Page 340 - Small Animal Internal Medicine, 6th Edition

312 PART II Respiratory System Disorders

occur in the presence of inflammation and should not be ensure that every lobe is examined. BAL is routinely per­
confused with neoplasia. Sometimes the liver is aspirated formed as part of diagnostic bronchoscopy after thorough
VetBooks.ir inadvertently, particularly in deep­chested dogs, yielding a visual examination of the airways. The reader is referred else­
where for details about performing bronchoscopy and bron­
population of cells that may resemble those from adenocar­
cinoma. However, hepatocytes typically contain bile pigment.
McKiernan, 2005; Padrid, 2011). Bronchoscopic images of
Bacterial culture is indicated in some animals, although the choscopic BAL (Dear and Johnson, 2013; Hawkins, 2004;
volume of material obtained is quite small. normal airways are shown in Fig. 20.27. Reported cell counts
Transthoracic lung core biopsies can be performed in from bronchoscopically collected BAL fluid are provided in
animals with mass lesions immediately adjacent to the Table 20.3.
chest wall. Specimens are collected after an aspirate has Abnormalities that may be observed during bronchos­
proved to be nondiagnostic. Needle biopsy instruments copy, and their common clinical correlations are listed in
can be used (e.g., EZ Core biopsy needles, Products Group Table 20.4. A definitive diagnosis is rarely possible on the
International, Lyons, Colorado). Smaller­bore, thin­walled basis of the findings yielded by gross examination alone.
lung biopsy instruments can be obtained from medical Specimens are collected through the biopsy channel for cyto­
suppliers for human patients. These instruments collect logic, histopathologic, and microbiologic analysis. Bronchial
smaller pieces of tissue but are less disruptive to normal specimens are obtained by bronchial washing, bronchial
lung. Ideally, sufficient material is collected for histo­ brushing, or pinch biopsy. Material for bacterial culture can
logic evaluation. If not, squash preparations are made for be collected with guarded culture swabs. The deeper lung is
cytologic studies. sampled by BAL or transbronchial biopsy. Foreign bodies are
removed with retrieval forceps.
BRONCHOSCOPY
THORACOTOMY OR THORACOSCOPY
Indications WITH LUNG BIOPSY
Bronchoscopy is indicated for the evaluation of the major
airways in animals with suspected structural abnormalities, Thoracotomy and surgical biopsy are performed in animals
for visual assessment of airway inflammation or pulmonary with progressive clinical signs of lower respiratory tract
hemorrhage, and as a means of collecting specimens in disease that has not been diagnosed using less invasive
animals with undiagnosed lower respiratory tract disease. means. Although thoracotomy carries a greater risk than the
Bronchoscopy can be used to identify structural abnormali­ previously mentioned diagnostic techniques, the modern
ties of the major airways, such as tracheal collapse, mass anesthetic agents, surgical techniques, and monitoring capa­
lesions, tears, strictures, lung lobe torsions, bronchiectasis, bilities now available have made this procedure routine in
bronchial collapse, and external airway compression. Foreign many veterinary practices. Analgesic drugs are used to
bodies or parasites may be identified. Hemorrhage or inflam­ manage postoperative pain, and complication­free animals
mation involving or extending to the large airways may also are discharged as soon as 2 to 3 days after surgery. Surgical
be seen and localized. biopsy provides excellent­quality specimens for histopatho­
Specimen collection techniques performed in conjunc­ logic analysis, culture, PCR, and other specific tests for infec­
tion with bronchoscopy are valuable diagnostic tools because tious diseases or neoplasia. Abnormal lung tissue and
they can be used to obtain specimens from deeper regions accessible lymph nodes are biopsied.
of the lung than is possible with the tracheal wash technique, Excisional biopsy of abnormal tissue can be therapeutic
and visually directed sampling of specific lesions or lung in animals with localized disease. Removal of localized neo­
lobes is also possible. Animals undergoing bronchoscopy plasms, abscesses, cysts, and foreign bodies can be curative.
must receive general anesthesia, and the presence of the The removal of large localized lesions can improve the
scope within the airways compromises ventilation. Therefore matching of ventilation and perfusion, even in animals with
bronchoscopy is contraindicated in animals with severe evidence of diffuse lung involvement, thereby improving the
respiratory tract compromise unless the procedure is likely oxygenation of blood and reducing clinical signs.
to be therapeutic (e.g., foreign body removal). In practices where thoracoscopy is available, this less
invasive technique can be used for initial assessment of intra­
TECHNIQUE thoracic disease. Similarly, a “mini” thoracotomy can be per­
Bronchoscopy is technically more demanding than most formed through a relatively small incision. If disease is
other endoscopic techniques. The patient is often experi­ obviously disseminated throughout the lungs such that sur­
encing some degree of respiratory compromise, which poses gical intervention will not be therapeutic, biopsy specimens
increased anesthetic and procedural risks. Airway hyper­ of abnormal tissue can be obtained with these methods via
reactivity may be exacerbated by the procedure, particularly small incisions. If access by thoracoscopy or “mini” thora­
in cats. A small­diameter, flexible endoscope is needed and cotomy is insufficient based on initial findings, these proce­
should be sterilized before use. The bronchoscopist should dures can be transitioned to a full thoracotomy during the
be thoroughly familiar with normal airway anatomy to same anesthesia.