1.1.3: Pleural space disease

Question 1

An animal presents with difficulty breathing. Which areas could this be localised to?

Answer 1

1. URT obstruction
2. Loss of thoracic capacity = pleural space disease
3. Pulmonary parenchymal disease
4. Non-CRS conditions e.g. anaemia, heat stroke -> breathing tends to be rapid and shallow rather than dyspnoea per se

To identify which, use clinical exam. Ultrasound also helps.

Question 2

Conditions leading to loss of thoracic capacity ± cyanosis

Answer 2

• Pleural effusion
• Pneumothorax
• Neoplasia (pleural or mediastinal)
• Ruptured diaphragm
• Abdominal abnormality e.g. severe ascites, mass
• Gross cardiomegaly

Question 3

Pleural space disease

Answer 3

accumulation of fluid (pleural effusion), air (pnuemothorax), or soft tissue mass in the pleural space.

Question 4

How does pleural space disease lead to difficulty breathing?

Answer 4

• There is direct compression of the lungs by fluid/air/mass
• There is loss of negative pressure leading to lung collapse
• If fluid -> this restricts the ability of the lungs to inflate so is known as restrictive lung disease

Question 5

Clinical signs of pleural space disease

Answer 5

• Restrictive breathing pattern: short, shallow breaths, with the thorax and abdomen looking like a set of bellows (thorax in, abdo out, then thorax out, abdo in)
• Tachypnoea
• Open-mouthed breathing
• Dyspnoea
• Orthopnoea: elbow abduction, sternal recumbency; some CHF patients won’t lie down as abdominal contents restrict diaphragmatic movement
• Cyanosis
• May be acute or chronic

Question 6

What clinical exam findings might you expect from a patient with pleural space disease?

Answer 6

• Observe the characteristic restrictive respiratory pattern
• Muffled heart/lung sounds
• Percussion of chest e.g. fluid line in pleural effusion

Question 7

What effect could a mass in the mediastinum have on the apex beat?

Answer 7

A mass in the mediastinum could displace the heart and the apex beat

Question 8

Why might a pleural effusion form?

Answer 8

If there is:
* Decreased pleural fluid absorption into lymphatics
OR
* Increased fluid formation

Question 9

True/false: lung lobe torsion could cause chylothorax or haemothorax.

Answer 9

True
* Chylothorax -> occurs if there is disruption to the thoracic duct
* Haemothorax -> occurs if there is bleeding

Question 10

Exudate

Answer 10

high cellularity and high protein.
e.g. FIP

Question 11

Answer 11

Pleural effusion
* Lungs float in fluid
* Diaphragmatic lung lobe especially may move
* The cardiac silhouette is obscured by fluid

Question 12

Answer 12

Pleural effusion

Question 13

Immediate treatment of pleural effusion

Answer 13

• Oxygen supplementation
• Emergency thoracic ultrasound
• If severely dyspnoeic do not radiograph - unstable and stressed!
• Thoracocentesis: provides immediate relief and stabilisation, can be diagnostic (cell counts, protein, bacterial culture)

Question 14

How to perform a thoracocentesis for pleural effusion

Answer 14

• Clip and quick surgical prep
• Butterfly needle/catheter at IC 6-8 (ICS 7 usually safe). Insert at level of the costochondral junction.
• Idealise localise a large pocket of fluid with ultrasound first.
• Use aseptic technique (colleague holds syringe while you remain sterile)

Question 15

Indications for thoracostomy and chest drain placement

Answer 15

• Animals that will require multiple thoracocentesis over a short period of time
• If large volumes of effusion
• If pneumothorax
• Chest wall injuries e.g. flail chest (portion of rib cage is separated from the rest)
• Bite wounds
• Most pyothorax cases - pus is hard to aspirate, in-dwelling chest drain allows periodical lavage
• Following chest surgery

Question 16

Management of pleural effusion

Answer 16

Depends on cause -> ideally treat primary cause where possible
* Heart failure -> treat where possible
* Pericardial effusion -> treat and drain
* Pyothorax -> chest drain and lavage, need broad spectrum + anaerobe antibiotic coverage
* Chylothorax -> diet and/or surgery

Question 17

Pneumothorax

Answer 17

accumulation of air within the thorax but outside the lung.

