of the
cervical trachea in a Domestic
horthaired cat for management
of segmental tracheal stenosis at
the site of a previous temporary
tracheostomy (head to the right
in all images). (a) A ventral
midline exploration revealing the
stenotic segment of trachea.
(b) Following tracheotomy, a
sterile endotracheal tube has
been placed in the distal trachea
to maintain anaesthesia and
(a) (b) oxygenation. (c) Following
resection of the stenotic
segment, the orotracheal tube
has been advanced from the
proximal to the distal trachea
and simple interrupted sutures
have been preplaced ready to
perform the anastomosis. (d) The
distal and proximal sections of
the trachea have been apposed
and the sutures in the cartilage
ring have been tied to achieve
the anastomosis; the sutures in
the dorsal tracheal ligament are
tied last.
(c) (d)

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