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Tobias ECVS > Ch 105 - Thoracic Cavity > Flashcards

Ch 105 - Thoracic Cavity Flashcards

1
Q

What is normal plural fluid volume in dogs and cats?

A
  • Dog - 0.1ml/kg
  • Cats: 0.3ml/kg
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2
Q

What cells make up normal plueral fluid?

A
  • mesothelial cells 9-30%
  • Monocytes/macrophages 61-77%
  • Lymphocytes 7-11%
  • Neutrophils under 2%

1500-2500 cells/mcL
Protein less than 2.5g/dL

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3
Q

What % of dogs have a dorsal thoracic lymph centre?

A

25%

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4
Q

Which parts of the body are NOT drained by the thoracic duct?

A
  • Right thoracic limb
  • Right shoulder
  • Cervical regions

Drained by the right lymphatic duct

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5
Q

What is the cisterna chyli and where is it located?

A
  • Bipartite, dilated, retroperitoneal lymph channel, ventral to L1-L4 along cranial abdominal aorta
  • Most commonly sits ventral to L3, caudal to coeliac and cranial mesenteric arteries
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6
Q

What is the major difference in the thoracic duct anatomy in dogs and cats?

A
  • Dogs - travel on right sife through caudal thorax, dorsolateral to aorta. Crosses to left at T5/6
  • Cats: On the left!
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7
Q

Where does the thoracic duct drain?

A

Left external jugular vein or jugulosubclavian vein
(Significant anatomical variation - some branches may terminate in azygous)

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8
Q

What embryonic structure forms the thymus?
At what age does it stop growing and starts to involute?

A
  • Arises from the 3rd pharyngeal pouch
  • Grows until 4-5mo
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9
Q

What is the normal functional residual capacity (volume of air remaining in lung at end of expiration)

A

45ml/kg

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10
Q

What fluid dynamics favour pleural fluid production and absorption?

A
  • Increased hydrostatic pressure of systemic and pulmonary capillaries compared to pleural fluid favours pleural fluid production
  • Increased osmotic pressure of systemic and pulmonary vascular beds are greater than pleural fluid, favouring absorption

Tends to enter pleural space from parietal pleura and be absorbed by visceral pleura

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11
Q

What are the functions of the thymus?

A

Cell mediated immunity
- maturation and selection of T-cells
- Termination of defective or autoreactive thymocytes

Endocrine
- Secretion of thymosin, thymic humoral factor, thymopoietin, thymostimulin, thymulin
- Involved in T-cell enhancement and maturation

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12
Q

How do you classify pleural transudate, modified transudate and exudate?

A
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13
Q

List causes of a pleural transudate

A
  • Hypoproteinaemia
  • Increased hydrostatic pressure as with CHF (NT-proBNP significantly higher in cats with effusion from heart disease)
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14
Q

List DDx for a serosanguinous (modified transudate) effusion

A
  • Lung lobe torsion
  • D-hernia with liver entrapment
  • Pericardial effusion
  • Right sided heart failure
  • Neoplasia (diffuse mesothelioma or carcinomatosis)
  • Idiopathic pleuritis
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15
Q

List DDx for a sanguinous effusion

A
  • Trauma
  • Coagulopathy
  • Acute lung lobe torsion
  • Iatrogenic
  • Tumours (chemodectoma, right atrial HSA)
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16
Q

List DDx for chylous effusion

A
  • Any condition that increases hydrostatic pressure in the cranial vena cava
  • Trauma
  • Idiopathic
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17
Q

How do you confirm chylothorax?

A
  • Triglycerides higher and cholesterol lower than serum
  • Chylomicrons in the fluid can be stained with Sudan black
  • Positive ether clearance test
  • Modified transudate (protein 2.5-4g/dL, cell count less than 7000/mcL, specific grav leass than 1.032

Pseudochylus has higher cholesterol and lower triglycerides, and absent chylomicrons.

18
Q

List DDx for inflammatory effusion

A
  • D-hernia
  • Neoplasia
  • Chronic chylothorax
  • Lung lobe torsion
  • Infectious disease
  • Pancreatitis
  • Penetrating FB
  • Oesophageal trauma
  • Repeat thoracocentesis
  • Surgery

Oropharyngeal flora are most commonly isolated from cats

19
Q

What is the reported rate of pneumothorax and haemorrhage after a CT-guided lung FNA?

A
  • Pneumothorax 0-27%
  • Haemorrhage up to 30%

Usually minimal and require no treatment

20
Q

What is the most realiable way to differentiate transudates and exudates in cats?

A
  • Pleural fluid lactate dehydrogenase
  • Ratio of pleural fluid to serum TP.

Senstivity, specificity and accuracy 100% with a cut off for lactate at 226IU/L
Accuracy of TP ratio 95% with a cutoff greater than 0.56

21
Q

What is a reliable measurement to differentiate transudate and exudate in dogs?

