11-2-b-Disorders of the Pleura Lab.txt

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11-2-b-Disorders of the Pleura Lab.txt
2010-11-02 21:06:27

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  1. 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): .
  2. Normally – primary source of the fluid in pleural space
    Parietal pleura
  3. Almost all fluid is removed via
    Stomata on the parietal pleura of the lower chest wall, low mediastinum and diaphragms that communicate with lymphatics
  4. 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
  5. 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
  6. Three most common causes of a pleural effusion
    • CHF – transudative
    • Bacterial pneumonia – exudative
    • Malignant disease – exudative
  7. 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
  8. 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: .
  9. Parapneumonic effusion – loculated effusion
    Empyema: pus in the pleural space; purulent, complicated parapeumonic effusion in a patient with bacterial pneumonia
  10. 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%: .
  11. 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
  12. Cell counts on fluid samples
    • Lymphocyte predominance: TB
    • PMN predominance: parapneumonic effusions
  13. 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
  14. Traumatic pneumothorax
    From penetrating and nonpenetrating chest trauma
  15. Iatrogenic pneumothorax
    • High incidence
    • Major causes: transthoracic needle aspiration, subclavian needle stick, thoracentesis, pleural biopsy, positive pressure ventilation
  16. 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
  17. Hemothorax
    • Presence of significant blood in the pleural space
    • Hematocrit at least 50% of the peripheral blood