We went through a case of an elderly gentleman who presented with productive cough, shortness of breath, leukocytosis, and a large left pleural effusion.

In the evaluation of a pleural effusion in the setting of a suspected pneumonia, pleural fluid sampling is imperative. Parapneumonic effusion is an umbrella term for any type of pleural effusion in the setting of an adjacent pneumonia and can be divided into uncomplicated/simple and complicated effusions.

Uncomplicated effusions are usually small (i.e. costophrenic angle blunting, <10mm on lateral decubitus radiograph, or estimated volume <100mL). If they are sampled, they do not contain evidence of infection (negative gram stain/culture, normal glucose, and pH >7.2). These do not require treatment separate from treatment of the underlying pneumonia. However, they can become infected and if clinical improvement is not observed in 2-4 days, repeat imaging should be performed to check if the effusion has increased in size.

Complicated effusions are any effusions that are infected, including empyemas (pus within the pleural cavity). Typical features of a complicated pleural effusion include loculations, large size (>0.5 hemithorax), thickened pleura, split pleura sign on CT, and sepsis. These effusions have exudative features upon pleural fluid sampling, high WBC count (usually neutrophilic if bacterial), pH <7.2, and glucose <60. They should be promptly treated with antibiotics with coverage of anaerobes as well as Strep species, usually a 3rd generation cephalosporin with Flagyl OR Augmentin. Drainage should also be attempted as soon as possible with chest tube placement.

It was previously thought that large bore chest tubes were the treatment of choice, but according to the MIST1 trial, smaller catheters had much improved pain scores without worse outcomes, although they did have more frequent blockages, which can be alleviated by sterile saline flushes Q6h.