A

C-Reactive Protein
- Greater than 4mcg/ml 100% sensitive and 94% specific
- 11mcg/ml 88% sensitive and 100% specific for differentiating modified transudate and exudate

22
Q

What intercostal space is used for thoracocentesis?

A

7th-9th

23
Q

What effect does mechanical ventilation have on the lungs and heart?

A
  • In closed chest, increases intrapulmonary pressures to 3-5cmH2O
  • This decreases coronary circulation, pulmonary circulation and venous return to the heart
  • Inspiratory:expiratory phases should be kept between 1:2 to 1:3
24
Q

In which intercostal space is a thoracostomy tube placed?

A

7th or 8th

25
Q

What is the recommended amount of crossing of a finger-trap

A

Spaced apart approx equal to width of tube with atleast 6 crosses on each side

26
Q

What has been shown to be more effective at preventing leakage around the chest tube?

A
  • Trocar tipper tube for tunneling rather than Carmalt forceps
  • Polyvinyl tubes more effecting than red rubber
27
Q

What is the recommended ICS for surgical approach to the following structures
- Heart and pericardium
- PDA, PRAA
- Pulmonic valve
- Cranial lung lobe
- Middle lung lobe
- Caudal lung lobe
- Cranial oesophagus
- Caudal oesophagus
- Cranial vena cava
- Caudal vena cava
- Thoracic duct in dog and cat

A
28
Q

What pressure is continuous suction usually maintained at for a thoracostomy tube?

A

5-10cmH2O

29
Q

What is the motality rate of thoracotomies?
What factors are associated with nonsurvival?

A

Mortality rate 13-22% (5.9% in another study)
Factors assoc with nonsurvival:
- Preanaesthetic O2 requirement
- Use of neuromuscular blocking agents during anaesthesia
- Surgical duration over 180min
- Blood products

30
Q

What is the mortality rate of thoracic trauma?

A
  • 11-15.5% with extensive bite wound trauma
  • 63% survival in cats
31
Q

List DDx for spontaneous pneumonthorax

A
  • Bullae/blebs
  • Emphysema
  • Neoplasia
  • Pleuritis
  • Migrating plant material
  • Pulm abscess
  • Feline asthsma or inflammatory airway disease (most common cause in cats)
  • Chronic pneumonia
  • Heartworm, lungworm

Siberian Huskies overrepresented

32
Q

What is the outcome of autologous blood patching for spontaneous pneumothorax?

A
  • Resolved pneumothorax in 7/8 dogs after 1-3 treatments (5-10ml/kg blood)
33
Q

What is the recurrence rate and mortality rate of spontaneous pneumo in dogs treated conservatively vs surgically

A
  • Conservatively 50% recurrence, 53% mortality
  • Surgically 3% recurrence, 12% mortality
34
Q

What do desquamated mesothelial cells make with chronic chylothorax?

A
  • Type III collagen promoting fibrosis and leading to Fibrosing Pleuritis
35
Q

What are the surgical options for chylothorax?

A
  • Thoracic duct occlusion/embolisation
  • Pericardiectomy
  • Cisterna chyli ablation
  • Omentalisation
36
Q

WHat is the prognosis for idiopathic chylothorax?

A
  • Thoracic duct attenuation alone: 50-59% dogs, 14-53% cats successful
  • Thoracic duct and subphrenic pericardiectomy: 55-100% dogs, 80% cats
  • Thoracoscopic duct ligation and pericardial window 83-86%
  • Thoracic duct and cisterna chyli 63-88%
  • Thoracic duct, percardiectomy and omentalisation 57-77%
37
Q

What are the options for managing recurrent chylous effusion?

A
  • Percutaneous drainage systems (Pleuraport)
  • Pleuroperitoneal shunts
38
Q

What breed is predisposed to pyothorax?

A

Labs and English Pointers

39
Q

What is the prognosis of pyothorax?

What factors are associated with increased survival in cats?

A

Successful Tx in 47.8 - 86%
85% disease free at 6m and 78% at 1yr post-op
Factors assoc with increased survival in cats:
- Lower resp rate
- Higer heart rate
- Higher WBC counts

40
Q

What breeds are overrepresented with thymoma?
What paraneoplastic syndromes are common?
How many have concurrent nonthymic neoplasia?

A
  • Labs and Goldens
  • Myaesthenis gravis (up to 47%), hypercalcaemia, feline exfoliative dermatitis (generalized severe desquamation)
  • 27% concurrent nonthymic neoplasia
41
Q

How can you differentiate thymoma and lymphoma on cytology?

A
  • Both contain large numbers of lymphocytes
  • Thymoma will more consistently have epithelial cells which may also exfoliate mast cells, eosinophils and erythrocytes
  • Flow cytometry

Tobias ECVS (110 decks)

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