Disease of the Pleura and Mediastinum Flashcards
what are the pleural membranes and what is within them?
single layer mesothelial cells
fat, elastin, lymphatics, vessels
what is in the mediastinum?
thymus
lymph nodes
esophagus
large thoracic vessels
heart
what species has a complete mediastinum and what is it?
humans, ruminants, swine
thick fascia completely separates the two pleural cavities
what species has a fenestrated or incomplete mediastinum and what is it?
horses
very thin fascia that can be easily ruptured by changes in intra-thoracic pressure
what are some causes of pleural effusion?
increased hydrostatic pressure in the microvascular circulation
decreased oncotic pressure
changes in microvascular permeability
impaired lymphatic drainage
what caused pleural transudate?
imbalance in hydrostatic and oncotic pressures
what causes pleural exudation?
pleural inflammation and impaired lymphatic drainage of protein and fluid
what are the non-inflammatory pleural effusions?
hydrothorax
hemothorax
chylothorax
what are the inflammatory pleural effusions?
serous or serofibrinous pleuritis
pyothorax or empyema
hemorrhagic pleuritis
when is a hemothorax usually seen?
thoracic trauma or surgery
can occur with coagulation defect
erosion vascular wall due to neoplasia or aneurysm
when is chylothorax seen?
traumatic or surgical duct rupture
less commonly neoplasia with thoracic duct obstruction, dilation, rupture
idiopathic in some, especially afgans and borzois
what do serous or serofibrinous pleuritis describe?
progressively more inflammatory exudates with accumulation of protein, inflammatory cells, and finally fibrin within pleural fluid
when does a pyothorax most commonly occur in companion animals?
penetrating foreign bodies or bite wounds
when does a pyothorax occur in a horse?
complication primary pneumonia or pulmonary abscess
what bacteria most commonly causes pleuropneumonia in horses?
Streptococcus equi subspecies zooepidemicus
what is pleuropneumonia from?
devastating complication of pneumonia or pulmonary abscesses
what are some risk factors of pleuropneumonia in horses?
long distance transportation
prior viral respiratory infection
exercise
what are the clinical signs of a pneumothorax?
pain
dyspnea
what is a flail chest?
2 rib fractures causing unstable segment of thoracic wall
moves in when breathe in and out when breathe out
what are primary pleural tumors?
mesotheliomas arising for either visceral or parietal pleura
mesenchymal or epithelial
what does pleural effusion cause?
restrictive disease pattern
V/Q inequality
reduced lung volumes
atelectatic lobes
how do you tap a chest so that you do not cause a pneumothorax?
offset skin stab incision and site of parietal pleura
is mediastinal disease usually primary?
no
usually sequela of systemic, thoracic, or cervical disorders
what are some common entities of mediastinal space-occupying masses?
lipoma
abscesses
lymphoma
granuloma
why can a pneumomediastinum lead to subcutaneous emphysema?
mediastinal space potentially communicates with the subcutaneous space via fascial planes
what is commonly associated with a hydrothorax?
cardiac disease
decreased oncotic pressure
what is commonly associated with a hemothorax?
trauma
rupture of large vessels
what is commonly associated with hemorrhagic pleuritis?
penetrating foreign body
neoplasia
what might non-fatal leakage of a smaller volume of blood in a hemothorax lead to?
development of pleural adhesions
what clinical signs are associated with pyothorax?
pain
dyspnea
respiratory distress
fever
signs of systemic infection
what is fibrinous pleuritis?
inflammation and thickening of the pleural membranes without effusion
what should be performed when pleural fluid volume increases?
culture and cytologic examination for neoplastic cells
when can a pneumomediastinum occur?
gas migration from deep neck wounds
esophageal or tracheal rupture
sequela of transtracheal aspirate
bronchial rupture
what are sequelae of pneumomediastinum?
generalized subcutaneous emphysema
accumulation of air along aorta or in retroperitoneal space
can a pneumothorax progress to a pneumomediastinum?
unlikely
