Pleural Diseases Flashcards
pleural effusion - defined
*an abnormal collection of fluid in the pleural space that is clinically detectable
*pleural effusions suggest pulmonary, pleural, or extrapulmonary disease
*results from an imbalance between fluid formation and removal
pleural fluid formation & drainage
*pleural fluid flows in a horizontal direction, from costal to mediastinal regions
*pleural lymphatic flow mostly localized to diaphragm & mediastinal surfaces
*homeostatic balance between capillary filtration & lymphatic absorption (hydrostatic push and oncotic pull)
pleural effusion: physical exam findings
*diminished breath sounds
*dullness to percussion
*decreased tactile fremitus
pleural effusion: radiographic confirmatory studies
*ultrasound most common
*plain CXR (demonstrates costophrenic angle blunting, especially on lateral view)
*CT
note - PFTs would show decreased TLC and FVC (restrictive defect)
pleural effusion: targeted history
ALWAYS INVESTIGATE:
*duration of the effusion
*previous pneumonia or pleurisy
*CABG surgery, esp. with harvesting of the internal mammary arteries
*history of radiation treatment
*remote asbestos exposure
*history of travel, residence
thoracentesis for pleural effusion
*placement of a needle into the pleural space (without hitting the lung)
*can be used to treat pleural effusion by removing/reducing the lung
*can also be beneficial for diagnosis to examine the pleural fluid
classifications of pleural effusions
- transudative
- exudative
transudative pleural effusions
*clear fluid (hypocellular)
*results from alterations in systemic factors that influence movement of fluid in and out of the pleural space with a net accumulation of fluid
*due to INCREASED HYDROSTATIC PRESSURE and/or DECREASED ONCOTIC PRESSURE
*common causes: heart failure, liver disease, kidney disease
exudative pleural effusions
*cloudy fluid (cellular)
*due to infection, malignancy, connective tissue disease, lymphatics, or trauma
*often requires drainage due to increased risk of infection
*common causes: pneumonia, malignant pleural disease, pulmonary embolism, and GI disease
normal pleural fluid
*protein concentration about 15 g/L
*clear/light yellow
*< 500 nucleated cells/microliter (differential: 2% neutrophils, 0% basophils, 7-11% lymphocytes, 61-77% MACROPHAGES, 9-30% MESOTHELIAL CELLS)
*pH 7.45-7.60
*glucose equivalent to serum glucose level
Light’s Criteria for categorizing transudative vs. exudative pleural effusions
*any one of the following is consistent with an exudative pleural effusion; all 3 increases the surety:
1. pleural fluid (PF) LDH > two-thirds of the upper limit of normal serum LDH (~170)
2. PF LDH / serum LDH ratio > 0.6
3. PF protein / serum protein ration > 0.5
5 key pathophysiological mechanisms for pleural fluid accumulation
- increased transpleural pressure (ex. CHF) - transudate
- decreased oncotic pressure (ex. hypoalbuminemia, cirrhosis) - transudate
- increased capillary permeability (ex. pneumonia) - exudate
- impaired lymphatic drainage (ex. malignancy) - exudate
- transdiaphragmatic movement of fluid from the pleural space (ex. hepatic hydrothorax) - transudate
core studies for pleural effusions
*total protein
*LDH
*pH
*glucose
*gram stain with cultures
*cytology
main pleural fluid chemistry: LDH
*helpful in assessing the degree of pleural inflammation
*helps to differentiate transudates from exudates
*increasing level implies progressive pleural inflammation and a decreasing level implies decreasing pleural inflammation
main pleural fluid chemistry: glucose
- < 60 mg/dl implicates increased cell metabolism, as can be seen with active inflammation
*TB, parapneumonic effusion, malignancy, or connective tissue disorders associated with low glucose
quick DDx for transudative pleural effeusions
*changes in hydrostatic or oncotic pressure gradient
*most common causes:
-CHF with systemic venous hypertension
-atelectasis
-cirrhosis
-nephrotic syndrome
-hepatic hydrothorax
transudative pleural effusion due to hepatic hydrothorax
*liver cirrhosis and portal hypertension without cardiac or pulmonary pathology
*most commonly right sided
*ascites traversing from peritoneal space to pleural space via diaphragmatic fenestrations & pressure gradient (peritoneal space = high pressure; pleural space = low pressure)
transudative pleural effusion due to nephrotic syndrome
*excessive loss of plasma proteins in urine
-includes: hypoalbuminemia, hypercholesterolemia, & peripheral edema
*excretion of total proteins > 3.5 g/day
quick DDx for exudative pleural effusions
*due to pleural inflammation, increased capillary permeability, or impaired lymphatic drainage
*most common causes:
-INFECTION
-MALIGNANCY
-immunologic/inflammatory disorders
-lymphatic disorders
-asbestos related
exudative pleural effusion due to malignancy
*large, unilateral, bloody, exudative pleural effusion
*diagnostic yield of pleural fluid cytology = 66%
exudative pleural effusion due to tuberculosis
*pleural fluid adenosine deaminase (ADA) level > 40
*lymphocyte/neutrophil ration > 0.75 (> 60% lymphocytes)
exudative pleural effusion due to rheumatoid arthritis
*most common intrathoracic manifestation of rheumatoid arthritis
*typically pH < 7.20, glucose < 50 mg/dL, pleural serum/glucose ratio < 0.5, elevated LDH (>1000), rheumatoid titer > 1:320
*associated with rheumatoid nodules
exudative pleural effusion due to systemic lupus erythematosus (SLE)
*SLE can commonly cause pleural effusion
*check ANA levels and look for presence of lupus cells
exudative pleural effusion due to chylothorax
*appearance is turbid or milky, due to chyle in pleural space from thoracic duct obstruction
*pleural fluid TRIGLYCERIDE > 110 mg/dL (check chylomicrons)
*common causes: trauma (injury to thoracic duct) or malignancy (lymphoma)
