Pleural Diseases Flashcards
Give conditions which can pleural effusions by the following mechanisms:
- Increase in hydrostatic pressure
- Decrease in oncotic pressure
- Diaphragmatic defects -> is this considered transudate / exudate?
- Congestive heart failure -
#1 cause - Nephrotic syndrome (decreased serum proteins)
- Liver disease, ascites
-> transudate if simple liver disease
-> exudate if associated with abdominal infection (i.e. SBP, pancreatitis)
What processes can cause direct passage of fluid into the pleural cavity?
- Rupture of thoracic duct
- Rupture of esophagus
- Iatrogenic from central catheter insertion
How can malignancies and pneumonia cause pleural effusion?
Malignancy - capillary proliferation and impaired lymphatic drainage
Pneumonia - inflammatory process allows fluid to leak into pleural cavity
What processes cause an exudate in the pleural effusions?
Pleural inflammation, infection, or malignancy -> high protein pulmonary edema (i.e. pneumonia, PE, malignancy)
Leaking from surrounding tissue -> mediastinum if esophagus ruptures, or chylothorax
Abdominal infections
What are the symptoms of pleural effusion?
Symptoms - dyspnea (decreased gas exchange, possible lung collapse) and pleuritic chest pain (worse with inspiration)
What are the clinical signs of pleural effusion?
Dullness to percussion, absence of fremitus, diminished / absent breath sounds, friction rub
Also signs & symptoms of underlying etiology of pleural effusion
What is the most common way pleural effusion is diagnosed? What does this help differentiation it from?
Chest X-ray showing a layer of fluid in the pleura if the patient is in left lateral decubitus position
Atelectasis & consolidation will not move in the pleural cavity like this.
Note: Loculated (cystic) effusion will not be able to move like this
What is the method of choice to locate pleural effusion in thoracentesis?
Chest ultrasound
When is thoracentesis NOT done for draining pleural effusions? Why?
Whenever the clinically suspected reason is transudative: congestive heart failure, low protein, or cirrhosis of liver
-> resulting negative intrapleural pressure will cause more fluid to be pulled out of vessels
When is thoracentesis generally indicated?
All exudative causes - want to prevent fibrotic adhesions in pleura
Also - in presence of CHF or cirrhosis if there is unexplained infection (evidence of inflammatory process)
What are absolute contraindications for thoracentesis?
Lack of patient cooperation, severe coagulopathy, hemodynamic instability, local chest wall infection (can spread the infection inside)
What are possible complications of thoracentesis?
Pneumothorax Hemorrhage Syncope Infection Puncture of spleen or liver Re-expansion of pulmonary edema if >1L removed (negative intrapleural pressure)
Where is thoracentesis typically done?
One interspace below the fluid level, above the rib, in midscapular line (use ultrasound for guidance).
Patient should be sitting up
What tests is the pleural fluid typically sent for?
Cell count and differential
Chemistry: protein, glucose, pH, LDH
Culture: Gram stain and AFB stain with cultures
Cytology for malignant cells
What additional tests should be ordered on the pleural fluid if there is clinical suspicion of the following causes:
- Pancreatitis
- Chylothorax
- Cholethorax
Pancreatitis - amylase
Chylothorax - triglycerides:
>110 mg/dL is diagnostic (should appear milky white)
Cholethorax - bilirubin
What are the criteria for calling an effusion an exudate: think protein and LDh
Any one of the following:
Pleural fluid protein is > 1/2 of serum protein
Pleural fluid LDH is >0.6 serum LDH
If no serum drawn: Pleural fluid is >2/3 upper limit of normal for serum LDH
What are the criteria for cholesterol and protein absolutely to cause pleural effusion an exudate without serum to compare?
Pleural fluid cholesterol > 45 mg/dL
Pleural fluid protein > 2.9 g/dL
How might you classify an effusion due to CHF as a transudate even if it meets normal criteria for an exudate and why?
Serum-pleural fluid albumin difference is >1.2 g/dL
Because protein is not truly leaking, serum is just relatively more concentrated due to diuresis in these patients
What can cause a low protein pleural effusion with high glucose?
Peritoneal dialysis
-> high glucose content in diasylate fluid
What connective tissue diseases can cause pleural effusion and is it a transudate or exudate?
Rheumatoid pleurisy, SLE pleuritis
-> exudate
What do you base on your differential diagnoses on if nothing obviously gives you diagnosis of your pleural fluid?
Cell count: i.e. neutrophils, lymphocytes, eosinophils, RBCs
Glucose
pH
LDH
High amylase
How do parapneumonic effusions (associated with pneumonia) typically resolve, and what is typical vs complicated?
Usually resolve spontaneously
Typical: pH>7.2, glucose >60, gram stain negative
-> not associated with loculation, Abx alone is fine
Complicated: pH <7.2, glucose <60, gram stain positive
-> chest tube and thrombolytics may be needed in addition as effusion becomes loculated
What is empyema and what is the treatment?
A complication of parapneumonic effusion, frank pus is obtained by thoracentesis
Need antibiotics and chest tube, with probable surgery to prevent long-term sequellae
What are the most common malignant effusions of the lungs? What will lymphocytes, glucose, LDH, and cytology show?
Lung or breast cancer
Lymphocytes - high
Glucose - low
LDH - high
Cytology - may be initially negative but does not rule out, repeat.
If tuberculosis is highly suspected as causing effusion, but cannot be stained or cultured, what level is measured as a surrogate?
Adenosine deaminase level (>40 U/L minimum)
What is diagnostic of hemothorax?
Hematocrit of pleural fluid is >50% of serum hematocrit
What are the nontraumatic causes of hemothorax?
Anticoagulation, malignancy, aneurysm, thoracic endometriosis (very rare), spontaneous pneumothorax
When is pleural biopsy done and how is it generally done nowadays?
If diagnosis remains unconfirmed after thoracentesis
Done via open biopsy by thoracic surgeons
Why is tension pneumothorax a medical emergency? How is it diagnosed?
Can cause low blood pressure due to decreased venous return
diagnosis generally by CXR
What is the difference between tension pneumothorax and spontaneous pneumothorax?
Spontaneous - much rarer, occurs in a patient without underlying disease, and air enters pleura from alveoli
Tension - generally due to trauma or iatrogenic, air enters pleura from thru chest will
How do you treat small vs large pneumothorax?
Small - give patient O2 and monitor by CXR, nitrogen should reabsorb thru alveoli
Large - drain by chest tube. If acute cardiopulmonary collapse, use needle aspiration then chest tube
How is recurrent pneumothorax treated?
Pleurodesis - inject talc into pleural space to create inflammation and closure of pleural space
