B4.026 Pleural Effusion Flashcards
how does liquid get into the pleural space?
intrapleural pressure is lower than interstitial pressure in visceral or parietal pleura, so pressure gradient moves liquid into the space
where does normal pleural liquid come from
mainly systemic vessels of pleural membranes, not pulmonary vessels
volume of pleural liquid
small
0.1-0.2 ml/kg
how is pleural fluid reabsorbed?
initially partially reabsorbed by the microvessels
remaining fluid exits via lymphatics in parietal pleura
what is the effect of accumulation of fluid in the pleural space?
effects the elastic equilibrium volumes of the lung and chest wall
results in restrictive ventilatory effect, chest wall expansion, and reduced efficiency of the inspiratory muscles
what happens when lung volume is decreased?
associated with hypoxia
increased right to left shunt
basic mechanism that can result in pleural effusions
increased transpleural pressure gradient (CHF)
increased capillary permeability (parapneumonic)
impaired lymphatic drainage (malignancy)
transdiaphragmatic movement of fluid from the peritoneal cavity (ascites)
pleural effusions of extravascular origin (chylothorax)
Light’s Criteria for an exudate
any of the following met:
PF/serum protein > 0.5
PF/serum LDH > 0.6
PF LDH > 2/3 upper normal serum limit
common causes of transudate effusions
CHF, cirrhosis, nephrosis
routine tests on pleural fluid
protein LDH description of fluid cell count and differential glucose pH cytology smears and cultures ADA
predominantly neutrophils in a pleural effusion?
pleural process is acute
possibly parapneumonic
predominantly small lymphocytes?
tuberculosis, malignancy, or post surgery CABG pleural effusion
eosinophilic pleural effusion?
idiopathic or malignancy
low pleural fluid glucose?
1 of 4 options: complicated parapneumonic malignant tuberculosis rheumatoid
low pH?
parapneumonic
metabolic activity from cell and bacterial accumulation can lower pH
lower the pH = the more serious and higher possibility of surgery
