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Flashcards in Pleural space Deck (21):

Pleural anatomy

  • Parietal
    • Covers the entire inner surface of the thorax
    • Divided into 3 parts:
      • Costal
      • Diaphragmatic
      • Mediastinal
  • Visceral
    • Covers lung parenchyma
  • Left and right pleural sacs are closed
  • Pleural space is a potential space
  • Contains some fluid that lubricates lung and thoracic body wall
  • Space is in the area between
    • Individual lung lobes
    • Lung lobes and body wall


Radiographic anatomy

  • Normal pleura is usually not visible
    • Silhouettes with adjacent soft tissue
    • Too thin to absorb enough x-rays to be detected
    • Except if radiographed tangentially
  • Occasionally, thin soft-tissue/fluid opaque pleural lines are noted between lobes
    • Pleura may be thick
    • Pleura may be in line w/ beam and absorb enough x-rays
    • Cannot determine exact reason but slight pleural thickening is usually of little significance
  • Location of pleural fissures, the regions between lung lobes, is an important radiographic-anatomic feature
  • Pleural fissure lines will vary with
    • Positioning or recumbency of the patient
    • Amount of fluid present
    • Tangential alignment of normal pleura w/ x-ray beam


Pleural disease

Clinical signs?


Thoracic auscultation?

Resp. pattern?

  • Clinical signs for pleural fluid include:
    • Dyspnea, thoracic cavity distention, dyssynchronous breathing
  • In cats, breathing is slower and more deliberate than in dogs
  • Thoracic auscultation reveals muffled lung sounds over the affected regions
  • The resp. pattern is the same whether air, fluid, or abdominal contents are in the pleural space


What are the 3 main categories of pleural disease?

  • Pleural effusion
    • Fluid in pleural space
      • Cannot be distinguished
  • Pneumothorax
    • Gas in pleural space
      • Enters from outside, mediastinum, or lung
  • Diaphragmatic hernias


Pleural effusion: clinical significance

  • Primary pleural disease is rare
    • Often a sign of disorder elsewhere
  • ALWAYS IMPORTANT--requires workup
  • If detected with peritoneal effusion: indicates severe disease with a poor prognosis


Pleural effusion: DDx

  • CHF
  • Malignancy
  • Pyothorax
  • Pneumonia
  • Trauma
  • Coagulopathy
  • Rib tumor
  • Diaphragmatic hernia
  • Chylothorax
  • Mediastinitis


Pleural effusion: what do radiographic signs depend on?

  • Volume of fluid
  • Patient positioning
  • Distribution of fluid
  • Free vs. loculated fluid


Free pleural effusion (11 thingz)

  • Radiograph signs are the same for dif. types of fluids
  • Gravity
  • Lung compliance
  • Appearance will be different in dif. views
  • Wide interlobular fissures
  • Soft tissue opacity between lungs and thoracic wall
  • Retraction of lungs from thoracic wall
  • "Scalloping" of lung margins
  • Silhouetting of heart in DV view
  • Silhouetting of diaphragm
  • Soft tissue opacity dorsal to sternum


Pleural effusion: wide interlobar fissures

  • Thickness and # depend on amount of fluid present and position of the patient
  • Min of 100mL of fluid must be present to detect fissure lines in MBD
  • X-ray must strike the intralobar tangentially
  • In cases of small amounts of fluid, interlobar fissures are more likely to be detected on VD and laterals


Important positioning concept w/ pleural effusions

  • Gravity is in play
  • Fluid will migrate to dependent regions


Pleural effusions: restrictive pleuritis

  • Signs of pleural fusion
  • Severely rounded lung lobe margins due to changed lung compliance
  • Lung lobes do not return to normal space following thoracocentesis


Pleural effusions: atypical or asymmetrical distributions

  • Usually uniform distribution
  • If non-uniform displacement, consider:
    • Lung pathology altering compliance of the lung
    • Mass in thoracic wall
    • Loculated fluid
  • Pyothorax is a common cause of unilateral distributions of pleural fluid


Pleural effusion: other tests

  • Horizontal-beam radiograph
  • Other view to look for inciting lesions
    • If large amounts of fluid are present remove before continuing further imaging studies
  • Ultrasound +/- FNA
  • CT


Pitfalls of pleural effusion

  • Thickened pleura
  • Mineralized costal cartilage
  • Thoracic wall deformity


Pneumothorax: classifications

  • Open
    • Free communication between pleural space and environment
  • Closed
    • Air leaks into pleural space via lung, bronchi, trachea, esophagus, or mediastinum
  • Tension
    • Valve, continuous influx of air upon inspiration that does not return to lung on expiration
    • Pleural pressure > atmospheric pressure
  • Normotensive
    • Pleural pressure = atmospheric pressure


Pneumothorax: clinical significance

  • Traumatic is the most frequent type and result in a normotensive closed
    • Young, males predisposed
  • May be open due to gunshot wound or penetrating foreign body
  • Spontaneous type occurs more frequently in deep-chested breeds
  • Small pneumothorax w/o clinical signs will not require treatment
  • Pneumothorax due to lung disease will likely require intervention
  • Usually occurs bilaterally
  • Air moves easily between right and left sides
  • Unilateral can occur for similar reasons as unilateral pleural effusions


Pneumothorax: DDx

  • Trauma
  • Lung rupture
  • Ruptured pulmonary bulla
  • Chest wall rent
  • Pulmonary emphysema
  • Extension of a pneumomediastinum
  • Rupture of a cavitary lung mass
  • Iatrogenic barotrauma


Pneumothorax: radiographic signs

  • Gas opacity between lungs and thoracic wall
  • Pulmonary blood vessels do not continue to thoracic wall
  • Retraction of lungs from thoracic wall
  • Lung is small and has increased opacity
  • Appearance of dorsal displacement of heart on lateral view ("loss of sternal contact")
  • Best seen on lateral view
  • Easier seen on DV versus VD


Tension pneumothorax: radiographic signs

  • Greater degree of lung collapse
  • Tenting of diaphragm
  • "Barrel-chested"


Pitfalls of pneumothorax

  • Skin folds
    • Soft tissue bands extend beyond pulmonary limits and into chest wall
    • May need hot light to see pulmonary vessels
  • Breed variations
    • Chondrodystrophic breeds
    • Chest conformation
  • Miscellaneous
    • Small cardiac silhouette
    • Hyperinflated lungs


Pneumothorax: other tests

  • Horizontal beam radiography
    • Lateral recumbency
  • CT
    • Test of choice to find bullae
    • Greater sensitivity than rads