Safety and Tolerability of Vacuum Versus Manual Drainage During Thoracentesis: A Randomized Trial

Pleural effusions may be aspirated manually or via vacuum during thoracentesis. This study compares the safety, pain level, and time involved in these techniques.

We randomized 100 patients receiving ultrasound-guided unilateral thoracentesis in an academic medical center from December 2015 through September 2017 to either vacuum or manual drainage. Without using pleural manometry, the effusion was drained completely or until the development of refractory symptoms. Measurements included self-reported pain before and during the procedure (from 0 to 10), time for completion of drainage, and volume removed. Primary outcomes were rates of all-cause complications and of early termination of the procedure with secondary outcomes of change in pain score, drainage time, volume removed, and inverse rate of removal.

Patient characteristics in the manual (n=49) and vacuum (n=51) groups were similar. Rate of all-cause complications was higher in the vacuum group (5 vs. 0; P=0.03): pneumothorax (n=3), surgically treated hemothorax with subsequent death (n=1) and reexpansion pulmonary edema causing respiratory failure (n=1), as was rate of early termination (8 vs. 1; P=0.018). The vacuum group exhibited greater pain during drainage (P<0.05), shorter drainage time (P<0.01), no association with volume removed (P>0.05), and lower inverse rate of removal (P≤0.01).

Despite requiring less time, vacuum aspiration during thoracentesis was associated with higher rates of complication and of early termination of the procedure and greater pain. Although larger studies are needed, this pilot study suggests that manual aspiration provides greater safety and patient comfort.