105 - Pleurisy Flashcards
Embryological origins of lungs
Epithelium
Embryological origins of pleura
Mesoderm
What is the pleural cavity
Potential space between visceral and parietal pleura. Only present in abnormalities.
What is empyema
Pus in pleural cavity. Results in development of scar tissue - pleural thickening
What is a pneumothorax
Air in pleura - causes a collapsed lung
What is a chylothorax
Lymph in pleura.
Rare - secondary to thoracic duct obstruction due to lymphoma.
Tumour in pleural cavity - what could it be?
Primary - mesothelioma
Secondary - metastatic, commonly carcinomas
What is pulmonary oedema
Fluid in lungs. Not the same as pleural effusion
Radiological signs of pneumothorax
Deviation of trachea away from affected side.
Collapsed lung - black space (will be hyper-resonant)
Check apex. Easily missed in this region
What is a sub pleural bleb?
Peripheral cyst on surface of lung filled with air. If pops - pneumothorax
How to treat pneumothorax
Insert a chest drain. End in sterile water to prevent air getting back into pleural cavity
Treatment of recurrent pneumothorax
Sterile talc to irritate pleura and cause to stick together.
Removal of lobe affected by pleural blebs.
What is Starling’s equillibrium
Fluid movement between intravascular and extravascular compartments is controlled by Starling forces.
Net fluid flow though a capillary wall (out of the blood) is controlled by:
- Hydrostatic pressure (arterial blood pressure) at the arteriole end of the capillary bed.
- Capillary permeability.
- Opposing osmotic pressure exerted by serum proteins and interstitial oncotic pressure (oncotic pressure = osmotic pressure exerted by proteins).
Reabsorption of interstitial fluid is controlled by:
- Plasma oncotic pressure – pulling pressure.
- Hydrostatic pressure in the interstitial space – tissue pressure.
- Fall in hydrostatic pressure at venous end of capillary.
Imbalance in Starling forces
Interstitial spaces expand
Pulmonary oedema occurs when
Lymphatic drainage capacity is exceeded
What is exudate?
Pleural effusion made of a protein rich cloudy fluid full of inflammatory cells. Occurs due to inflammation
What is transudate
Excess tissue fluid that leaks into the space between layers. A clear, protein poor fluid that usually arises in diseases that alter Starling equilibrium e.g. heart failure.
Colour of transudate and exudate
Transudate - straw coloured, clear.
Exudate - cloudy
Pleural effusion
Fluid in pleural cavities
Bilateral pleural effusions tend to be
Transudate
Unilateral pleural effusions tend to be
Exudate. Occur due to inflammation.
Investigations in pleural effusion
CXR
Microbial culture
Cytopathology
Pulmonary embolism
Wedge sharped infarct with involvement of visceral pleura. Blocks arterial blood to lung. Causes pleuritic pain. May have broken off a DVT
Pleuritic pain
Sharp, localised pain on deep inspiration
Radiological signs of pleural effusion
White, cloudy appearance on X-Ray.
Blunting of costodiaphragmatic angle.
Meniscus sign - curved lung base as filled with liquid.
Lung can collapse.
Trachea displaced away from affected side.
Use of ultrasound
Use to identify presence of pleural fluid and to guide diagnostic aspiration
Routine pleural aspirate investigations
CXR
Diagnostic aspiration under US
Check colour of liquid
Send samples for analysis
Further investigations for transudate pleural effusion
• U&Es – check kidney function.
• LFTs - check liver function
ECG – check heart function
Further investigations for exudate pleural effusion
- CT thorax
* Thoracoscopy if the pleural aspiration was non-diagnostic. Take another biopsy using an endoscope.
When would Light’s criteria be used - how would it be interpreted.
se when [protein] in aspirate is between 25-30g/L and cannot determine if transudate or exudate.
If any of the 3 conditions for exudate is met, consider exudate. 20% will be transudate but only 2% of cases diagnosed as transudate will be exudate.
Light’s criteria
Fluid is exudate if one of the following Light’s criteria is present:[1, 2, 3, 4]
Effusion protein/serum protein ratio greater than 0.5
Effusion lactate dehydrogenase (LDH)/serum LDH ratio greater than 0.6
Effusion LDH level greater than two-thirds the upper limit of the laboratory’s reference range of serum LDH
Indications for chest drain insertion in pneumothorax
- Persistent/recurrent pneumothorax after simple aspiration.
- Tension pneumothorax – initial relief with small bore cannula/needle but then will always need a chest drain.
- Ventilated patients with pneumothorax always need a chest drain as will become tension pneumothorax if not.
- Large, spontaneous secondary pneumothorax in pts >50yrs.
- Iatrogenic causes may require drainage.
- If traumatic pneumothorax
- Haemopneumothorax.
Indications for chest drain insertion in pleural effusions.
Pleural effusions – drain malignant pleural effusions, all pleural effusions in ventilated patients, empyema and complicated parapneumonic pleural effusion (bacterial infection).
Where to insert chest drain in pneumothorax/pleural effusion
Pneumothorax – aim to remove air, air rises so drain at apex.
Pleural effusion – aim to remove fluid, fluid sinks so drain at base.
How to fix blocked chest tube
Replace - never milk as can suck lung tissue into chest drain
When an you clamp a pneumothorax
ONLY under control of respiratory physician. Can convert to a tension pneumothorax
What is a floating rib
Rib broken in 2 places - free floating fragment
What is a flail chest
3 or more contiguous floating ribs. Marker for high impact chest trauma.
Significance of traumatic break to upper 3 ribs
Risk of damage to brachial plexus or subclavian vessels
Difference between pleural and pericardial rub
Sound very similar – pericardial rub with pericarditis if three audible components but if one or two audible components then could be either. Pleural rub can be heard during inspiration and expiration but a pericardial rub can be heard even when the patient holds their breath. Pleural rub is generally in lateral part of the chest wall while pericardial rubs are central.
Pneumothorax not pleural effusion if
Due to trauma
Hyper-resonant percussion tone
Pleural effusion not pneumothorax if
Due to underlying pathology
Stony-dull percussion tone
Can hear pleural friction rub
Non-productive cough
Trachea in tension pneumothorax
Deviates AWAY from affected side
Treat a tension pneumothorax
Chest drain
Treat a simple pneumothorax
Aspirate 16-18G cannula
Treated pleural effusion, now what?
Always look for underlying cause
Tracheal deviation in pleural effusion
Away from affected side
Tracheal deviation in collapsed lung
Towards affected side - least pressure
