Feasibility and safety of ultrasound-aided thoracentesis in mechanically ventilated patients

Objective: Thoracentesis in a ventilated patient is rarely performed becaus e of the risk of pneumothorax. We have evaluated the safety of this procedu re when aided by ultrasound. Design: Prospective study. Setting: Medical intensive care unit, university -affiliated hospital. Patients: 45 procedures were performed in 40 consecutive patients with ultr asound signs of pleural effusion, all mechanically ventilated. Interventions: Pleural effusion was defined on ultrasound as a collection o f fluid between parietal and visceral pleura leading to variations in inter pleural distance during breathing. When the interpleural distance was great er than or equal to 15 mm and visible over three intercostal spaces, a need le (16 or 21 G) was inserted after ultrasound localization in a patient in either dorsal or lateral decubitus. Results: No complication occurred in the 45 thoracenteses. Fluid was obtain ed in 44 of 45 procedures, thus confirming the diagnosis of pleural effusio n. The procedure was immediate (less than 10 s) in 40 of 45 cases. It was e asy (i.e., keeping the patient supine) in 22 of 45 procedures. In 44 cases where fluid was obtained, only 27 bedside radiographs revealed signs of eff usion, whereas 17 showed absence of a visible effusion. Ultrasound thus app eared more efficient than bedside X-ray in detecting pleural effusion. Conclusions: If basic rules are followed, ultrasound localization makes tho racentesis a safe, easy and simple procedure in patients on mechanical vent ilation.