Question 18

True/false: rupture of the oesophagus can produce pneumothorax.

Answer 18

True

Question 19

Clinical signs of pneumothorax

Answer 19

• Restrictive breathing (slow to rapid breathing)
• Dull lung sounds dorsally (air rises to dorsal part of thorax)
• Increased lung sounds ventrally (lung gets compressed here)
• Percussion -> increased resonance (like a drum)

Question 20

Answer 20

Pneumothorax
* There is characteristic displacement of the heart caused by movement of the lung lobes ventrally
* The lung lobes have in turn been displaced by air
* Free air surrounds the collapsed lung lobes

Question 21

Diagnosis of pneumothorax

Answer 21

• Physical exam
• Assessment of respiratory status
• Radiographs if stable enough
• Thoracic ultrasound -> there is loss of the normal glide sign in pneumothorax

Question 22

Treatment of pneumothorax

Answer 22

• Provide oxygen
• Drain pnuemothorax: ICS 7-8; may have to drain 2-3 times but often good prognosis
• Strict cage rest for 2 weeks
• Some patients may require chest drains (a.k.a. in-dwelling thoracostomy tube)

Question 23

Answer 23

Diaphragmatic rupture

Question 24

Diagnosis of mediastinal masses

Answer 24

• Diagnostic imaging: CT - very useful for surgical planning
• If radiography -> may be hidden behind pleural effusion; check for displacement/tracheal position

Question 25

Answer 25

Mediastinal mass causing dorsal displacement of the trachea

Question 26

True/false: it is important to reach a definitive diagnosis for thoracic/mediastinal masses.

Answer 26

True
Diagnosis is very challenging but has a huge impact on treatment (e.g. treatment plan for lymphoma vs sarcoma)

Question 27

Signalment and treatment for mediastinal lymphoma

Answer 27

• Commonest in young cats; also seen in dogs with mutlicentric/ Stage 3-5 lymphoma
• Diagnosis: cytology
• Treatment: chemotherapy ± radiotherapy

Question 28

Thymoma signlament, diagnosis and treatment

Answer 28

• Signalment: overall rare, commonest in older dogs
• Metastasis is rare
• Diagnosis: thoracic rads to locate mass, then cytology (often require section of mass)
• Treatment: surgical resection

Question 29

Answer 29

Cranial caval syndrome
* If cranial vena cava is obstructed, venous return from the head and cranial body is restricted so there is oedema
* This dog had a cranial mediastinal mass affecting the cranial vena cava

Question 30

Treatment of thyroid masses

Answer 30

• Radioactive iodine or surgery
• If >3cm in diameter, radiotherapy may be better as prognosis is poorer

Question 31

Diagnosis of thyroid masses

Answer 31

Nuclear scintigraphy to confirm if active

Question 32

Diagnosis and treatment of pleural tumours

Answer 32

• Example: mesothelioma.
• As a whole, pleural tumours are rare
• Diagnosis: Ultrasound and CT; multifocal small masses - hard
• Treatment: intra-cavitary carboplatin/cisplatin. Painful, traumatic, poor prognosis

Question 33

Answer 33

Pleural effusion
* There is displacement of the lung lobes; the diaphragmatic lobe is floating in fluid away from the thoracic wall
* This is “heavy fog” with loss of the cardiac silhouette

Question 34

Types of rib tumours and treatment

Answer 34

• Types: osteosarcomas, chondrosarcomas, overlying soft tissue tumours e.g. infiltrative lipomas
• Treatment: rib resection e.g. thoracotomy and post op chemotherapy if osteosarcoma

Question 35

Answer 35

Cytology from pleural tumour e.g. mesothelioma