The pleura Flashcards
Describe the normal pleura
Glistening, smooth, thin membrane
It covers the thoracic cavity and the lung
What is the outer layer of the pleural cavity called?
Parietal pleura
What is the inner layer of the pleural cavity called?
Visceral pleura
What is in between the parietal and visceral pleura?
Pleural fluid
Explain the pleural fluid
Straw coloured
0.26ml/kg/cavity
Filtration
Protein 1.5-3g/dl
Contains few cells - macrophages, lymphocytes and mesothelial cell
Describe the pleural pressure
Subatmospheric (negative)
-3 to -5cm of water
Gradient from apex to base
What is a pleural effusion?
Collection of fluid in the pleural space
There is an imbalance between production and absoption
What controls absorption?
Pleural lymphatics in the parietal pleura
What are the 2 types of effusion?
Transudate
Exudate
What is transudate effusion?
Non inflammatory and is due to filtration. Low protein content
What is exudate effusion?
Inflammatory, high protein content
Protein content: 3g/dl or more
What is lights criteria?
Light’s criteria are used to determine the nature of a pleural fluid sample, and narrow down the differential diagnosis of a pleural effusion.
A pleural fluid sample is most likely exudate if one or more of the criteria are met
What is the criteria in lights criteria?
Protein : Pleural Fluid / serum fluid ratio > 0.5
LDH : Pleural Fluid / serum fluid ratio > 0.6
Pleural fluid LDH > 2/3rd ULN serum LDH
What are some common causes of transudates?
Left ventricular failure
Liver cirrhosis (scarring of the liver caused by long term lung damage)
What are less common causes of transudates?
Hypoalbuminemia, peritoneal dialysis, hypothyroidism, nephrotic syndrome and mitral stenosis
What some common causes of exudates?
Malignancy (pulmonary or not)
Parapneumonic effusions
Empyema
TB
What are some less common causes of exudate?
Pulmonary embolism, connective tissue disease, benign asbestos pleural effusion, pancreatitis, post-myocardial infarction, post-coronary artery bypass graft and haemothorax
What investigations are used?
Ultrasound, CXR and CT thorax
What are the benefits for using ultrasounds?
More sensitive than CXR
Can mark site of aspiration and assess the pleura
Can do at patients bedside
Need someone trained to read the US
What are the benefits of using CXR?
Accessible and easy to interpret
Often the first test
Usually need 200 ml of fluid to show up
What are the benefits of using CT thorax?
Good for complex effusions
and visualising the pleura, vascular and mediastinal structures
How is the pleural fluid analysed?
Aspiration is simple and safe and can mark with US. Trained operator needed
Inspect the fluid for blood or pus…
PH measured by ABG machine
Biochemistry, microbiology and cytology
What PH suggests pus in the pleural fluid?
Under 7.2 may suggest pus
What is the management needed if PH is less than 7.2?
Pus or blood may need a chest drain
What is the management of transudate?
Treat the underlying cause and may not need CT imaging unless it does not resolve
What is the management of exudate?
Unless the cause is identified then will need further investigation like further imaging and/or pleural biopsy
What is a pneumothorax?
Collection of air in the pleural space
Air enters the pleural cavity an lung collapses
What is a primary spontaneous pneumothorax?
In absence of lung disease
Rupture of blebs in lungs and cause leak of air which compresses the lung
Is an abnormal accumulation of air
What is secondary pneumothorax?
There are existing lung problems that are known
What is a spontaneous traumatic pneumothorax?
Caused by an injury or blunt force
Ex. Broken ribs or knife stab
Causes a tear in lung so air enters the pleural cavity
What is iatrogenic pneumothorax?
Acquired in hospital
A result of biopsy for diagnosis
Patient can be on ventilation and air used causes pressure or pacemaker
What is tension pneumothorax?
Air in the pleural cavity builds up in pressure and pushes central structures (trachea) and pushes the opposite lung
This causes pressure on the heart and patient can go into cardio-resp. arrest
What are the presentations of a spontaneous pneumothorax?
Sudden event
Chest pain or breathlessness
Usually happens in tall thin young males - uncommon underlying lung disease
What are the clinical examination presentations for spontaneous pneumothorax?
Breathing fast - tachypnoeic, hypoxic, reduced chest wall movements and reduced/ no breath sounds
Not uncommon for exam to be normal
What is used to diagnose a patient with a pneumothorax?
CXR, US and CT thorax
What is taken into account when managing a pneumothorax?
Size
Effect on the patient
Trained operator and staff needed for the aftercare
What is the management for pneumothorax?
Observe - if small and patient well
Aspiration - over 2 cm in size and patient well
Chest drain insertion
Surgery - recurrent events or resolving
Where is the safe triangle used in pleural aspiration/ drain?
2nd intercostal space midclavicular line
Lateral edge of pectoris major, base of axilla, lateral edge of latissimus dorsi and 5th intercostal edge
What are the types of pleural tumours?
Benign - rare
Malignant pleural effusions are common - poor outcome
Primary malignancy - mesothelioma is the most common
Describe a Mesothelioma
Is rare and aggressive
Primary malignancy - caused spontaneously by mutation, common with asbestos
Inhaled asbestos fibres reach pleura and cause inflammation which provokes tumour formation
Long latent period
What are the clinical presentation of mesothelioma?
Breathlessness, chest pain, weight loss, clubbing and signs of pleural effusion
Possible palpable neck nodes
How would you diagnose pleural tumours with CXR?
Look for pleural effusion and pleural based mass
How can you diagnose pleural tumours?
CT thorax and biopsy - needed to stage. Need to show invasion of tissues
Thoroscopy - directly visualise pleura and samples, spray lining to stop fluid reaccumulating
What can be found when diagnosing pleural tumours?
Thickened pleura, pleural nodules or masses, pleural plaques, an effusion and soft tissue infiltration
What is the management of pleural tumours?
Treatment options are limited and palliative
Treating the effusion
Chemo for fit patients
Recruitment to trails via MDTs
Palliative surgery in select pateints
