Dr. A.Torossian, M.D., Ph. D. Department of Respiratory Diseases

Transcription

1 Pleural effusions Dr. A.Torossian, M.D., Ph. D. Department of Respiratory Diseases A pleural effusion is an abnormal collection of fluid in the pleural space resulting from excess fluid production or decreased absorption. 1

2 o The pleural space is bordered by the parietal and visceral pleurae. o A relative vacuum in the space keeps the visceral and parietal pleurae in close proximity. 2

3 o The normal pleural space contains approximately 1 ml of fluid, representing the balance between (1) hydrostatic and oncotic forces in the visceral and parietal pleural vessels and (2) extensive lymphatic drainage. Pleural effusions result from disruption of this balance Mechanisms playing a role in the formation of pleural effusion: o Altered permeability of the pleural membranes (eg, inflammation, malignancy, pulmonary embolus) o Reduction in intravascular oncotic pressure (eg, hypoalbuminaemia, cirrhosis) o Increased capillary permeability or vascular disruption (eg, trauma, malignancy, inflammation, infection, pulmonary infarction, drug hypersensitivity, uremia, pancreatitis) o Increased capillary hydrostatic pressure in the systemic and/or pulmonary circulation (eg, congestive heart failure, superior vena cava syndrome) 3

4 o Decreased lymphatic drainage or complete blockage, including thoracic duct obstruction or rupture (eg, malignancy, trauma) o Reduction of pressure in the pleural space, preventing full lung expansion (eg, extensive atelectasis, mesothelioma) o Increased peritoneal fluid, with migration across the diaphragm via the lymphatics or structural defect (eg, cirrhosis, peritoneal dialysis) o Movement of fluid from pulmonary edema across the visceral pleura Pleural effusion is an indicator of an underlying disease that may be pulmonary or nonpulmonary in origin and may be acute or chronic! 4

5 o Pleural effusions are generally classified as transudates or exudates, based on the mechanism of fluid formation and pleural fluid chemistry. o Transudates result from an imbalance in oncotic and hydrostatic pressures, whereas exudates are the result of inflammation of the pleura or decreased lymphatic drainage. o In some cases, the pleural fluid may have a combination of transudative and exudative characteristics. Transudates o Transudates are usually ultrafiltrates of plasma in the pleura due to imbalance in hydrostatic and oncotic forces in the chest. However, they can also be caused by the movement of fluid from peritoneal spaces or by iatrogenic infusion into the pleural space from misplaced or migrated central venous catheters or nasogastric feeding tubes. 5

6 Transudates o Congestive heart failure (most common) o Cirrhosis o Nephrotic syndrome o Peritoneal dialysis o Hypoproteinemia o Glomerulonephritis o Superior vena cava obstruction o others Exudates o Exudates arise from pleural or lung inflammation, impaired lymphatic drainage of the pleural space, transdiaphragmatic movement of inflammatory fluid from the peritoneal space, altered permeability of pleural membranes, and increased capillary wall permeability or vascular disruption. o Permeability of pleural capillaries to proteins is high, resulting in an elevated protein content. 6

7 Exudates o Pneumonia o Malignancy (most commonly, lung or breast cancer, lymphoma, leukemia; less commonly, ovarian carcinoma, stomach cancer, sarcomas, melanoma and others) o Tuberculosis (TB) o Pulmonary embolism o Collagen-vascular conditions (rheumatoid arthritis, systemic lupus erythematosus. others) o Pancreatitis o Trauma o Postcardiac injury syndrome o Meigs syndrome o Drug-induced pleural disease o Asbestos pleural effusion o Yellow nail syndrome o Uremia o Trapped lung o Chylothorax o Pseudochylothorax o Acute respiratory distress syndrome o others 7

8 o Congestive heart failure, bacterial pneumonia, malignancy, and pulmonary embolus are responsible for most of the cases. o Approximately 20% of the effusions remain undiagnosed. Pleural effusion is usually secondary to other underlying disease! 8

9 Diagnosis History 1.Clinical manifestations of the underlying disease 2.Symptoms of pleural effusion: o progressive dyspnea o cough o pleuritic chest pain 3.Small effusions may be unnoticed Other important information-concomitant diseases, operations, medications, occupation, etc. Physical Examination o Physical findings in pleural effusion are variable and depend on the volume of the effusion. o Generally, there are no physical findings for effusions smaller than 300 ml. 9

