Diseases of the Pleura Flashcards
Which respiratory muscles are important in inspiration?
Diaphragm
External intercostals
(SCM and scalenes as acccessories)
Which respiratory muscles are important in expiration?
Normally none (Internal intercostals and abdominal muscles as accessories)
What mechanisms might underlie a pleural effusion? Give specific examples of causes of each
Starling forces:
Increased hydrostatic pressure (HF)
Increased capillary permeability (inflammation, malignancy)
Decreased oncotic pressure (liver or renal failure)
Impaired lymphatic drainage (infiltration by tumour, injury, inflammation)
What should be measured when sampling a pleural effusion to assist diagnosis?
Protein Glucose LDH pH Cytology MCS
What Ix can be ordered to evaluate a pleural effusion?
Biochemistry, cytology, MCS on sample if indicated
Imaging: CXR, US, CT chest
Bronchoscopy (not routine; doesn’t get into pleural space, use if concerned about underlying lung disease)
Thoracoscopy (VAT; may be indicated if complicated or cause unclear)
List some common symptoms of pleural disease
Pleuritic chest pain
SOB
Cough
Pleuritic chest pain DDx
PE
Pneumothorax
Pneumonia
MSK pain (including rib #)
Signs of air in the pleural space
Decreased chest expansion
Hyper-resonant percussion
Decreased breath sounds and vocal resonance
Signs of fluid/solid tissue in pleural space
Decreased chest expansion
Dullness to percussion (“stony dullness”)
Decreased breath sounds and vocal resonance
DDx bilateral pleural effusion
Increased hydrostatic pressure: HF, fluid overload
Increased capillary permeability: inflammation, malignancy
Decreased oncotic pressure: nephrotic syndrome, liver disease
Impaired lymphatic drainage: malignancy
DDx unilateral pleural effusion
Increased hydrostatic pressure: HF (less common)
Increased capillary permeability: infection, inflammation (post-PE), malignancy (primary)
Impaired lymphatic drainage: malignancy
3 risk factors for spontaneous pneumothorax
Smoking
Family Hx
Marfan’s syndrome
What are the 3 causes of pneumothoraces?
Spontaneous
Trauma
Underlying lung disease
How does underlying lung disease contribute to pneumothorax?
At risk of cysts or bullae which may burst, causing a pneumothorax
What are pleural plaques?
Areas of fibrous thickening on the pleura or diaphragm
What are the causes of pleural plaques?
Asbestos exposure
Previous empyema or haemothorax
List 6 asbestos-related lung diseases
Pleural plaques Pleural thickening Pleural effusions Pulmonary fibrosis (asbestosis) Mesothelioma Bronchogenic lung carcinoma
HF findings on CXR
Alveolar oedema Kerley B lines Cardiomegaly Dilated upper lobe vessels (diversion) Effusion
What does the protein content of a pleural effusion indicate?
High: likely exudate
Low: likely transudate
What does the glucose content of a pleural effusion indicate?
Low: infection or malignancy
What does the LDH content of a pleural effusion indicate?
High: likely exudate
Low: likely transudate
What does the pH of a pleural effusion indicate?
Low: infection or malignancy
What results on biochemical analysis strongly indicate that a pleural effusion is the result of an infection or malignancy?
Low glucose
Low pH
Common causes of an exudative pleural effusion
LOCAL CAUSE
Cardiac: pericarditis
Vascular: PE
Respiratory: haemothorax, chylothorax (due to disruption or obstruction of thoracic duct)
Abdominal: subphrenic abscess
Inflammatory: infection (pneumonia, pleuritis, empyema), malignancy (breast, lung, pleura)
Immunologic: RA, SLE
