Page 31 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

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

Pleural space disorders mechanical dysfunction of the chest wall. For this reason,
management is typically medical through oxygen supple-
Pleural effusion, pneumothorax and diaphragmatic hernia
VetBooks.ir are the most common pleural space disorders associated if the latter is required for other reasons.
mentation, pain management and judicious fluid therapy,
with respiratory distress. The clinical signs of pleural space
disease are a result of the underlying disease process and
the restriction of lung expansion. The latter is typically mani-
fested by short and shallow respirations and decreased Prolonged oxygen therapy
lung sounds on auscultation. In the authors’ experience,
pleural effusion is the most common of the three. Enclosed techniques
With enclosed techniques, oxygen is pumped into a con-
Pleural effusion tained area over the head or muzzle of the animal. Most
There are a variety of causes of pleural effusion (see oxygen masks are made of transparent plastic, through
Chapter 12). The diagnosis of the underlying cause of which the animal can be observed. Several methods have
been described by which increased inspired concen-
pleural effusion can be narrowed down and usually def-
initively determined by analysis of the pleural effusion (see trations of oxygen can be achieved, including placement of
the BSAVA Manual of Canine and Feline Clinical Pathology). a plastic bag over the head into which oxygen is pumped,
and the use of an Elizabethan collar with plastic wrap
covering the front. Advantages of these systems include
Pneumothorax their relative ease of use and rapid placement in emer-
Pneumothorax (see Chapter 12) is the second most gency situations. Depending on flow rates and tightness of
fit, very high oxygen concentrations can be achieved whilst
common pleural space disorder and is typically categorized
by aetiology, i.e. spontaneous (non-traumatic) or traumatic. access to the rest of the patient is still possible. Severely
Spontaneous pneumothorax most commonly occurs in dyspnoeic or very mobile patients may, however, not
tolerate these systems, and build-up of excessive heat and
large-breed dogs and is usually secondary to a pulmonary
parenchymal abnormality, such as a bulla, bleb or abscess. carbon dioxide due to excessive dead space as well as
These patients often present in severe respiratory distress, accumulated moisture, and water in panting dogs, can limit
their usefulness or even lead to respiratory acidosis.
with bilaterally diminished respiratory sounds dorsally. A
large amount of air is often obtained during thoraco -
cen tesis. Both sides of the thorax should be aspirated. Air Nasal tube
should be removed until a negative result is obtained. If a For administration of oxygen by nasal tube, a rubber
negative result cannot be obtained, then chest tubes should urinary catheter or soft polythene nasal feeding tube is
be placed and a constant vacuum applied. commonly used. Catheters may vary in size from 5 to 10
Tension pneumothorax occurs when air continues to Fr, depending on the size of the animal.
accumulate in the pleural space due to a one-way valve The catheter is measured from the nares to the medial
effect at the leak. Air continues to accumulate, causing canthus of the eye, and marked with a small piece of tape.
intrapleural pressures greater than atmospheric, resulting Following desensitization of the nostril, the lubricated
in progressive atelectasis, interference with venous return catheter is inserted gently into the nostril in a ventromedial
and poor cardiac output. Immediate relief of the pneumo- direction and advanced to the marker. Once the catheter is
thorax is required. A small intercostal incision into the in place, it is bent around and placed under the alar fold of
pleural space may rapidly relieve the pneumothorax. After the nostril, and sutured or glued in place on the side of the
removal of the air, the incision should be sealed with a face (Figure 2.4). For the most secure placement, a suture
sterile dressing, and close monitoring for reoccurrence of should be placed as close to the nasal–cutaneous junction
the pneumothorax should be instituted. Chest tube place- as possible. The nasal catheter is attached to an oxygen
ment is usually required in patients where a negative delivery system, with flow rates of 100–200 ml/kg/min.
pressure cannot be achieved during thoracocentesis or
when large amounts of air repeatedly accumulate.

Diaphragmatic rupture
Rupture of the diaphragm (see Chapter 17) is most
commonly caused by blunt trauma. The respiratory signs
are usually a result of restricted expansion of the lungs,
although underlying pulmonary contusions may contribute.
A diagnosis can be achieved by thoracic radiography, upper
gastrointestinal positive contrast radiography, abdominal
ultrasonography or intraperitoneal positive contrast imag-
ing. Surgery is the definitive therapy.

Thoracic wall disorders
The two most common thoracic wall disorders are rib
fractures and flail chest. Fractured ribs are relatively
easily diagnosed by radiographic evaluation, but can be
missed if the index of suspicion is not kept high. The Nasal oxygen can be provided through a catheter inserted
respiratory signs are more typically a result of the under- 2.4 into one nostril to a premeasured length.
lying pulmonary contusion and pain rather than the (Reproduced from the BSAVA Manual of Canine and Feline Emergency and Critical Care, 3rd edn)

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