Pleural Effusion
last authored: Sept 2010, David LaPierre
last reviewed:
Introduction
A pleural effusion is the accumulation of fluid in the pleural space, which normally contains no more than 15 ml of serous fluid. Effusions can be asymptomatic, though large collections can cause shortness of breath, cough, and pain, as well as various physical signs and evidence on imaging.
The Case of Shirley Round
Shirley is a 68 year-old woman admitted for control of new-onset atrial fibrillation. During her physical exam, decreased breath sounds are evident on the left, coupled with dullness to percussion.
- Q: what is the differential diagnosis of pleural effusion?
- Q: what further history and physical exam would you like?
- Q: what imaging and lab investigations do you order?
Causes and Risk Factors
Increased pleural fluid can accumulate due to a range of processes. These include: increased fluid production, with normal capillaries (transudate); abnormal capilary permeability (exudate); decreased lymphatic drainage (exudate); pus collection (empyema); and blood collection (hemothorax).
Transudative (more often systemic disease)
- congestive heart failure, leading to fluid overload and increased hydrostatic pressure
- nephrotic syndrome
- liver disease, leading to decreased osmotic pressure
- peritoneal dialysis
- myxedema
- constrictive pericarditis
- SVC obstruction
- pulmonary embolism
Exudative (more likely local disease)
- infection/inflammation (pneumonia, turberculosis, abscess)
- cancer (lung, breast)
- pulmonary embolus and lung infarct
- atelectasis, leading to increased intra-pleural negative pressure
- abdominal inflammation
- subphrenic abscess
- pancreatitis
- mediastinal involvement of cancer or other causes of decreased lymphatic drainage
- pulmonary embolism
- hypoalbuminemia
- autoimmune causes: SLE, RA
- asbestosis
- Dressler's syndrome - antimyocardial antibody syndrome
- Meig's
- sarcoidosis
- radiotherapy
Pathophysiology
Signs and Symptoms
- history
- physical exam
History
Patients can complain of:
- shortness of breath
- cough
- hemoptysis
- chest pain
Other symptoms that should be inquired into:
- weight loss
- fever
Past medical history should be specificially assessed for:
- pneumonia
- CHF
- thromboembolic disease
- connective issue disease
- smoking
Physical Exam
Vitals.
Respiratory exam can reveal:
- dullness on percussion
- decreased or absent breath sounds
- decreased or absent tactile fremitus and transmitted voice sounds, though may be accentuated at top of a large effusion
- shift of trachea away from side of effusion
- crackles may be evident if due to CHF or other causes of pulmonary edema
Other important findings:
- cardiac exam
- peripheral edema
- calf swelling (DVT)
- clubbing
- cyanosis
- Horner's syndrome
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Blood tests should include:
- CBC
- electrolytes
- renal function tests
- LDH
- total protein
- AST, ALT
- bilirubin
- INR, PTT
Fluid aspiration, followed by microscopic analysis of the fluid, is critical. Tests include:
- cell count and differential, gram stain, C&S, glucose, albumin, LDH, AFB)
exudate, rather than transudate, reveals:
- fluid/serum albumin >0.5
- fluid/serum LDH >0.6
- fluid LDH >2/3 upper limit of normal serum level
acidosis (pH <7.2): pneumonia, TB, malignancy, connective tissue disease, hemothorax, exophageal rupture, paragonimiasis
glucose <3.3: pneumonia, TB, malignancy, Churg-Strauss, hemothorax, pneumothorax
Other tests can include biopsy.
Diagnostic Imaging
Chest X rays show increased pleural space and rounding of the lung-diaphragm margin.
CT chest may be done to assess malignancy or other diagnoses.
Differential Diagnosis
Other fluids that can collect include pus (empyema - suppurative infection), blood (trauma, ruptured aneurysm) or lymph (tumour blockage of lymphatics).
Treatments
Treat the underlying cause.
Symptom control should include:
- oxygen
- dieuresis
- drainage (thoracentesis, pig tail catheter, pleurex catheter, chest tube)
For palliative measures, pleurodesis can be done by injecting inflammatory chemical to glue the pleural linings together. This prevents fluid accumulation in many cases.
Consequences and Course
Effusion with pneumonia usuaually resolves with antibiotic treatment.
Resources and References
www.chestjournal.org/content/135/1/201.full
Topic Development
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