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Small Animal Medicine > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

Pleural Space Disease

A 
Pneumothorax*  = air
Chylothorax* =  lymph
Pyothorax* = pus
Hemothorax = blood
Hydrothorax = "water" - pure transudate
Diaphragmatic hernia = organs
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2
Q

Radiographic signs of pleural effusion

A
  1. Gravity dependent soft tissue opacity

2. Fissure lines in the lungs

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3
Q

Pleural space

A
  1. Pleura: thin layer of mesothelial cells
    • visceral pleura covers lung surface
    • parietal pleura lines thoracic wall, diaphragm, mediastinum
    • small amount of fluid between layers normally (helps lungs expand when thorax expands)
  2. Pleural fluid volume determined by:
    • Starling’s forces (hydrostatic and oncotic pressure)
    • Lymphatic drainage
    • Mesothelial cells
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4
Q

Potential pleural effusion mechanisms

A
  1. Increased venous hydrostatic pressure (ie. CHF, thrombosis)
  2. Decreased oncotoic pressure
  3. Impairment of lymphatic drainage (increased venous pressure, lymphatic trauma, neoplasia, lung lobe torsion)
  4. Increased vascular permeability
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5
Q

Pleural effusion: physical exam

A

Pattern of dyspnea:
- RESTRICTIVE

Auscultation
- Muffled ventrally (gravity dependent fluid)

Pneumothorax: muffled dorsally, echo-like (air bubble rises)

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6
Q

Pleural Effusion: other physical exam parameters

A
  1. Other cardiopulmonary abnormalities (including jugular pulses)
  2. Thoracic compression (ie. cat mediastinal mass)
  3. Peripheral LN
  4. Abdominal palpation: masses, pain, ascites
  5. Fever
  6. Mucous membranes
  7. Cranial nerves (space occupying mass putting pressure on nerves causing Horner’s syndrome)
  8. BCS/muscle condition
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7
Q

Pleural Effusion (first step)

A
  1. Respiratory distress?
    ==> Yes = thoracocentesis
    ==> No = Thoracic imaging, minimum database
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8
Q

Thoracocentesis

A
  1. Sternal (ideal, not required; gravity dependent fluid will be symmetrical)
  2. Insert
    - ~7-9th intercostal space
    • Air: aim for 2/3rd the way up between CCJ and spine
    • Fluid: may need to aim closer to CCJ
    • Insert needle in front of rib (vessels and nerves lie caudal to ribs!!)
  3. Ultrasound-guidance helpful for effusions

(often you can make a patient feel a lot better by just tapping one side)

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9
Q

Thoracocentesis

A
  1. Insert needle bevel up
  2. W/ needles:
    • Once in chest, raise hand UP (allows needle to rest against body wall w/ bevel OUT - allows fluid to be pulled in)
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10
Q

Thoracocentesis: volume removed

A
  1. Save samples of effusion
    • Note total volume removed
    • EDTA tube: preserves cell morphology for cytology
    • Red top: various biochemical tests
    • Culture tubes (aerobic and anaerobic)
    • +/- PCV if hemorrhagic (if peripheral PCV is same as effusion PCV, indicates bleeding into pleural space - hemothorax)
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11
Q

Effusion Classification

A
  1. Transudate
    • Protein ~0.0 g/dL
    • TNCC < 2500/uL
  2. Modified transudate
    • Protein ~2.5 g/dL
    • TNCC ~2500 - 5000/uL
  3. Exudate
    • Protein > 5 g/dL
    • TNCC > 5000/uL
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12
Q

Pleural effusion: transudates

A

Transudates:
1. Low protein, low cellular pleural fluid
2. Usually caused by low oncotic pressure
- Hypoalbuminemia
DDx: Hepatopathy (decreased liver function), PLE, PLN
3. *Or increased hydrostatic pressure from early heart failure
- Over time the heart failure transudates turn into modified transudates

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13
Q

Pleural effusion: modified transudates

A

Modified transudates

  1. Transudates that have been “modified” by the addition of: cells, protein, and/or chyle
    • Right sided heart failure, pericardial disease
    • Neoplasia (lymphoma, mesothelioma, carcinoma, etc)
    • Chylothorax
    • Lung lobe torsion
    • Idiopathic
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14
Q

Pleural effusion: exudates

A

Exudates:

  1. High protein, high cellular effusions
  2. Predominant cell type depends on underlying cause
    • Infectious (bacterial, fungal)
    • Neoplasia
    • FIP
    • Chylothorax
    • Lung lobe torsion
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15
Q

Biochemical tests

A
  1. Triglycerides
    • Definitive dx of chylothorax: fluid TG > serum TG
      (chyle = fat and WBC’s)
  2. Glucose
    • Low in septic effusions
  3. pH
    • Low in septic effusions
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16
Q

Thoracic imaging

A
  1. Radiographs
    • Confirm pleural effusion (masks soft tissue lesions!)
      • sometimes you may want to do thoracocentesis, drain the fluid and repeat radiographs
    • May help determine etiology (cardiomegaly, mediastinal mass, lymphadenopathy)
  2. Thoracic ultrasound
    • Pleural fluid acoustic window
    • Pleural thickening, masses, abscess
  3. Thoracic CT
    • Neoplasia, abscesses, foreign body
17
Q

Pleural fluid and neoplasia

A

Neoplasia is a frequent cause of pleural effusion!*

  1. Tumors affecting any one of the following locations
    • Visceral/parietal pleura, lungs, mediastinum, LN/lymphatics
  2. Varied fluid types: modified transudate (or exudate), chylous
18
Q

Pleural fluid and neoplasia: Dx

A

Dx: identify cells on fluid cytology
- Most common w/ round cell neoplasia (lymphoma - they usually flake off the best)
- Absence of a dx on fluid cytology
- Imaging (ultrasound - thorax AND abdomen, CT)
NOTE: abdomen is easier to biopsy/aspirate than is the thorax
- +/- surgery for exploration and biopsy
- thoracoscopy
- thoracotomy

19
Q

Hemothorax

A
  1. Hemorrhage into the pleural space
  2. Causes
    • Trauma
    • Neoplasia
    • COAULOPATHY (rodenticide!!!)*
    • Vessel rupture
      • lung lobe torsion, heartworms, Spirocerca lupi (all not super common)
20
Q

Hemothorax: dx

A
  1. Effusion PCV roughly equals peripheral PCV
  2. Effusion should NOT clot (platelets and clotting factors get taken back up by pleural surfaces quite quickly!)
  3. Effusion contains:
    • Macrophages
    • NO platelets
21
Q

Hemothorax: tx

A
  1. Only tap if necessary to alleviate dyspnea
    • Body will absorb RBC’s
    • May make worse if coagulopathy present
  2. Assess coagulation status
    • PT and PTT
  3. Treatment depends on underlying cause
    • Vit K and blood products for rodenticide toxicity
    • Surgery may be indicated if bleeding mass

Small Animal Medicine (31 decks)

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