Pleural Space and Mediastinal Disease Flashcards
How do patients with pleural space or mediastinal disease present?
- Restrictive breathing pattern: short, shallow breaths
- Tachypnoea
- Open mouth breathing
- Dyspnoea, respiratory distress
- Orthopnoea (elbow abduction, sternal recumbency)
- Cyanosis
- Muffled heart sounds
- May be acute or chronic
How do we start to investigate pleural space or mediastinal diseases?
- Clinical examination - cardiorespiratory examination and observation
- Percussion
- Imaging - FAST scan – TFAST or radiography
- Next depends on what we find – thoracocentesis, chest drain, further imaging, surgery…
What are the 6 possible causes of loss of thoracic capacity?
- pleural effusion
- pneumothorax
- neoplasia
- ruptured diaphragm
- abdominal abnormality
- gross cardiomegaly
What immediate steps should be taken in a patient with suspected pleural effusion?
- oxygen supplementation
- thoracic ultrasound
- thoracocentesis
What are the steps to a thoracocentesis?
- Local anaesthetic rarely needed unless large bore catheter
- Clip area – if possible use quiet clippers (minimal stress esp. cats)
- Quickly surgically prepare skin as best as possible
- Can perform ultrasound guided
- Butterfly needle or catheter at ICS 6-8
A chest drain may need to be placed for effusions that quickly reform or patients that need lavage e.g. pyothorax
What are the 3 possible fluid types in a thoracocentesis?
- transudate
- modified transudate
- exudate
What are the characteristics of transudate? What are possible causes?
- Clear (no colour)
- Protein <2g/L
- SG <1.018
- Few cells (if any)
Caused by hypoalbuminaemia (low oncotic pressure)
Liver failure – failure of synthesis
Protein-losing enteropathy
Protein-losing nephropathy
Haemorrhage or external losses in exudate (pus)
Starvation/malnutrition
Hyperglobulinaemia (decreases albumin production)
What are the characteristics of modified transudate? What is it caused by?
- Clear (no colour)
- Protein 2-5 g/dL
- Few cells (if any)
Caused by increased hydrostatic pressure
Secondary to right sided heart failure caused by heart disease or pericardial effusion (more on this next week!)
Diaphragmatic hernia
Lung lobe torsion
Neoplasia
What are the characteristics of exudate? What are the different types and what are they caused by?
- Coloured
- Protein >2.5 g/dL
- Lots of cells
- Blood (haemothorax) – contains RBCs, red -> trauma, coagulopathy, neoplasia, lung lobe torsion
- Chyle (chylothorax) – small lymphocytes and very lipid looking – disruption of the thoracic chyle duct
- Septic exudate (pyothorax) – bacterial and inflammatory leukocytes -> infection, foreign body, ruptured pulomary abscess or mass
- Non-septic exudate – inflammatory cells without bacterial visualised -> FIP, neoplasia, chronic chylothorax/torsion, fungal infection
What can cause a pneumothorax? How is it diagnosed? How is it treated?
Cause
- Rupture of airway/lung tissue
- Trauma
- Neoplasia
- Perforation of oesophagus
- Thoracic trauma – wound
- Iatrogenic
- Gas-producing bacterial infection in pleural space
Diagnosis
- Auscultation – dull lung sounds dorsally, increased sounds ventrally (air rises)
- Percussion – sounds like a drum
Thorasic radiography if the patient is stable
- T-fast – loss of glide sign
- Blood gases and pulse oximetry – assesses severity
Treatment
- Oxygenate
- Drain – chest drain or one way valve (Heimlich valve)
- Locate the cause (could be spontaneous!)
- 90% can recover with strict cage rest if cause identified and treated
What sign is characteristic of a mesothelioma? How do we diagnose it? How is it treated?
Sign
Causes large volumes of effusion
Diagnosis
CT best for diagnosis, cytology sent off to clinical pathologist
Treatment
Chemotherapy possible but very poor prognosis
What types of disease can be found in the mediastinum?
- Trauma (same as pleural space)
- Infection/inflammation -> possible foreign body
- Neoplasia
Disease generally causes pressure on structures in the mediastinum – acts as space-occupying lesion
How is mediastinal disease investigated?
- radiography
- ultrasound
- CT - most useful
- sampling
What are the signs of lymphoma? How is diagnosis acquired? How is it treated?
Signs –
can be none, non compressable anterior mediastinum, can have respiratory signs e.g. tachypnoea, dull heart sounds, pleural effusion
Diagnosis –
radiography, cytology on effusion, CT, check FeLV status, send off cytology for confirmation
Treatment –
chemotherapy is an option, can go into remission
What are the signs of thymoma? How is diagnosis acquired? How is it treated?
Signs –
can be none, mild respiratory signs, can present in respiratory distress with common mediastinal disease signs
Diagnosis –
radiography, CT, cytology (send off)
Treatment –
possible surgical removal, chemotherapy if required. Prognosis excellent if full removal. If has MG, it remains even after removal therefore prognosis poor.
