What is the compositionof parietal and visveral pleura?
layers of collagen and elastin covered by a single cell layer of mesothelium
What does peluritic chest pain indicate?
involvement of the parietal pleura because
How much fluid is usually in the pleural space?
What are reasons why there would be excess fluid in the pleural space?
excess fluid in the lungs
cancer blocking drainage system
something disrupting the integrity of the membrane
What are the hypothesized roles for the visceral pleura?
provide mechanical support for the lung
function as a "reservoir" for lung water preventing the development of pulmonary edema
factors favoring the formation of pleural effusions
increased K or decreased R
accumulation of fluid from alterations of Starling forces across a normal membrane
protein-rich contents spilling into the pleural space resulting from alterations in the permeability of the membrane
1) pleural fluid total protein/serum toal protein > 0.5
2) pleural fluid LDH/serum LDH > 0.6
3) pleural fluid LDH > 2/3 of the upper normal value of serum LDH
an effusion is classified as an exudate if ANY ONE of these criteria are et
What are the top five causes of transudates?
congestive heart failure (increase Pcap)
liver cirrhosis (decreased πcap)
nephrotic syndrome (decreased πcap)
atelectasis (decreased Ppleural)
atelectasis (decreased Ppleura)
What are the three mechanistic causes of exudates?
altered membrane permeability
grossly altered membrane
decreased lymph clearance
What are some common causes of exudates through altered membrane permeability?
collagen vascular diseases
occupational or drug induced pleural diseases
What are some common causes of exudates through grossly altered membrane?
thoracic duct rupture
What are some common causes of exudates through decreased lymph clearance?
malignant obstruction of the lymphatics
primary lymphatic diseases (yellow nail syndrome)
common symptoms of pleural effusions
large effusion can cause:
pleuritic chest pain - indicates inflammation
dyspnea from displacement of respiratory muscles
signs of pleural effusions
dullness to percussion
decreased tactile fremitus
tracheal devation away from the effusion
decreased breath sounds
What is the treatment for pleural effusion?
require drainage when they are large and symptomatic or when they are infected
if not large, a small aliquot is removed and analyzed in order to help establish a diagnosis of a systemic disease (thoracentesis)
causes of low pH effusions
parapneuonic effusions (main cause)
pH of less than 7.15 is an indication for drainage
causes of low glucose effusions
complicated parapneumonic effusions
malignancy wiht extensive pleural involvement
causes of high amylase effusions
other intrabdominal processes
How does cytology help the diagnosis of pleural effusions?
helps identify malignancies
up to 90% sensitivity with 2 thoracenteses
How does cell counts help the diagnosis of pleural effusions?
high cell counts with mostly PMNs indicate infection
mostly lymphocytes indicates malignancy, TB, or fungal effusions
presence of >5% mesothelial cells speaks against diagnosis of TB
RBC count of >/= 50% of that in peripheral blood indicates hemothorax
less than 5% mesothelial cells
adenosine deaminase > 47 IU/L
(deaminase < 47 means no TB) high sensitivity
causes of pneumothorax
signs of tension pneumothorax
increased ypmani of same side
requires immediate decompression