Pleural effusions in critically ill patients.

Pleural effusions (PEs) are common in critically ill patients mainly as a consequence of severe cardiopulmonary disorders frequently encountered in these patients. Their impact on the pathophysiology of acute respiratory failure remains unknown. They are usually small and uncomplicated transudates that are easily overlooked on a supine portable chest X-ray and do not require drainage or infectious exudates that always require thoracocentesis. The diagnosis of PEs in critically ill patients has been revolutionized with the advent of chest ultrasound allowing easy bedside quantification of pleural fluid and making thoracocentesis a safe procedure especially in high-risk patients on mechanical ventilation. CT provides a much more accurate evaluation of the size and location of PEs and is extremely helpful in the guidance of catheters into loculated fluid collections. Hemothorax in critically ill patients is usually related to trauma or surgical interventions and requires early drainage and possibly surgical exploration.