Pleural Cavity Diseases Flashcards
What is the function of pleural fluid? How is it formed?
lubricated the lungs and allows the diffusion of substances, like electrolytes
when plasma exits from capillary beds in the tissue and enters the interstitial space
Where is pleural fluid formed and absorbed?
parietal surface
visceral surface
What is pleural effusion? What are the 4 mechanisms of fluid accumulation?
accumulation of excessive amounts of fluid within the pleural space from excess fluid production and/or decreased lymphatic absorption
- decreased oncotic pressure - hypoalbuminemia
- increased hydrostatic pressure - CHF
- increased capillary membrane permeability - inflammation due to FIP, neoplasia, pyothorax, or vasculitis
- lymphatic malfunction - obstruction, lymphangiectasia
How does pleural effusion cause clinical signs? What signs are the most common?
interferes with normal lung expansion
- restrictive breathing pattern (rapid, shallow, orthopnea, open mouth)
- dyspnea, cyanosis
- increased respiratory effort
- exercise intolerance
- pyrexia, anorexia, lethargy
What is the normal pressure of the pleural cavity? How does effusion affect this?
negative pressure, which works with surfactant to keep the lungs inflated
as pleural fluid accumulates, there is a gradual collapse of the lung parenchyma and an increase in intrathoracic pressure
Usually, once pleural effusion is removed, lungs refill. What is an exception?
when fibrin and scarring forms around lung edges from chronic inflammation and prevent re-expansion of lung tissue
What is commonly heard on auscultation in patients with pleural effusion? What signs should be looked for? What should especially be done on physical exams of cats?
muffled heart and ventral lung sounds, with increased lung sounds dorsally —> fluid accumulates ventrally, air remains dorsal
signs of CHF and neoplasia
compression of the anterior thorax to investigate possible mediastinal masses (which cause effusion)
How do lungs look on thoracic radiographs with pleural effusion?
outlined due to the presence of fluid between them and the body wall
What is the recommended immediate treatment for patients in distress with suspected pleural effusion?
thoracocentesis (treatment/diagnostic) before radiographs
- especially in cats
What is the recommended area for thoracocentesis? What equipment is commonly used?
between 7th and 8th ribs caudal to the costochondral junction
butterfly with 3-way stopcock (butterflies can take a while, but they prevent going too far in)
What is the difference in thoracocentesis technique in smaller and larger patients?
SMALL = oblique angle
LARGE = horizontal
(advance the needle slightly ventrally)
What should be done after turning the stopcock to perform thoracocentesis?
GENTLE SUCTION - no more than 2 mLs of negative pressure
(extension tubing can be used to allow independent movement of syringe)
After all of the fluid is attained from thoracocentesis what should be done?
- submit fluid for analysis
- take post-procedure radiographs or US
What is transudate? What cell types are most common?
transparent pleural effusion that is typically transparent and low in protein (<2.5-3 g/dl) and cells (<500-1000 /uL)
mononuclear cells - macrophages, lymphocytes, mesothelial cells
What is modified transudate? What cell types are the most common? What is it suggestive of?
serosanguinous pleural effusion with slightly higher protein (~3.5 g/dl) and cells (1000-5000 /uL) compared to transudate
neutrophils
obstructive effusion
What is exudate? What causes its accumulation? What is a key part to its diagnosis?
red, brown, yellow, or opaque pleural effusion with high protein (>3 g/dl) and cells (>5000 uL)
increased capillary permeability due to inflammation
aerobic and anaerobic cultures with susceptibility
What is pyothorax? When does the exudate typically have a foul odor? What causes sulfur granule accumulation?
septic pleural effusion with extremely elevated cell counts consisting of degenerate neutrophils and bacteria
if anaerobes are present
Nocardia and Actinomyces infection
What are the 4 most common causes of pyothorax in cats? What bacteria are the most common causes?
- penetrating bite wounds
- oropharyngeal aspiration
- upper respiratory infection
- foreign body (grass awn)
Pasteurella, Bacteroides, Fusobacterium
What are the 3 most common causes of pyothorax in dogs? What bacteria are the most common causes?
- inhaled foreign bodies
- penetrating injury
- pneumonia
Actinomyces, Nocardia
What do non-septic exudates typically look like? What are the 4 most common causes?
thick, yellow/straw-colored, rich in protein
- FIP
- chylothorax/hemothorax
- neoplasia
- lung torsion
What cell types are commonly seen in non-septic exudates?
VARIABLE
- neutrophils
- macrophages
- eosinophils
- lymphocytes
How is hemorthorax diagnosed?
red exudate gained on thoracocentesis that clears on centrifugation and has a hematocrit 1/4 that of the peripheral blood
- most commonly cause by trauma and neoplasia
What is the recommended medical treatment of pyothorax?
- drainage and chest tube placement +/- continous suction and lavage
- long-term antibiotics based on culture and sensitivity
What antibiotics are recommended for anaerobes, Gram-negative, Nocardia, and Actinomyces/Pasteurella? What should be done if there is no improvement in 3-4 days?
amoxi/sulbactam, penicillins, metronidazole, clindamycin
baytril (enrofloxacin)
penicillins
exploratory to search for foreign bodies or abscesses with thorough lavage
What should be done before discontinuing antibiotics in cases of pyothorax?
monitor x-rays and/or ultrasound to evaluate resolution
- also take another one about 2 weeks after
When is surgical management of pyothorax recommended? What should be done before surgery?
if a pulmonary abscess or foreign body is suspected
try bronchoscopy to see if foreign material can be removed prior
What types of diseases have the ability to cause chylothorax? What breeds are predisposed?