10 o Dullness to percussion, decreased tactile fremitus, and asymmetrical chest expansion, with diminished or delayed expansion on the side of the effusion, are the most reliable physical findings of pleural effusion. o Diminished or inaudible breath sounds o Egophony (bronchophony) at the most superior aspect of the pleural effusion o Pleural friction rub othe patient should be examined in details, physical findings from another site may suggest the underlying cause of the pleural effusion. 10

11 Chest Radiography o Effusions of more than 175 ml are usually apparent as blunting of the costophrenic angle on upright posteroanterior chest radiographs. o On supine chest radiographs, which are commonly used in the intensive care setting, moderate to large pleural effusions may appear as a homogenous increase in density spread over the lower lung fields. 11

12 Lateral decubitus films more reliably detect smaller pleural effusions. Layering of an effusion on lateral decubitus films defines a freely flowing effusion and, if the layering fluid is 1 cm thick, indicates an effusion of greater than 200 ml that is amenable to thoracentesis. Failure of an effusion to layer on lateral decubitus films indicates the presence of loculated pleural fluid or some other etiology causing the increased pleural density. Small pleural effusions may be detected with CT and ultrasonography 12

13 omediastinal shift away from the effusion - effusions greater than 1000 ml; o DD with athelectasisdisplacement of the trachea and mediastinum toward the side of the effusion 13

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15 CT Scanning and Ultrasonography o Loculated pleural effusions o Underlying lung disease o Mediastinum CT Scanning and Ultrasonography o Chest CT scanning with contrast should be performed in all patients with an undiagnosed pleural effusion, if it has not previously been performed, to detect thickened pleura or signs of invasion of underlying or adjacent structures. o CT angiography should be ordered if pulmonary embolism is strongly suggested. 15

16 Diagnostic Thoracentesis o Perform diagnostic thoracentesis if the etiology of the effusion is unclear or if the presumed cause of the effusion does not respond to therapy as expected. o Pleural effusions do not require thoracentesis if they are too small to safely aspirate or, in clinically stable patients, if their presence can be explained by underlying congestive heart failure (especially bilateral effusions) or by recent thoracic or abdominal surgery. o o o o Laboratory testing helps to distinguish pleural fluid transudates from exudates; however, certain types of exudative pleural effusions might be suspected simply by observing the gross characteristics of the fluid obtained during thoracentesis. Frankly purulent fluid indicates an empyema A putrid odor suggests an anaerobic empyema A milky, opalescent fluid suggests a chylothorax, resulting most often from lymphatic obstruction by malignancy or thoracic duct injury by trauma or surgical procedure Grossly bloody fluid may result from trauma, malignancy, postpericardiotomy syndrome, PE or asbestos-related effusion and indicates the need for a spun hematocrittest of the sample; a pleural fluid hematocrit level of more than 50% of the peripheral hematocrit level defines a hemothorax, which often requires tube thoracostomy 16

17 Characteristics of the normal pleural fluid o ph of o Protein content of less than 2% (1-2 g/dl) o Fewer than 1000 white blood cells (WBCs) per cubic millimeter o Glucose content similar to that of plasma o Lactate dehydrogenase (LDH) less than 50% of plasma Distinguishing transudates from exudates Light s criteria: The fluid is considered an exudate if any of the following applies: o Ratio of pleural fluid to serum protein greater than 0.5 o Ratio of pleural fluid to serum LDH greater than 0.6 o Pleural fluid LDH greater than two thirds of the upper limits of normal serum value 17

