The Impact of Gravity versus Suction-driven Therapeutic Thoracentesis on Pressure-related Complications: the GRAVITAS Multicenter Randomized Controlled Trial

Abstract Background Thoracentesis can be accomplished by active aspiration or drainage with gravity. We investigated whether gravity drainage could protect against negative-pressure related complications, such as chest discomfort, re-expansion pulmonary edema or pneumothorax, compared to active aspiration. Methods This prospective, multicenter single blinded randomized controlled trial allocated patients with large free-flowing effusions estimated ≥ 500 mL 1:1 to active aspiration or gravity drainage. Patients rated chest discomfort on 100 mm visual analog scales before, during, and after 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 five minutes post-procedure. Secondary outcomes included measures of discomfort and breathlessness through 48 hours post-procedure. Results One hundred forty-two patients were randomized with 140 in the final analysis. Groups did not differ for the primary outcome (mean VAS score difference 5.3 mm, 95% CI -2.4 to 13.0, p = 0.17). Secondary outcomes of discomfort and dyspnea did not differ between groups. Comparable volumes were drained in both groups but procedure duration was significantly longer in the gravity arm (mean difference 7.4 minutes, 95% CI 10.2 to 4.6, p Conclusions Thoracentesis via active aspiration and gravity drainage both appear safe and result in comparable levels of procedural comfort and dyspnea improvement. Active aspiration requires less total procedural time.