Source: http://emedicine.medscape.com/article/299959 Pleural Effusion Prof KR Sethuraman. MD Source: http://emedicine.medscape.com/article/299959

Learning Outcomes

It is the most common manifestation of pleural disease Definition A pleural effusion is an abnormal collection of fluid in the pleural space resulting from excess fluid production or decreased absorption. It is the most common manifestation of pleural disease

Anatomy of The Pleural Space bordered by the parietal and visceral pleurae The parietal pleura covers the inner surface of the thoracic cavity, including the mediastinum, diaphragm, and ribs. The visceral pleura envelops all lung surfaces, including the interlobar fissures. The right and left pleural spaces are separated by the mediastinum (heart & other midline structures).

The Pleural space in Respiration a relative vacuum in the space keeps the visceral and parietal pleurae in close proximity. pleural fluid is a lubricant between the pleural surfaces rubbing against each other during respiration. This small volume of fluid, 0.13 mL/kg of body weight, (10 ml for an average adult) is maintained through the balance between hydrostatic pressure and oncotic pressure & lymphatic drainage, any disturbance of these 3 may lead to pathology

Lung Recoil

The net result of effusion formation is mechanical separation of the visceral and parietal pleura, shift of the mediastinum to the opposite side and a restrictive ventilatory defect a flattening or inversion of the diaphragm

Aetiology Pleural effusion is an indicator of an underlying disease process that is pulmonary or non-pulmonary in origin may be acute or chronic most pleural effusions are caused by congestive heart failure, pneumonia, tuberculosis malignancy, or pulmonary embolism.

Pathophysiologic mechanisms -i Altered permeability of the pleural membranes e.g., inflammation, malignancy, pulmonary embolus Reduction in intra-vascular oncotic pressure e.g., hypoalbuminemia, cirrhosis Increased capillary permeability or vascular disruption e.g., trauma, malignancy, inflammation, infection, pulmonary infarction, drug hypersensitivity, uremia, pancreatitis

Pathophysiologic mechanisms -ii Increased capillary hydrostatic pressure in the systemic and/or pulmonary circulation e.g., congestive heart failure, superior vena cava syndrome Reduction of pressure in the pleural space, preventing full lung expansion e.g., extensive atelectasis, mesothelioma Increased peritoneal fluid, with migration across the diaphragm via the lymphatics or structural defect e.g., cirrhosis, peritoneal dialysis Decreased lymphatic drainage or complete blockage, including thoracic duct obstruction or rupture eg, malignancy, trauma

Classification Pleural effusions are generally classified as Transudates (watery fluid) or Exudates (protein-rich fluid), based on the mechanism of fluid formation and pleural fluid chemistry. Transudates result from an imbalance in oncotic and hydrostatic pressures, whereas Exudates are the result of inflammation of the pleura or decreased lymphatic drainage.

Why worry Transudate or Exudate? differentiating between transudates and exudates is a useful first step in the study of any pleural effusion of unknown cause. As a general rule, once an effusion has been classified as a transudate, further diagnostic procedures or studies of the pleural tissues are unnecessary

Transudate Exudate Tuberculosis Congestive heart failure TB pericarditis Para-pneumonic cause Malignancy lung or breast cancer, lymphoma Pulmonary embolism Collagen-vascular conditions (SLE) Radiation pleuritis Congestive heart failure Constrictive pericarditis Hypoalbuminemia Cirrhosis Nephrotic syndrome Peritoneal dialysis Myxedema

Epidemiology 320 cases per 100,000 people in industrialized countries Estimate: 3200 x 27 = 86400 in Malaysia About 2/3 of malignant pleural effusions occur in women associated with breast and gynecologic malignancies.

Morbidity and Mortality directly related to the aetiology, stage of disease Early or late & biochemical findings in the pleural fluid. E.g., lower pleural fluid pH is associated with a worse prognosis a malignant pleural effusion is associated with a very poor prognosis median survival of 4 months and mean survival of less than 1 year in men: lung cancer in women: breast cancer

The clinical manifestations The most commonly associated symptoms are progressive dyspnea, dry cough, and pleuritic chest pain orthopnea with large effusion (the inability to breathe easily unless the person is sitting up straight). Dyspnea is related more to distortion of the diaphragm and chest wall during respiration than to hypoxemia. Cough with purulent or bloody sputum suggests pneumonia or endobronchial tumour as the aetiology

Pleuritic Pain chest pain, indicates pleural irritation, suggests an exudative etiology, such as pleural infection, mesothelioma, or pulmonary infarction Pain may be mild or severe. It is typically described as sharp or stabbing and is exacerbated with deep inspiration. owing to diaphragmatic involvement, pain can be referred to the ipsilateral shoulder (phrenic nerve root C4) or upper abdomen

Physical Examination asymmetrical chest expansion Diminished expansion on the side of the effusion decreased tactile fremitus Dullness to percussion Mediastinal shift away from the effusion Large effusion >1litre No physical findings for effusions smaller than 300 mL With effusions larger than 300 mL, more reliable physical findings include the following:

Percussion: the key to diagnosing Effusion Pleximeter is the left middle finger used in percussion to absorb the energy generated by the strike from the Plexor finger (right middle or index finger)

Inventor of Percussion technique Leopold Auenbrugger Austrian physician who invented percussion as a diagnostic technique. On the strength of this discovery, he is considered one of the founders of modern medicine. Leopold Auenbrugger (1722–1809) was born in Graz, the son of an innkeeper. Legend has it that his discovery of percussion was based upon observing his father tap wine casks in order to ascertain the amount of wine present in the cask.