18 Pleural Fluid microbiology and Cytology o Culture of infected pleural fluid yields positive results in approximately 60% of cases; this occurs even less often for anaerobic organisms. o Because most tuberculous pleural effusions probably result from a hypersensitivity reaction to the Mycobacterium rather than from microbial invasion of the pleura, acid-fast bacillus stains of pleural fluid are rarely diagnostic (< 10% of cases), and pleural fluid cultures grow M tuberculosis in less than 65% of cases. Laboratory testing Pleural Fluid LDH, Glucose, and ph Pleural fluid LDH o Pleural fluid LDH levels greater than 1000 IU/L suggest empyema, malignant effusion, rheumatoid effusion, or pleural paragonimiasis. Pleural fluid LDH levels are also increased in effusions from Pneumocystis jiroveci (formerly, P carinii) pneumonia; Pleural fluid glucose and ph o A low pleural glucose concentration suggests malignant effusion, tuberculous pleuritis, esophageal rupture, lupus pleuritism, rheumatoid pleurisy or empyema. o A low pleural fluid ph level is more predictive of complicated effusions (that require drainage) than is a low pleural fluid glucose level. In such cases, a pleural fluid ph of less than indicates the need for urgent drainage of the effusion, while a pleural fluid ph of more than 7.3 suggests that the effusion may be managed with systemic antibiotics alone. 18

19 Pleural Fluid Cell Count Differential o o Pleural fluid lymphocytosis, with lymphocyte values greater than 85% of the total nucleated cells, suggests TB, lymphoma, sarcoidosis, chronic rheumatoid pleurisy, yellow nail syndrome, or chylothorax. Pleural lymphocyte values of 50-70% of the nucleated cells suggest malignancy. Pleural fluid eosinophilia (PFE), with eosinophil values greater than 10% of nucleated cells, is seen in approximately 10% of pleural effusions and is not correlated with peripheral blood eosinophilia. PFE is most often caused by air or blood in the pleural space. Blood in the pleural space causing PFE may be the result of pulmonary embolism with infarction or benign asbestos pleural effusion, other nonmalignant diseases, including parasitic disease (especially paragonimiasis), fungal infection (coccidioidomycosis, cryptococcosis, histoplasmosis), and a variety of medications. Pleural Fluid Cell Count Differential o The presence of PFE does not exclude a malignant effusion, especially in patient populations with a high prevalence of malignancy. o Mesothelial cells are found in variable numbers in most effusions, but their presence at greater than 5% of total nucleated cells makes a diagnosis of TB less likely. Markedly increased numbers of mesothelial cells, especially in bloody or eosinophilic effusions, suggests pulmonary embolism as the cause of effusion. 19

20 Additional Laboratory Tests o o o o o Additional specialized tests are warranted when specific etiologies are suspected. Measure pleural fluid amylase levels if a pancreatic origin or ruptured esophagus is suspected or if a unilateral, left-sided pleural effusion remains undiagnosed after initial testing. Measure triglyceride and cholesterol levels in milky pleural fluids when chylothorax or pseudochylothoraxis suspected. ADA activity of greater than 43 U/mL in pleural fluid supports the diagnosis of tuberculous pleuritis. However, the test has a sensitivity of only 78%; therefore, pleural ADA values of less than U/mL do not exclude the diagnosis of TB pleuritis. Consider immunologic studies, including pleural fluid antinuclear antibody and rheumatoid factor, when collagenvascular diseases are suspected. PCR for DNA of M. Tuberculosis Contraindications o Relative contraindications to diagnostic thoracentesis include a small volume of fluid (< 1 cm thickness on a lateral decubitus film), bleeding diathesis or systemic anticoagulation, mechanical ventilation, and cutaneous disease over the proposed puncture site. 20

21 Complications o Complications of diagnostic thoracentesis include pain at the puncture site, cutaneous or internal bleeding, pneumothorax, empyema, and spleen/liver puncture. o Pneumothorax complicates approximately 12-30% of thoracenteses but requires treatment with a chest tube in less than 5% of cases. Invasive procedures o FBS o Pleural biopsy should be considered, especially if TB or malignancy is suggested. Medical thoracoscopy -a diagnostic tool to directly visualize and take a biopsy specimen from the parietal pleura in cases of undiagnosed exudative effusions. As an alternative, closed-needle pleural biopsy is a blind technique that can be performed at the patient's bedside. o others 21

22 oevery other test that can help the diagnosis of the underlying disease should be considered! Treatment o Treatment of the underlying disease o Treatment of the effusion - therapeutic thoracentesis, tube thoracostomy, rehabilitation, pleurodesis, placement of a Pleurex or Aspira Drainage Catheter (a 15Fr chest tube with a one-way valve). 22