those that increase systemic venous pressure, since chyle empties into the venous system near the cranial vena cava
- Afghan hounds
- Mastiffs
- Shelties
- Oriental breed cats`
What is chyle?
milky fluid consisting of proteins, fat, and white cells, specifically triglycerides and lymph —> drains from the lacteals of the small intestine into the lymphatic system during digestion
What are the most common traumatic, neoplastic, cardiac, inflammatory, and respiratory causes of chylothorax?
rupture of thoracic duct
cranial mediastinal masses cause obstruction of thoracic duct as it enters the jugular vein or cranial vena cava
cardiomyopathy, right-sided heart failure, pericardial disease, heartworm
fungal
torsion
How does thoracic duct lymphangiectasia cause chylothorax?
causes transmural leakage across the intact, but dilated vessel
What is the most common cause of chylothorax?
idiopathic in Afghan hounds, Mastiffs, Shelties, and oriental cat breeds
What does chylous effusion typically look like? What are the predominant cell types? How is a definitive diagnosis reached?
milky white (chylomicrons) or strawberry milk color that does not clear with centrifugation —> in anorexic patients, it can be lighter!
lymphocytes —> chronic = non-degenerate neutrophils, macrophages, mesothelial cells
detection of triglyceride levels in fluid 2x serum levels
What should be included in the workup for possible chylothorax in cats?
echocardiogram —> idiopathic is common, but underlying cardiomyopathy and heartworm should be tested
What neutraceutical is recommended for managing chylothorax? What does it do?
rutin
- increases uptake of edema fluid by lymphatics
- stimulates macrophage activity to breakdown proteins in lymphatic fluid (improves reabsorption)
What diet is recommended for managing chylothorax?
low fat to decrease the lipid content of chyle, which can allow it to be reabsorbed easily
- patients also tend to have deficiencies of protein and fat-soluble proteins, so a balanced nutritional plan is necessary
In what 3 situations is surgical treatment of chylothorax recommended? What is the technique of choice?
- failure of conservative, medical management
- loss of chyle > 20 mL/kg/day over 5 days or persistence of over 4 weeks
- protein malnutrition/hypoproteinemia
thoracic duct ligation
What are 3 other optional surgical treatments of chylothorax?
- subtotal pericardiectomy - chylothorax can be secondary to conditions that increase right-sided venous pressure
- cisterna chyli ablation - refractory to surgery
- port placement, pleural-peritoneal shunt
What is a common sequelae to chylothorax?
restrictive pleuritis, where a thick fibrinous membrane or granulation tissue forms in the visceral pleura —> encasement restricts expansion of the lungs and results in respiratory compromise despite pleural drainage
What clinical sign and radiography findings leads to a diagnosis of restrictive pleuritis?
persistent respiratory difficulty after removal of pleural fluid
fibrosing pleural space causing collapse and rounded edge to lung lobes
How does the cell type change with chronic hemothorax?
- neutrophils and macrophages increase
- erythrophagocytosis begins
What is the most common cause of hemothorax? What are some additional causes?
trauma
- coagulopathy (warfarin toxicity, low platelets)
- neoplasia rupture
- parasites
- lung lobe torsion
How can you tell the difference of fresh (frank) blood from free (older) blood in the chest?
FRESH = hit blood vessel, will clot in red top
FREE = will not clot due to defibrinization and platelet disappearance common after 8 hours
How is hemothorax diagnosed? Treated?
coagulation profile, radiographs, ultrasound abdomen and chest
- fluid support
- blood transfusion or auto-transfustion
- abdominal wrap
- surgery/thoracocentesis
What is the most common tumor affecting the pleural space?
mesothelioma
Why are neoplastic effusions difficult to diagnose? What is the exception?
- can result in any type of effusion
- neoplastic cells typically do not exfoliate well into effusion
- inflammation can make mesothelial cells seem dysplastic
lymphoma exfoliates well
What are the 2 types of pneumothorax?
- OPEN - communicates with external environment, commony caused by gunshots, bites, stab wounds, or rib fractures
- CLOSED - no breach of thoracic wall, commonly caused by HBC or complications of lung aspirates
What is the most common cause of pneumothorax? What are some spontaneous causes?
trauma
- tumors, abscesses, bullae rupture
- pneumonia
- Paragonimus, heartworm
- chronic bronchitis
- asthma
What are the most common causes of iatrogenic pneumothorax?
- chest taps
- intubation
- tracheal tear
- PEEP
What breeds are predisposed to idiopathic pneumothorax?
Huskies
What are the most common physical exam findings in patients with pneumothorax?
- dyspnea, tachypnea, open mouth breathing
- restrictive breathing pattern
- barrel-shaped chest
- muffles heart sounds, absent breath sounds**
- subcutaneous emphysema, flail chest
- hemoptysis, intra-alveolar/interstitial hemorrhage
- hypoventilation, hypoxemia
What are 5 radiographic findings in patients with pneumothorax?
- heart elevated from sternum
- collapsed lungs (opaque) that retract from the body wall
- absence of vasculature reaching chest wall
- dorsal displacement of heart and trachea
- increased density of collapsed lobe
What is the recommended treatment for pneumothorax? When is surgical intervention recommended?
emergency thoracocentesis if in respiratory distress (ideally before radiographs)
+ analgesia/anti-anxiety
+ oxygen to create a pressure gradient to drive free air into pleural blood
if pneumonia persists > 72 hours, typically due to large airway lacerations
How is thoracocentesis performed in cases of pneumothorax?
9th to 10th intercostal spaces above the costochondral junction
What are the 2 major indications for chest tube/drain placement?
- pyothorax
- pneumothorax where air continues to accumulate despite multiple thoracocenteses
