Uncomplicated parapneumonic effusion vs Comlicated parapneumonic effusion vs Empyema

As a part of Pulmonary team, we were consulted by ER to evaluate a 72 y.o male with no significant PMH, presented to ER with cough, green sputum, fevers, chills, exertional dyspnea.  He was diagnosed with HCAP and severe sepsis in ER. CXR showed a moderate sized pleural effusion. Appropriate IVF and antibiotics were initiated. 

1. Does the patient need a diagnostic thoracentesis?
2. Does he need a chest tube?
3. What is the difference between Uncomplicated parapneumonic effusion vs Comlicated parapneumonic effusion vs Empyema?

This patient ended up getting diagnostic thoracentesis - we were unsuccessful as we could not get any fluid for diagnostic eval due to loculated effusion and septations (visible on ultrasound lung). Patient was referred to IR team for Fluoro guided Chest tube placement. Fluid revealed frank pus. However first day drainage was <100ml purulent effusion. So, the patient received tPA and DNAase via the chest tube to break down the septations and improve drainage. We requested the IR docs not to manage the fibronylitics. We preferred to do it ourselves. 

What is the difference between Uncomplicated parapneumonic effusion vs Comlicated parapneumonic effusion vs Empyema?

• An uncomplicated parapneumonic effusion has "exudative" chemistries, normal pH and glucose, and negative cultures. 
• A complicated parapneumonic effusion typically has "exudative" chemistries, a low pleural pH (pH <7.20), a low glucose, and is often loculated. 
• Empyema fluid typically looks like pus and organisms are visible on Gram stain, although cultures may be negative

Who would qualify for a diagnostic thoracentesis?

• In general, all parapneumonic effusions, EXCEPT those that are free flowing and layer less than 10 mm on a lateral decubitus film, should be sampled (diagnostic) by thoracentesis. 

Who would qualify for a Chest tube placement?

• In patients with a large, loculated, or complicated parapneumonic effusion or empyema. 

Pearls:

• CT or ultrasound-guided placement of multiple tubes may be needed when pleural loculations prevent adequate drainage by a single tube. 
• In patients with a thoracic empyema - tube thoracostomy and video-assisted thoracoscopic surgery (VATS) with debridement are acceptable. The latter may be preferred in patients with multiple loculations and a thick pleural peel. 
• When tube thoracostomy is used for initial drainage of an empyema, a chest CT scan should be obtained within 24 hours after chest tube placement to document appropriate placement of the tube and assess drainage. 
• For patients who do not have good drainage of empyema fluid from a well-placed chest tube, administer a combination of TPA 10 mg and deoxyribonuclease (DNase) 5 mg, twice daily for three days. IR team does a different regimen that is not effective and not evidence based. So do not let IR team manage the fibrinolytics. 

Trivia: 

• The only pleural effusion with a trasudative chemistry but low pH : URINOTHORAX. 
• Red tinged effusion is likely a hemothorax when the pleural fluid hematocrit / blood hematocrit ratio is >50%
• Chylothorax  - triglyceride level >110. 
• Lights criteria can be false positive when a patient with transudative effusion gets lasix. 

Uptodate reference