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<h4>Background</h4>Thoracentesis can be accomplished by active aspiration or drainage with gravity. This trial investigated whether gravity drainage could protect against negative pressure-related complications such as chest discomfort, re-expansion pulmonary edema, or pneumothorax compared with active aspiration.<h4>Methods</h4>This prospective, multicenter, single-blind, randomized controlled trial allocated patients with large free-flowing effusions estimated ≥ 500 mL 1:1 to undergo active aspiration or gravity drainage. Patients rated chest discomfort on 100-mm visual analog scales prior to, during, and following drainage. Thoracentesis was halted at complete evacuation or for persistent chest discomfort, intractable cough, or other complication. The primary outcome was overall procedural chest discomfort scored 5 min following the procedure. Secondary outcomes included measures of discomfort and breathlessness through 48 h postprocedure.<h4>Results</h4>A total of 142 patients were randomized to undergo treatment, with 140 in the final analysis. Groups did not differ for the primary outcome (mean visual analog scale score difference, 5.3 mm; 95% CI, -2.4 to 13.0; P = .17). Secondary outcomes of discomfort and dyspnea did not differ between groups. Comparable volumes were drained in both groups, but the procedure duration was significantly longer in the gravity arm (mean difference, 7.4 min; 95% CI, 10.2 to 4.6; P < .001). There were no serious complications.<h4>Conclusions</h4>Thoracentesis via active aspiration and gravity drainage are both safe and result in comparable levels of procedural comfort and dyspnea improvement. Active aspiration requires less total procedural time.<h4>Trial registry</h4>; No.: NCT03591952; URL:

Original publication




Journal article



Publication Date





702 - 711


Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN; Department of Thoracic Surgery, Vanderbilt University School of Medicine, Nashville, TN; Department of Veterans Affairs Medical Center, Nashville, TN.


Interventional Pulmonary Outcomes Group, Humans, Pulmonary Edema, Pleural Effusion, Pneumothorax, Dyspnea, Postoperative Complications, Chest Pain, Drainage, Suction, Single-Blind Method, Gravitation, Aged, Middle Aged, Female, Male, Operative Time, Thoracentesis, Pain, Procedural