External Suction and Fluid Output in Chest Drains After Lobectomy: A Randomized Clinical Trial

Even when air leakage has ceased completely after lobectomy, chest drains are often not removed because of high fluid output. Accepted thresholds for removal vary between institutions but typically range between 200 and 500 mL/d. There is little knowledge whether external suction influences the amount of fluid.

We randomly assigned (1:1) 106 patients who underwent lobectomy to either low (-5 cm H₂O) or high (-20 cm H₂O) external suction using an electronic chest drainage system. Only one chest drain was allowed, and we used strict algorithms for chest drain removal, which was delegated to staff nurses: air leakage less than 20 mL/min for 6 hours regardless of fluid output, provided it was serous. The primary end point was fluid output after 24 and 48 hours.

Mean fluid output was significantly higher with high suction after both 24 (338 ± 265 mL versus 523 ± 215 mL) and 48 hours (616 ± 366 mL versus 1067 ± 387 mL (p < 0.001). Repeated measure analysis (mixed model) demonstrated that in addition to suction level the surgical approach (video-assisted thoracoscopic surgery/thoracotomy, p = 0.04) and affected lobe (upper/lower, p = 0.001) were significant predictors of fluid production.

Increased suction levels lead to increased fluid output. Thoracotomy and lower lobectomy are associated with increased fluid output in chest drains, which should be taken into consideration if algorithms for chest drain removal include an upper limit of fluid output.