Week 1 - Pleural Space and Mediastinum Disease Flashcards
What is the pleural space?
Two membranes that surround the lungs that contain fluid.
A space between the two pleura which helps the lungs move and expand to fill with air.
How much fluid and what sort of pressure should there be in the pleural space?
0.1 ml/kg of fluid.
Negative pressure - acts as a suction to keep the lungs from collapsing.
What is the mediastinum and what does it contain?
The space between the pleural sac.
Contains blood vessels, nerves, oesophagus, trachea, heart, lymphatic vessels, thymus.
Why can’t patients breathe with pleural disease?
There is a loss of thoracic capacity = less room in the chest for the lungs to expand.
Severity depends on quantity of fluids, air or size of mass.
Known as restrictive disease
How to patients present with pleural space disease?
Restrictive breathing: short, shallow breathes
Tachypnea
Open mouth breathing
Dyspnoea
Orthopnoea
Cyanosis
Muffled heart sounds
Acute or chronic
How do you investigate pleural space disease?
Clinical exam
Percussion
Imagine (FAST, TFAST or radiography)
What can cause the loss of thoracic capacity?
Pleural effusion
Pneumothorax
Neoplasia
Ruptured diaphragm
Abdominal abnormality
Gross cardiomegaly
What is pleural effusion and what causes it?
Fluid in the pleural space (more than normal)
Causes:
- Decreased absorption (from parietal lymphatic vessels)
- Increased production (from parietal pleural vessels)
What are the three types of fluid that causes pleural effusion?
- Transudate
- Modified transudate
- Exudate (with cells)
If a suspected pleural effusion presented, what steps would you take?
- Oxygen supplementation
- Thoracic ultrasound (often too severely dyspneic to radiograph)
- Thoraconcetesis (sample fluid, diagnostic (cytology, cell count, protein, bacterial culture), relief from clinical signs, stabilise)
How is a thoracoentesis performed?
- Aspetic
- Local anaesthesia rarely needed
- Clip area
- Surgically prep skin
- +/- ultrasound guided
- Butterfly needle or catheter into ICS 6-8
- Insert chest drain fro effusions that quickly reappear or that need lavaging (pus present)
What is a transudate and what are the characteristics?
Low protein fluid -> caused by hypoalbuminaemia (low oncotic pressure) -> lead to a leakage of fluid out from the vascular compartment.
- Clear
- Protein <2g/l
- SG <1.018 (low)
- Few cells (if any)
What conditions can cause transudate?
Low protein
- Liver failure (failure of synthesis)
- Protein loosing enteropahty
- Protein loosing nephropahty
- Haemorrhage
- Starvation
- Hyperglobulinaemia (high globulin = low albumin)
What is a modified transudate and what are the characteristics?
High protein fluid -> caused by increased hydrostatic pressure
- Clear
- Protein 2-5 g/dL
- Few cells (if any)
What conditions can cause a modified transudate?
Common - secondary to right sided heart failure
Diaphragmatic hernia (no negative pressure)
Damage to pleural vessels which leak fluid
- Lung lobe torsion
- Neoplasia
What is a exudate and what are the characteristics?
Filled with cells, higher protein and tends to be coloured.
- Coloured
- Protein >2.5 g/dL
- Lots of cells
What 4 conditions can cause an exudate?
- Blood (haemothorax)
- Chyle (chylothorax)
- Septic exudate (pyothorax)
- Non septic exudate
What characterises and causes a haemothorax?
Contains RBCs
Red colour
Trauma
Coagulopathy
Neoplasia
Lung lobe torsion
What characterises and causes a chylothorax?
Small lymphocytes
Lipid looking
Disruption to the thoracic chyle duct -> lung lobe torsion, trauma, tumour pressing on duct.
What characterises and causes a pyothorax?
Bacterial and inflammatory leukocytes
Infection
Foreign body
Ruptured pulmonary abscess or mass
What characterises and causes a non-septic exudate?
Inflammatory cells without bacterial cells visualised.
Feline infectious peritonitis (FIP_
Neoplasia
Chronic chylothorax/torsion -> develop inflammatory cells over time.
Fungal infection (rare)
What is a pneumothorax?
Air around the lung -> compressed the lung.
There is a loss of negative pressure in the pleural space -> lung collapses and struggles to inflate.
How do you treat the following that cause pleural effusion:
- Heart failure
- Pericardial effusion
- Pyothorax
- Chylothorax
- Heart failure -> treat the failure
- Pericardial effusion -> drain effusion or PTS
- Pyothorax -> Antibiotics (culture but start on broad while wait for results), lavage, long term treatment with hospitalisation.
- Chylothorax -> diet/surgery and treat heart failure
What can cause a pneumothorax?
Rupture of airway/lung tissue (tension pneumothorax) -> neoplasia or trauma
Perforation of oesophagus
Thoracic trauma
Iatrogenic
Gas producing bacterial infection in the pleural space
How do you diagnose a pneumothorax?
Auscultation
- Dorsally = dull sounds
- Ventrally = increased sounds
Percussion = sounds like a drum
T-FAST = loss of glide sign
Blood gas and pulse oximetry
How do you treat a pneumothorax?
Oxygenate
Drain (chest drain or one way valve)
Locate the cause (could be spontaneous)
Cage rest
What is this pleural space neoplasia and how is it diagnosed and treated?
Mesothelioma
Affects lining of pleural sacs and pericardial sac
CT for best diagnosis
Cytology
Chemotherapy possible but poor prognosis
What neoplasia can be found in pleural space?
Mesothelioma
Rib tumours that can invade the pleural space:
- Osteosarcoma
- Chondrosarcoma
What types of disease can affect the mediastinum and what do they do?
Trauma
Infection/inflammation
Neoplasia
Generally causes pressure on the structures in the mediastinum.
If the following where affected in the mediastina, what signs would there be?
- Lungs
- Oepshagus
- Vena cava
- Heart
- Sympathetic pathway to orbit
- Lungs = respiratory signs
- Oepshagus = regurgitation
- Vena cava = oedema in head and forelimbs
- Heart = Right sided heart failure
- Sympathetic pathway to orbit = Horner’s syndrome
What diagnostics can be done for mediastinum investigations?
Radiography
- Check tracheal position
- Check lung lobe boarders
Ultrasound - less useful as structures need to be big enough to visualise
CT = most useful!
Sampling = not 1st opinion
What are three mediastinum neoplasia’s?
- Lymphoma (common in young cats)
- Thymoma (young or older dogs)
- Thyroid carcinoma (rare)
What are the signs, diagnosis and treatment for lymphoma?
Young cats or dogs with multi centric lymphoma
Signs
- none
- non-compressible anterior mediastinum
- Respiratory signs
Diagnosis:
- Radiograph, CT
- Cytology
- FeLV status (predisposes)
Treatment
- Chemotherapy (can go into remission)
What are the signs, diagnosis and treatment for thymoma?
Rare = young and older dogs
Benign (but can keep growing)
Malignant (metastases rare)
Signs
- Similar to lymphoma
- None
- Mild respiratory signs
- Megaoesphagus
- Paraneoplastic syndrome (parathyroid hormone related peptide -> hypercalcemia)
Diagnosis:
- Radiograph, CT
- Cytology
Treatment
- Chemotherapy
- Surgical removal
- Megaoesphagus = prognosis poor
What are the signs, diagnosis and treatment for thyroid carcinoma?
Cats that are unresponsive to hyperthyroid treatment
Dogs = mass signs
Treat with radioactive iodine.
