Snapshot A 59-year-old man returns to the hospital with chest pain and difficulty breathing a couple of weeks after being discharged following a myocardial infarctation requiring immediate cardiac catheterization. He has been coughing up frothy sputum for the past three days. Introduction Pathologic accumulation of fluid in the pleural space often parapneumonic (in association with pneumonia) if infected, known as an empyema Effusions classified by pathogenesis and by using Light's criteria Light's Criteria: if any one of these is true, then the pleural fluid is likely exudative Pleural protein/serum ratio >0.5 Pleural LDH/serum ratio >0.6 Pleural LDH >2/3 the lab's upper limit of normal Transudative occur secondary to increased pulmonary capillary wedge pressure (PCWP) or decreased oncotic pressure Exudative occur secondary to increased pleural vascular permeability Transudative Exudative Intact capillaries lead to protein poor pleural fluid Inflammation leads to leaky capillaries, resulting in a protein rich pleural fluid Common causes include:CHFnephrotic syndromecirrhosisprotein losing enteropathySLE or RA Common causes include:malignancyTBbacterial infectionempyemaviral infectionsPE with infarctRA, SLEpancreatitispericarditispost-MIpneumoniapulmonary embolismtrauma specific gravity < 1.016 specific gravity > 1.016 Protein < 3 g/dl Protein > 3 g/dl pleural/serum protein < 0.5 pleural/serum protein > 0.5 pleural/serum LDH < 0.6 pleural/serum LDH > 0.6 Presentation Symptoms often asymptomatic may present with dyspnea pleuritic chest pain cough Presentation dullness to percussion decreased breath sounds over the effusion decreased tactile fremitus versus consolidation, which produces increased tactile fremitus Evaluation CXR shows blunting of the costophrenic angles decubitus CXR will identify free-flowing versus loculated fluid collections CT sometimes used to confirm diagnosis, if hesitant to proceed with thoracentesis Thoracentesis diagnostic gold standard indicated for new effusions >1cm in decubitus view send pleural fluid for CBC, protein, LDH, pH, glucose, Gram stain send for cytology if neoplasm is suspected use criteria in above table to classify the effusion Differential Etiologies listed above must all be considered in differential diagnosis prior to thoracentesis Treatment Non-operative treat underlying condition always indicated as first-line therapy Operative thoracentesis indicated for drainage of fluid collections pleurodesis indicated in malignant effusions that do not respond to chemo/radiation chest tube indicated, in addition to antibiotics, if evidence of a complicated pleural effusion or empyema large, loculated, pH < 7.2, or a positive Gram stain may also have glucose <50 or LDH > 1000 vs uncomplicated (small or moderate, pH >7.2), which is treated with only antibiotics indicated in the event of hemothorax Prognosis, Prevention, and Complications Prognosis ranges widely and depends highly on nature of underlying condition parapneumonic cases often resolve with the pneumonia Prevention early diagnosis and adequate treatment of some underlying conditions can prevent the development of a pleural effusion some etiologies are unpreventable pleurodesis is sometimes successful at preventing recurrence of effusion Complications can become infected and loculated, resulting in empyema requiring chest tube can recur and lead to chronic fibrosis and subsequent terminal lung disease