Pleural Effusion in Critically Ill Patients

Pleural effusion in intensive care patients is frequently diagnosed. Main factors causing pleural effusion in critically ill patients are fluid overload, heart failure, and pneumonia. Thoracic ultrasound (TUS) may be of help in discriminating the nature of the pleural effusion, between transudate and exudate, but a definitive diagnosis is not always possible. The Light criteria are still the landmark in distinguishing the characteristics of the effusion. In the visualization of pleural effusion, TUS is more accurate than supine radiography and is similarly accurate as a computed tomography scan. In estimating the amount of pleural effusion by TUS, Balik’s formula is one of the most used for its simplicity. Clinical symptoms, the amount of pleural effusion and gas exchange are the most important aspects to decide treatment and drainage. However, draining even a very small pleural effusion can also be important for diagnostic purposes. The guideline of the British Thoracic Society on pleural diseases recommends TUS for guiding thoracentesis or chest tubes placement to improve the safety of invasive treatments, particularly in ventilated, critically ill patients. Recently, smaller-bore tubes using the modified Seldinger technique demonstrated to be effective for fewer related complications.