Pleural Effusion Flashcards
Pleural Effusion
Pleural effusion= Accumulation of fluid in the pleural space. It can be classified as exudative or transudative, according to protein concentration.
Pleural Effusion: Classification
Pleural effusions can be broadly categorised into:
* Exudative – a high protein content (more than 30g/L)
* Transudative – a lower protein content (less than 30g/L)
In some cases (i.e. protein content 25-35g/L) Light’s criteria need to be applied.
Light’s criteria uses pleural fluid/serum protein or lactate dehydrogenase (LDH) to establish if a pleural fluid is an exudative effusion:
* Pleural fluid protein: serum protein ratio > 0.5
* Pleural fluid LDH / serum LDH > 0.6
* Pleural fluid LDH > 2/3 of the normal upper limit of the serum LDH
Malignancy-caused pleural effusions are generally serosanguinous exudates with low glucose and low pH and sometimes have elevated WBC counts. A mesothelioma may cause a heavily blood-stained pleural effusion. Pleural fluid cytology can be used to check for malignant cells, which can aid diagnosis but is only positive in roughly 50-60% of cases.
Pleural Effusion: Aetiology
Exudative causes are related to inflammation. The inflammation results in protein leaking out of the tissues into the pleural space (ex- meaning moving out of) due to increased capillary permeability.
The top causes are:
infection
* pneumonia (most common exudate cause)
* tuberculosis
* subphrenic abscess
connective tissue disease
* rheumatoid arthritis
* systemic lupus erythematosus
neoplasia
* lung cancer
* mesothelioma
* metastases
pancreatitis
pulmonary embolism
Dressler’s syndrome
yellow nail syndrome
Transudative causes relate to fluid moving across or shifting into the pleural space (trans- meaning moving across) due to increased hydrostatic pressure or decreased oncotic pressure. The top causes are:
* Congestive cardiac failure
* Hypoalbuminaemia
* Hypothyroidism
* Meigs syndrome (a triad of a benign ovarian tumour (usually a fibroma), pleural effusion and ascites. The pleural effusion and ascites resolve with the removal of the tumour).
Pleural Effusion: Presentation
Symptoms:
* shortness of breath
* non-productive cough
* chest pain
Examination findings:
* Dullness to percussion over the effusion
* Reduced breath sounds
* Tracheal deviation away from the effusion in very large effusions
Pleural Effusion:
Investigations
Imaging
* posterioranterior (PA) chest x-rays should be performed in all patients
* ultrasound is recommended: it increases the likelihood of successful pleural aspiration and is sensitive for detecting pleural fluid septations
* contrast CT is now increasingly performed to investigate the underlying cause, particularly for exudative effusions
* pleural aspiration/chest drain (if unstable) + ultrasound: fluid should be sent for pH, protein, lactate dehydrogenase (LDH), cytology and microbiology to establish underlying cause protein content, LDH, cell count, pH, glucose and microbiology testing.
Chest x-ray findings are:
* Blunting of the costophrenic angle
* Fluid in the lung fissures
* Larger effusions will have a meniscus (a curving upwards where it meets the chest wall and mediastinum)
* Tracheal and mediastinal deviation away from the effusion in very large effusions
Ultrasound and CT can detect smaller effusions than a chest x-ray, estimate the volume and identify potential causes.
pleural tap shows evidence of pleural infection (e.g. pH < 7.2 or turbid pleural fluid
Other characteristic pleural fluid findings:
low glucose: rheumatoid arthritis, tuberculosis
raised amylase: pancreatitis, oesophageal perforation
heavy blood staining: mesothelioma, pulmonary embolism, tuberculosis
All patients with a pleural effusion in association with sepsis or a pneumonic illness require diagnostic pleural fluid sampling
if the fluid is purulent or turbid/cloudy a chest tube should be placed to allow drainage
if the fluid is clear but the pH is less than 7.2 in patients with suspected pleural infection a chest tube should be placed
Pleural Effusions: Treatment
Diagnosing and treating the underlying cause is the mainstay of management.
* small effusions will resolve with treatment of the underlying cause
* More significant effusions often need aspiration or drainage.
Options for managing patients with recurrent pleural effusions include:
recurrent aspiration
pleurodesis
indwelling pleural catheter
drug management to alleviate symptoms e.g. opioids to relieve dyspnoea
Pleural Effusion: Complications - Empyema
Empyema= an infected pleural effusion. Suspect an empyema in a patient with improving pneumonia but a new or ongoing fever. Pleural aspiration shows pus, low pH, low glucose and high LDH. Empyema is treated with a chest drain and antibiotics.
British Thoracic Society (BTS) state that the following are the main indications for placing a chest tube in pleural infection:
* Patients with frankly purulent or turbid/cloudy pleural fluid on sampling should receive prompt pleural space chest tube drainage.
The presence of organisms identified by Gram stain and/or culture from a non-purulent pleural fluid sample indicates that pleural infection is established and should lead to prompt chest tube drainage.
Pleural fluid pH < 7.2 in patients with suspected pleural infection indicates a need for chest tube drainage.
immediate chest drain insertion as she is stable.
