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11-2-b-Disorders of the Pleura Lab
- 56-y o woman with a four year history of severe rheumatoid arthritis is evaluated because of chest pain and a persistent left-sded pleural effusion
- High specific gravity: .
- 60%PMNs, high LDH, 20% monocytes, 15% lymphocytes, 5% eosinophils
- Low glucose (47 mg/dL): .
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Normally – primary source of the fluid in pleural space
Parietal pleura
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Almost all fluid is removed via
Stomata on the parietal pleura of the lower chest wall, low mediastinum and diaphragms that communicate with lymphatics
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Causes of increased pleural fluid formation
- Increased interstitial fluid in the lung: increased pulmonary venous pressure (CHF, mitral stenosis, increased permeability of pulmonary vessels[bacterial pneumonia, diffuse alveolar damage, PE, Rheumatoid lung disease])
- Elevation of the systemic venous pressure: right and left ventricular heart failure and superior vena cava syndrome
- Decrease in oncotic pressure in the microvascular circulation: cirrhotic liver diseases, nephritic syndrome, severe protein malnutrition – low serum albumin level in all
- Decreased pleural pressure (increased negative pleural pressure): bronchial obstruction leading to atelectasis
- Movement of fluid from the peritoneal cavity: any condition causing ascites – passage through diaphragmatic lymphatics or diaphragmatic defects
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Causes of decreased pleural fluid absorption
- Obstruction of the lymphatics that drain the parietal pleura: a blockage at any point in the lymphatic system [ tumor or fibrosis]
- Elevation of pressure in the central veins: superior vena cava syndrome and right-sided heart failure
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Three most common causes of a pleural effusion
- CHF – transudative
- Bacterial pneumonia – exudative
- Malignant disease – exudative
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Other causes of a pleural effusion
- PE
- Viral infections
- Cirrhosis, ascites
- GI disease
- Collagen Vascular Disease – Rheumatoid, SLE, Wegener’s granulomatosis
- TB
- Asbestos
- Drugs
- Post-MI
- Meig’s syndrome – ovarian tumor (fibroma) plus right-sided pleural effution
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Pleural effusion due to rheumatoid pleuritis
- Fibrinous exudate, some neutrophils and neutrophil debris
- Rheumatoid nodules: nodular aggregates of palisaded histiocytes and fibroblasts that surround central areas of fibrinoid necrosis – CHARACTERISTIC
- Most common thoracic manifestation of rheumatoid disease
- Typically unilateral: .
- Exudative with a high protein level and it usually shows low glucose levels: <50mg/dL and very high LDH
- Male predominance, within 5 years of Rheumatoid arthritis Dx; subcutaneous nodules present: .
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Parapneumonic effusion – loculated effusion
Empyema: pus in the pleural space; purulent, complicated parapeumonic effusion in a patient with bacterial pneumonia
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Malignant pleural effusions
- Primary but more commonly metastatic
- Dx: microscopid identification of malignant cells in pleural fluid samples or in pleural tissue biopsies
- Lung carcinoma (30%), breast carcinoma (25%) and lymphomas 20%: .
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First step in developing a DDx of a pleural effusion
- Is to establish whether the effusion is a transudate or an exudate by Dx thoracentesis
- Then cell counts, cytology, culture for microorganisms, other tests – glucose, pH, amylase, serologic tests
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Cell counts on fluid samples
- Lymphocyte predominance: TB
- PMN predominance: parapneumonic effusions
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Pneumothorax
- Primary spontaneous pneumothorax: most often in tall, thin, young men when an apical subpleural bleb ruptures, smokers; sudden chest pain and dyspnea; most resolve spontaneously
- Secondary spontaneous pneumothorax: removal of air from the pleural space with a chest tube is required and thorascopic surgery to repair the air leak[can be from: COPD (emphysema), PCJ infection in patients with AIDS, eosinophilic granuloma of the lung, necrotizing pneumonias, TB and lymphangiomyomatosis
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Traumatic pneumothorax
From penetrating and nonpenetrating chest trauma
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Iatrogenic pneumothorax
- High incidence
- Major causes: transthoracic needle aspiration, subclavian needle stick, thoracentesis, pleural biopsy, positive pressure ventilation
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Pneumothorax
Whe the defect that connects the air-filled lung to the pleural space acts as a flap valve that permits air to enter the pleura during inspiration, but fails o permit its escape during expiration
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Hemothorax
- Presence of significant blood in the pleural space
- Hematocrit at least 50% of the peripheral blood
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