Page 173 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

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

Broad-spectrum antibiotics should be administered intra- Cats: In cats, medical treatment including thoracostomy
venously as soon as possible, especially if the patient tubes, intravenous fluids and intravenous antibiotic therapy
VetBooks.ir Medical management therapy, or if an obvious surgical lesion such as an
is usually successful. If a cat is not responding to medical
presents in septic shock.
abscessed lung lobe or foreign body is identified, surgical
Antimicrobials: Broad-spectrum antimicrobials active intervention is indicated. Failure of medical management
can be defined as the inability to aspirate effusion through
against Gram-positive, Gram-negative and anaerobic
properly placed and functional thoracostomy tubes or
bacteria are administered until culture and sensitivity failure of the effusion to resolve over a reasonable period
results are available. A broad-spectrum approach is
of time (usually a week).
appropriate because of the frequency with which dogs
and cats are infected with a mixed population of bacteria.
Antibiotics are administered intravenously whilst the Surgical treatment
patient is critical, but can be administered by the oral
In one study, dogs were shown to have improved outcomes
route once the patient has been stabilized and culture with surgical intervention for the treatment of pyothorax,
and sensitivity results are available. Appropriate antibiotic
and surgery should be considered sooner in this species
therapy should be continued for 1–2 months following than in cats, without first waiting for a response to medical
discharge from the hospital.
therapy (Rooney and Monnet, 2002). However, further
recent studies have shown excellent outcomes in dogs
Fluid therapy: This should be continued at maintenance without surgical intervention (Johnson and Martin, 2007)
rates or higher, depending on the amount of pleural effusion
or failed to support the finding that surgical treatment is
that is produced. Keeping the patient adequately hydrated superior to medical management (Boothe et al., 2010).
is essential in maintaining the effusion at a consistency that
Surgical treatment requires a complete exploratory
can be easily aspirated via thoracocentesis or thoracostomy thoracotomy. The goal is to identify and remove any
tubes. These patients often become hypoalbuminaemic and
necrotic tissue or foreign material, as well as to allow
may benefit from appropriate colloidal support.
complete lavage of the thoracic cavity. Samples for aero-
Drainage: Drainage of pleural effusion is one of the main- bic and anaerobic culture are obtained at surgery.
Options for surgical therapy include thoracoscopy (see
stays of therapy for patients with pyothorax. This can be
accomplished by intermittent thoracocentesis or by place- below), median sternotomy and, occasionally, lateral
thoracotomy (see Operative Technique 11.1). Advantages
ment of thoracostomy tubes, with intermittent aspiration or
continuous drainage (see above). Thoracostomy tubes of thoracotomy include full exploration of the thoracic
cavity and removal of all exudate from the pleural space
are preferred because they allow more complete drainage
of the thoracic cavity and are usually less stressful than the with lavage. Disadvantages include the increased cost
and length of stay in the hospital, the pain associated
restraint required for multiple thoracocentesis procedures.
Thoracos tomy tubes are best placed with the patient under with the thoracotomy and the risks associated with
general anaesthesia.
general anaesthesia, so initial stabilization with fluid therapy
and pleural drainage by thoracocentesis should occur Median sternotomy (see Chapter 11) allows a full eval-
before anaesthetizing what can be very critical patients. uation of the right and left hemithoraces. The lungs, peri-
Bilateral thoracostomy tubes are indicated unless the cardium, trachea, mediastinum, pleural surfaces and
patient only has a unilateral effusion, although success has lymph nodes can all be evaluated for signs of abscessa-
been reported with unilateral drainage in dogs (Johnson tion, bleeding, inflammation or leakage of air. Adhesions
and Martin, 2007). of fibrous tissue may need to be broken down to allow
complete evaluation, especially when looking for a pos-
Lavage: Lavage of the thoracic cavity has been recom- sible foreign body. Any necrotic, abscessed or severely
mended by many authors. Warm physiological saline inflamed tissue should be resected, including lung lobes,
or other balanced electrolyte solutions can be used at 20 lymph nodes, mediastinum and pericardium. A lateral
ml/kg, instilled over 10–15 minutes, q6–24h. Addition of thoracotomy is only indicated if the inflammatory process
anti biotics or other medications, including chymotrypsin, is limited to one hemithorax. Occasionally, the origin of
streptokinase and heparin, has been recommended in a unilateral pyothorax can be isolated to a single
various reports. Antibiotic therapy is most useful when abscessed lung lobe or foreign body, in which case a
admini stered intravenously. A recent retrospective study lateral thora cotomy may be preferred (Figure 12.8). When
found that there was increased survival in dogs treated the cause of the pyothorax cannot be identified or local-
medically if they received pleural lavage with 0.9% saline or ized to one side of the chest, a median sternotomy is the
lactated Ringer’s solution at 10–20 ml/kg, and also approach of choice. Even with surgical exploration of
increased survival if they received pleural lavage with the thoracic cavity, the underlying cause of the pyothorax
hep arin (10 IU/ml) compared with lavage without heparin is often not identified. Thoracostomy tubes, either uni-
(Boothe et al., 2010). However, this was a retrospective lateral or bilateral as indicated, should be placed at the
study with a number of limitations, so it is difficult to make time of the surgery.
recommen dations based on this report alone. A prospec- Thoracoscopy is a minimally invasive surgical proce-
tive ran domized study is needed to determine the true dure that can be used to explore the thoracic cavity. This
value of these therapies. Lavage can be performed at the technique has been recommended for assistance in treat-
time of placement of the chest tube if the pleural effusion is ment of pyothorax in humans and has resulted in shorter
too thick to aspirate easily through the tube. Risks of con- hospital stays when compared with thoracostomy tube
tinuing to lavage the chest tube during hospitalization drainage alone, thoracostomy tube drainage with fibrino-
include placing a large volume of fluid into the chest with- lytics, and thoracotomy. The role of thoracoscopy has not
out the ability to retrieve it and the potential introduction of been clearly defined for veterinary patients, but as the
a nosocomial infection res stant to the antimicrobials that technique becomes more commonly used similar treat-
i
the patient is already receiving. ment benefits may be identified.

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