Page 1577 - Cote clinical veterinary advisor dogs and cats 4th

792 Pleural Effusion

• Chylothorax: compare effusion and serum • Hydrothorax: for modified transudate periodically over several hours rather than
triglyceride and cholesterol concentrations (effusion total protein = 2.5-5 g/dL; no all at once and more likely with chronic
VetBooks.ir FIP unlikely (exception: if protein clot forms rhage), consider ○ Pleural shock: sudden bradycardia of
effusions
cytologic evidence of infection or hemor-
• FIP: albumin/globulin ratio of > 0.8 makes
vagal origin caused by needle contact
○ Heart disease: echocardiography (p. 1094),
in vitro, false-negative), positive Rivalta test
NT-pro-BNP (p. 1369)
suggests FIP (p. 327)
• Hemothorax: compare packed cell volumes ○ Thoracic mass: thoracic ultrasound exam, with the pleura (no prevention; responds
to immediate administration of atropine
(PCVs) (peripheral and effusion) CT (useful for identifying and character- 0.04 mg/kg IV)
Thoracic radiographs: signs of pleural effusion izing pleural space lesions; post-contrast ○ Bronchopleural fistula: constrictive/
vary with fluid volume; at a minimum, two- images can help delineate pleural lesions fibrosing pleuritis prevents further lung
view thoracic radiography is recommended from effusion), fine-needle aspiration and expansion during thoracocentesis, and
in all cases, but three-view radiographs are cytologic exam of lung or mass if lesion ongoing fluid withdrawal creates exces-
preferred: is identified (p. 1113), thoracoscopy or sive negative pressure in the pleural space;
• Radiographic changes: first apparent with thoracotomy for pleural or lung biopsy rupture of the bronchial wall into the
approximately 10 mL/kg of fluid • FIP (p. 327) pleural cavity may occur (possibly less
• General: retraction (scalloping) of lungs from • Chylothorax (p. 172) likely to occur if large-volume effusions
thoracic wall with interposed fluid opacity, • Hemothorax (p. 436) are withdrawn periodically over several
obscured diaphragm, widened mediastinum; • Pyothorax (p. 857) hours rather than all at once), especially if
with trauma, fractured ribs, diaphragmatic lung lobes are very round on radiographs
hernia, and orthopedic injuries may be TREATMENT
present Recommended Monitoring
• Specific views: dorsoventral (DV) view: Treatment Overview • Clinical signs, including respiratory rate
obscured cardiac silhouette; lateral view: Thoracocentesis is commonly needed acutely • Thoracic radiographs to assess resolution or
increased opacity dorsal to the sternum to improve respiratory function. Ultimately, progression
and scalloping of lung margins (lateral view correction of the underlying disease provides • Daily cytologic exam/Gram stain of chest
prone to misinterpretation); ventrodorsal the best chance for resolution of effusion. tube fluid withdrawn from pyothorax cases
(VD) view: visualization of small volumes, to assess antimicrobial response
blunting of lung margins and costophrenic Acute General Treatment
angles; horizontal beam: may reduce patient • Oxygen supplementation (p. 1146) if PROGNOSIS & OUTCOME
stress dyspneic
• Pyothorax/chylothorax: may cause fibrosing • Minimize stress • Varies with cause and severity of underlying
pleuritis; prevents full expansion of lungs • Thoracocentesis disease (e.g., grave prognosis for FIP, good
after thoracocentesis with rounded lung • Specific acute treatment as indicated by type/ prognosis for hemothorax due to coagulopa-
lobe contours. Difficult to distinguish from cause of pleural effusion thy after initial stabilization)
effusion • Support of circulatory and respiratory • Pleural effusion may worsen the short-term
• Radiographs after thoracocentesis recom- function prognosis for the underlying disease by
mended to evaluate for underlying disease causing acute respiratory compromise.
(improved visualization) Chronic Treatment
Clinicopathologic abnormalities (depend on Correction of the underlying disorder may PEARLS & CONSIDERATIONS
cause): resolve effusion with or without repeated
• CBC: inflammatory leukogram, thrombo- thoracocentesis. See specific disease condition Comments
cytopenia, anemia with some causes for treatment information. • If pleural effusion is suspected, consider
• Serum biochemical panel: depending • Chronic effusions refractory to therapy: thoracocentesis, which can be diagnostic
on cause, may find hypoalbuminemia, consider placement of a PleuralPort device, and therapeutic, before thoracic radiographs.
hypoglobulinemia/hyperglobulinemia, which allows owners to drain the effusion • Thoracic percussion may increase suspicion of
hypoglycemia, hypocholesterolemia, azote- at home using a Huber needle placed into pleural effusion and supports pre-radiograph
mia, electrolyte abnormalities, or increased a subcutaneous drainage hub. thoracocentesis.
liver enzyme concentrations • Even partial drainage of the effusion can
• Urinalysis: proteinuria if protein-losing Possible Complications improve respiratory function.
nephropathy • Iatrogenic pneumothorax and hemothorax • Obtain dorsoventral view first, which is often
Thoracic ultrasonography (p. 1102) from thoracostomy tube sufficient to confirm effusion.
• Before thoracocentesis to improve the acoustic • Constrictive/fibrosing pleuritis (pyothorax ○ Alternatively, a brief ultrasound exam
window, unless the animal is uncomfortable/ or chylothorax) may confirm pleural effusion, justifying
dyspneic during restraint for the exam • Disseminated intravascular coagulation thoracocentesis. Radiographs may then be
(DIC) or systemic inflammatory response taken more safely after thoracocentesis.
Advanced or Confirmatory Testing syndrome (SIRS) from pyothorax ○ Ultrasonography with patient in sternal
Testing is based on nature of effusion and prior • Recurrence of pyothorax if migrating foreign recumbence or standing can visualize
diagnostic test results: body remains or inappropriate antibiotics are effusion with minimal restraint and stress.
• Hydrothorax: for pure transudate (effusion used or used for an insufficient duration • Because cats with pleural effusion can be
total protein < 2.5 g/dL, total nucleated cell • Complications of thoracocentesis (and easily stressed by radiographs, consider
count < 1000), consider corresponding precautions) include: thoracocentesis early (especially if para-
○ Protein-losing nephropathy: urine protein/ ○ Lung laceration and pneumothorax: doxical breathing occurs without expiratory
creatinine ratio less likely if needle is introduced and wheezing).
○ Hepatic failure/portal systemic shunt: bile withdrawn in linear fashion, without • Hemothorax usually develops from trauma,
acids/ammonia, abdominal imaging side-to-side or rotatory motions after the coagulopathies, or neoplasia.
○ Protein-losing enteropathy: serum folate/ needle tip is in the pleural space • Grass awns can be located in multiple sites,
cobalamin, intestinal biopsies (surgical or ○ Re-expansion pulmonary edema: less likely including the pericardial sac, in dogs with
endoscopic) if large-volume effusions are withdrawn pyothorax.

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