Pleural effusion in critically ill patients and intensive care setting

Table 1 Causes of transudative and exudative pleural effusions

Causes of transudative pleural fluid	Causes of exudative pleural fluid
Increased hydrostatic pressure: Congestive heart failure; constrictive pericarditis; pericardial effusion; massive pulmonary embolism; constrictive cardiomyopathy; pulmonary veno-occlusive disease	Infections: Parapneumonic effusion; complication of lung abscess; acquired immune deficiency syndrome; tuberculosis; fungal and actinomycotic disease; hantavirus syndrome; subphrenic abscess; hepatic amoebiasis
Reduced capillary oncotic pressure: Liver cirrhosis (hepatic hydrothorax); nephrotic syndrome; protein-losing enteropathy; malnutrition; small bowel disease	Neoplasm: Mesothelioma; metastasis; lymphoma; Meigs syndrome; rare tumors such as pleural sarcoma
Transmission from peritoneum: All causes of ascites; peritoneal dialysis; liver transplantation; ventriculoperitoneal shunt	Connective tissue diseases and immune disorders: Rheumatoid disease; systemic lupus erythematosus; post-myocardial infarction/cardiotomy syndrome; churg-Strauss syndrome; Wegener’s granulomatosis; rheumatic fever; Behcet syndrome; lymphangioleiomyomatosis
Increased capillary permeability: Small pulmonary emboli; myxoedema
Obstructed lung lymphatics: Lung transplantation	Abdominal diseases: Pancreatitis and pancreatic-pleural fistula. uraemia; other causes of peritoneal exudates
Others: Urinothorax; cerebrospinal fluid leakage into the pleura; trapped lung; central venous catheter migration	Others: Pulmonary embolism, sarcoidosis, drug reactions, radiation exposure, asbestos exposure, recurrent polyserositis, yellow nails syndrome, oesophageal rupture, superior vena cava syndrome, endometriosis, amyloidosis, extra-medullary hematopoiesis

Table 2 Criteria for differentiation between exudative and transudative pleural effusion

Light’s criteria	Pleural fluid only dependent criteria
Pleural fluid is considered exudate if Pleural fluid/serum protein > 0.5, pleural fluid/serum LDH > 0.6, or pleural fluid LDH > two-thirds of upper limits of the laboratory’s normal serum LDH	Pleural fluid is considered exudate if Pleural fluid protein ≥ 3 gm/dL, or pleural fluid cholesterol > 45 mg/dL, or pleural fluid LDH > 0.45 times the upper limit of the laboratory’s normal serum LDH

LDH: Lactate dehydrogenase.

Table 3 Some important pleural fluid analysis parameters and their relations to diagnosis[2,4,13]

Test result	Significance
Lymphocytes > 85%	Tuberculous pleural effusion, sarcoidosis, chronic rheumatoid pleurisy, yellow nail syndrome, chylothorax
Neutrophils > 10000 / µL	Para-pneumonic effusion, lupus pleuritis, acute pancreatitis
Neutrophils > 50000 / µL	Empyema
Red blood cells: pleural fluid to serum haematocrit value > 0.5	Haemothorax
Protein < 1 gm/dL	Peritoneal dialysis, central venous catheter migration, cerebrospinal fluid leakage into pleura
Protein > 4 gm/dL	Tuberculous pleural effusion
Eosinophils > 10%	Haemothorax, pulmonary infarction, benign asbestos pleurisy, coccidioidomycosis, drug-induced pleurisy, Churg-Strauss syndrome, polyarteritis nodosa, paragonimiasis and other parasites, Sarcoidosis, Hodgkin’s disease
Glucose: Pleural fluid to serum < 0.5	Complicated para-pneumonic effusion, chronic rheumatoid pleurisy, paragonimiasis, amoebic empyema, oesophageal rupture, tuberculous pleural effusion, lupus pleuritis, urinothorax
Glucose: pleural fluid to serum > 1	Peritoneal dialysis, central venous catheter migration
Lactate dehydrogenase > 1000 IU/L	Bacterial empyema, pancreatitis, pancreatic-pleural fistula, amoebic empyema, septic emboli, rheumatoid pleurisy
Pleural fluid pH < 7.3	Oesophageal rupture, chronic rheumatoid pleurisy, complicated para-pneumonic effusion, paragonimiasis, amoebic empyema, tuberculous pleural effusion, lupus pleuritis, urinothorax, pancreatic-pleural fistula
Elevated pleural fluid amylase	Oesophageal rupture, acute pancreatitis, pancreatic-pleural fistula
Creatinine: pleural fluid to serum > 1	Urinothorax
Cholesterol > 200 mg/dL	Pseudo-chylous effusion
Presence of chylomicrons	Chylothorax
Triglycerides > 110 mg/dL	Chylothorax, central venous catheter migration with lipid infusion
Beta 2 transferrin level elevated	Cerebro-spinal fluid leakage to pleura
Adenosine deaminase > 40 IU/dL with lymphocytosis.	Tuberculous pleural effusion

Table 4 The importance of pleural effusion in the intensive care unit setting and factors affecting the success rate of pleural effusion drainage:

Importance of pleural effusion in the ICU setting
1	Sometimes, the cause of ICU admission is the underlying cause of the pleural effusion
2	Difficult diagnosis of pleural effusion in the ICU: Clinical, Radiological, and Laboratory-related difficulties
3	Impaired turnover and cycling of pleural fluid in critically ill patients
4	The presence of pleural effusion affects the outcome and prognosis of ICU patients
5	Drainage of pleural effusion can modify the outcome and/or alter the diagnosis of patients
Factors affecting the success rate of pleural effusion drainage
1	Timing of drainage: Early versus late drainage
2	Patient-related factors: Proper selection of the patients
3	Etiology of the effusion: Traumatic versus post-operative versus empyema
4	Technical-related: Image-guided aspiration or not, Proper technique of drainage, Type of catheter used (pigtail catheter versus standard tube)

ICU: Intensive care unit.