PATHOPHYS: Pleural Effusion Flashcards
What is the visceral pleura?
covering of lung surface (bumpy mesothelial cells with tight juncitons)
What is the parietal pleura?
covering of chest wall (tight mesothelial cells with loos juncitons)
What is the normal volume of the pleural fluid?
1-20 mL
What is the function of pleural fluid?
lubrication of the pleural space
What is a pleural effusion?
accumulation of fluid between the parietal and visceral pleura depending on hydrostatic and colloid osmotic pressures
What circulation supplies the parietal pleura?
systemic circulation (intercostal artery) HIGH PRESSURE
What circulation supplies the visceral pleura?
pulmonary circulation
LOW PRESSURE
What drives movement of fluid across the pleura? In what direction?
Hydrostatic pressure difference promotes the movement of fluid from the parietal pleura and into the pleural space through the leaky mesothelial junctions
True or false: the parietal pleura absorbs fluid while the visceral pleura forms it.
FALSE: parietal pleura forms 100 mL/hr while visceral pleura absorbs 300 mL/hr
How do proteins and cells get removed from the pleural space?
lymphatic drainage via the PARIETAL PLEURA (stomata–> lacunae–> ducts–> lymphatics–> mediastinal lymph nodes)
What two types of pleural effusions are there?
- exudates (protein rich)
- transudates (protein poor)
Name the 4 types of situations when pleural effusions occur?
- Increased hydrostatic pressure
- Decreased pleural pressure
- Decreased oncotic pressure
- Increased oncotic pressure (EXUDATE!!)
What is an example of a condition that will cause pleural effusion due to increased hydrostatic pressure?
Congestive heart failure (increased left sided pressure will cause the visceral pleura to FORM fluid)
What is an example of a condition that will cause pleural effusion due to decreased hydrostatic (pleural) pressure?
Atelectasis (lung collapse)–that low pressure will lead to increased fluid formation from both sides (especially parietal pleura)
What is an example of a condition that will cause pleural effusion due to increased oncotic pressure?
inflammation
infection
cancer
(these conditions decrease the oncotic pressure gradient so that there is movement of protein-rich exudate with increased COP into the pleural space from both pleuras)
What is an example of a condition that will cause pleural effusion due to decreased oncotic pressure?
Low albumin
(from malnutrition, renal loss, or decreased production that allows fluid to be released from both the visceral and parietal pleura)
List 2 characteristics of transudative effusion caused by CHF?
1) cardiomegaly
2) Bilateral effusions
What are the 3 major signs of pleural effusion on physical exam?
1) diminished or absent tactile fremitus
2) Diminished or absent breath and voice sounds
3) Dullness to percussion
What are the top 5 causes of pleural effusions?
1) CHF
2) Pneumonia
3) Malignant disease
4) Pulmonary embolism
5) Cirrhosis with ascites
What are the top 2 causes of malignant effusions?
Lung cancer
breast cancer
(closest to lung and have proximity to the pleural space)
What are the two major properties that control arrangement of fluid in the pleural space?
1) gravity
2) elastic recoil of the lung
What is the major cause of sepsis without other radiographic abnormalities?
Tb
What are the major causes of bilateral effusions?
CHF (with cardiomegaly) Malignancy Cirrhosis with ascites RA Lupus
What is the indication for a thoracentesis?
> 10 mm on lateral decubitis X-ray
What are the criteria for a pleural fluid to be exudate?
Pleural/serum protein ratio of >0.5
Pleural/serum LDH ratio > 0.6
Pleural fluid LDH of > two thirds upper limit of normal serum level
What are the 3 major things that cause a transudate?
CHF
Nephrotic syndrome
Cirrhosis with ascites
Having extremely high levels of WBCs in pleural fluid (>50,000) indicates what cause?
ONLY parapneumonic effusions
What will be seen in pleural fluid of empyema?
pus
What tests should be run on pleural fluid of expected Tb?
AFB (but NOT sensitive)
ADA
Pleural fluid caused by chylothorax will have what feature?
Tg >110
Pleural fluid caused by esophageal rupture will have what features?
high amylase
pH of 6 or below
How can you tell a traumatic thoracentesis from a hemothorax?
non-uniform color distribution during aspiration and clotting of fluid within minutes (shows it is fresh blood from piercing vessel on way to pleural cavity)
What conditions will cause low pleural fluid glucose?
- Rheumatoid pleurisy
- Empyema
- Malignant effusions
What are the two most common causes of pleural fluid acidosis?
Esophageal rupture
empyema
rheumatoid pleurisy
What is the most common cause of pleural fluid amylase/serum amylase to be >/= 1?
Acute pancreatitis
What are the 3 most common causes of exudate effusion?
Cancer
Infection
CTD
What factors are examined on a thoracentesis?
color protein LDH Cholesterol WBC
What are the most likely causes of lymphocytosis?
Tb (negative AFB does NOT rule out Tb)
Cancer
What is a pneumothorax?
Breach in pleura leading to exposure of pleural space to positive atmospheric pressure, air enters the pleural space*, and the lung collapses inward
What is a primary pneumothorax? What causes it?
Spontaneous pneumothorax with NO identifiable lung disease–mostly in tall thin young men
(we now know most of these have subpleural blebs)
What are the symptoms of a primary pneumothorax?
acute onset of pleuritic chest pain and dyspnea
What is a secondary pneumothorax?
Pneumothorax due to an underlying lung disease
What is an iatrogenic pneumothorax?
pneumothorax due to invasive procedures like the placement of a central line or a thoracentesis
What is a tension pneumothorax?
pneumothorax that occurs when a patient is on positive pressure ventilation that leads to a pleural breach and unidirectional air flow into the pleural space–> circulatory collapse–> impaired venous return
What are the clinical signs of a pneumothorax?
Hypotension
Hypoxemia
What does a chest X-ray of a tension pneumothorax look like?
- Collapsed lung
- Contr. mediastinal shift
- depression of diaphragm
How do you treat a tension pneumothorax?
emergent decompression with a large bore needle (followed by chest tube)
