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
when would you do a cytologic examination?
if malignancy is at all suspected
ADA levels more than 40 and predominant lymphocytes
diagnostic of tuberculosis
top 4 causes of pleural effusion
- CHF
- parapneumonic
- malignancy
- PE
what is empyema?
pus in pleura
characteristics associated with a bad parapneumonic effusion prognosis
pos gram stain or culture
pH less than 7.2
glucose less than 60
presence of pus
complicated vs uncomplicated effusion treatment
uncomplicated: just antibiotics
complicated: drainage and antibiotics, possibly surgery
milky or opaque effusion?
high lipid content or empyema
what is ALWAYS a good first step in a suspected PE?
CXR and then diagnostic thoracentesis
what is loculation?
occurs in complicated effusions
fluid gets encapsulated by fibrous tissue
