Pleural Effusions



Pleural Effusions


Angela Lorts



INTRODUCTION

A pleural effusion is an accumulation of fluid between the parietal and visceral pleura. Normally, fluid is produced by the capillaries of the parietal pleura and absorbed by the capillaries of the visceral pleura; only a trivial amount of fluid is left within the pleural space. The Starling relationship governs the net flow of fluid at each capillary bed:


A larger difference between capillary and pleural hydrostatic pressure, or a smaller difference between capillary and pleural oncotic pressure, results in a larger amount of fluid left in the pleural space. Lymphatic drainage normally removes excess fluid from the pleural space. Accumulation of a pleural effusion may result from increased capillary hydrostatic pressure, decreased hydrostatic pressure in the pleural space, decreased capillary oncotic pressure, capillary leak, lymphatic obstruction, movement of fluid from the peritoneal space, or a combination of these factors.

Pleural effusions are classified according to their etiology as transudative or exudative. Pleural fluid analysis can often distinguish a transudate from an exudate and serves as the first step in the differential diagnosis.



  • Transudative effusions are usually secondary to increased capillary hydrostatic pressure or decreased capillary oncotic pressure. The most common etiology of a transudative effusion is congestive heart failure.


  • Exudative effusions are typically seen in diseases that injure the capillary membrane, result in increased capillary permeability, or impair lymphatic drainage. A broad differential diagnosis is implied by an exudative effusion and may require more extensive workup.



DIFFERENTIAL DIAGNOSIS LIST


Transudative Effusion



  • Cardiac



  • Congestive heart failure


  • Increased pulmonary arterial pressure


  • Superior vena caval obstruction


  • Constrictive pericarditis



  • Pulmonary



  • Acute atelectasis



  • Hepatic



  • Cirrhosis


  • Hypoalbuminemia



  • Renal



  • Peritoneal dialysis


  • Nephrotic syndrome



  • Iatrogenic



  • Extravasation from subclavian or jugular central venous lines into the pleural space



  • Endocrine



  • Hypothyroidism


Exudative Effusions



  • Infectious



  • Bacterial infection (Most common—Streptococcus pneumoniae, Staphylococcus aureus)


  • Viral infection (Most common—Adenovirus)


  • Mycoplasma infection


  • Fungal infection


  • Parasitic infection



  • Neoplastic



  • Hematologic neoplasm


  • Cervical teratoma


  • Pleural mesothelioma


  • Pheochromocytoma


  • Wilms tumor


  • Metastatic sarcoma—Ewing sarcoma, rhabdomyosarcoma, and clear cell sarcoma


  • Squamous cell carcinoma


  • Bronchogenic carcinoma



  • Gastrointestinal Disease



  • Esophageal rupture


  • Sub-diaphragmatic abscess


  • Pancreatic pseudocyst


  • Acute pancreatitis


  • Intrahepatic abscess



  • Pulmonary Disease



  • Pulmonary embolism


  • Acute respiratory distress syndrome


  • Chronic atelectasis


  • Hemothorax



  • Collagen Vascular Disease



  • Rheumatologic—rheumatoid arthritis, systemic lupus erythematosus, sarcoidosis, and Wegener granulomatosis


  • Sjögren syndrome



  • Lymphatic



  • Traumatic chylothorax


  • Obstruction of lymphatic drainage


  • Congenital lymphangiectasis


  • Noonan syndrome


  • Lymphedema



  • Iatrogenic



  • Radiation therapy


  • Surgery


  • Esophageal sclerotherapy


  • Extravasation from subclavian or jugular central venous lines


DIFFERENTIAL DIAGNOSIS DISCUSSION

If the etiology of the effusion is unclear, the distinction should be made between a transudate and an exudate by thoracentesis and pleural fluid analysis.



Transudative Effusions

Transudative effusions usually resolve with treatment of the underlying disease process.


Exudative Effusions: Infectious Causes

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Sep 14, 2016 | Posted by in PEDIATRICS | Comments Off on Pleural Effusions

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