Physical signs - ii Diminished or inaudible breath sounds Egophony at the upper border of the pleural effusion (vocal resonance of "aah“ sounds like “ee”) Pleural friction rub in inflammatory lesions with mild effusion Other signs: CCF, Cirrhosis of liver, nephrotic syndrome, etc

Chest Radiography Effusions >175 mL are seen as blunting of the costophrenic angle on upright postero-anterior chest radiographs.

Erect vs Supine On supine chest radiographs, moderate to large pleural effusions may appear as a homogenous increase in density spread over the lower lung fields. Supine AP view Erect PA view

Minimal Rt Basal Effusion Chest CT scanning in all patients with an undiagnosed pleural effusion to detect thickened pleura or signs of invasion of underlying or adjacent structures. diagnostic imperatives in this situation are pulmonary embolism and tuberculous pleuritis Eff Minimal Rt Basal Effusion Lt Effusion + Hilar Lymphadenpathy ( )

Ultrasonography of Effusion Very sensitive Non-invasive Useful to confirm the diagnosis Guides aspiration Placement of needle Depth of needle insertion Right Lateral Decubitus (supine) view at Mid-clavicular line of the liver, diaphragm and right hemi-thorax

Diagnostic Thoracentesis performed for new & unexplained pleural effusions when sufficient fluid is present to allow a safe procedure. gross characteristics of the fluid gives clues: purulent fluid (pus) indicates an empyema bloody fluid may result from trauma or malignancy, 

Normal Pleural Fluid A pH of 7.60-7.64 Clear ultrafiltrate of plasma that originates from the parietal pleura A pH of 7.60-7.64 Protein content of less than 2% (1-2 g/dL) Fewer than 1000 white blood cells (WBCs) per cubic millimeter Glucose content similar to that of plasma Lactate dehydrogenase (LDH) less than 50% of plasma

Transudate Exudate Tuberculosis Congestive heart failure TB pericarditis Para-pneumonic cause Malignancy lung or breast cancer, lymphoma Pulmonary embolism Collagen-vascular conditions (SLE) Radiation pleuritis Congestive heart failure Constrictive pericarditis Hypoalbuminemia Cirrhosis Nephrotic syndrome Peritoneal dialysis Myxedema

Differentiating Transudates From Exudates (Light’s criteria) The fluid is considered an exudate if any of the following applies: Ratio of pleural fluid to serum protein > 0.5 Ratio of pleural fluid to serum LDH > 0.6 Pleural fluid LDH > two-thirds of the upper limits of normal serum value { Light’s criteria }

Pleural Fluid pH & Glucose A pleural fluid pH of less than 7.30 with a normal arterial blood pH correlates well with low pleural fluid glucose seen in exudates In para-pneumonic effusion, A very low pleural glucose concentration (ie, < 30 mg/dL) & pleural fluid pH of <7.2 indicates the need for urgent drainage of the effusion & >7.3 (no drainage)

Pleural Fluid Cell Count - 1 If exudate, then do cytology of pleural fluid Pleural fluid lymphocytosis, with lymphocyte values greater than 85% of the total nucleated cells, suggests TB, lymphoma, sarcoidosis, chronic rheumatoid effusion, chylothorax. Pleural lymphocyte values of 50-70% of the nucleated cells suggest malignancy.

TB pleural effusion Suspected in patients with a history of exposure or a positive PPD finding and in patients with lymphocytic exudative effusions, Effusion results from a hypersensitivity reaction to the Mycobacterium. So, acid-fast bacillus stains of pleural fluid are rarely diagnostic pleural fluid cultures grow M tuberculosis in <65% of cases; pleural biopsy is + in 90% cases

Therapeutic Thoracentesis to remove larger amounts of pleural fluid to alleviate dyspnea in parapneumonic effusions, to prevent ongoing inflammation and fibrosis avoid producing a pneumothorax during the removal of large quantities of fluid avoid re-expansion pulmonary oedema The recommended limit is 1 - 1.5 Liters in a single thoracentesis procedure

This is for self study later…

Thank you !

Pleural Fluid Cell Count - 2 Pleural fluid eosinophilia (PFE), with eosinophils >10% of nucleated cells, is seen in haemothorax, pneumothorax, pulmonary infarction, parasitic diseases, etc. Mesothelial cells are found in variable numbers in most effusions, but their presence at greater than 5% of nucleated cells makes a diagnosis of TB less likely.