Subcutaneous emphysema (SE) was less common with the use of small-bore (SB) chest tubes compared with large-bore (LB) tubes in adults with nontraumatic pneumothoraces, based on new data from approximately 16,000 individuals presented at the Annual Conference of the American Association for Bronchology and Interventional Pulmonology.

Current guidance favors SB chest tubes (defined as ≤ 14 Fr, or approximately 2.7-4.7 mm in width) over LB chest tubes for the management of nontraumatic pneumothoraces, wrote Fouad H. Helmy, MD, pulmonology and critical care fellow at Case Western Reserve University and University Hospitals Cleveland Medical Center, both in Cleveland, and colleagues.

However, SE has not been well studied as a primary endpoint in these patients, although it can be associated with prolonged drainage, discomfort, additional radiographic imaging, and longer hospital stay, the researchers noted.

To assess potential differences in SE associated with tube size, the researchers reviewed data from the TriNetX network of 112 healthcare organizations for patients aged 18 years or older with nontraumatic pneumothoraces. They identified 24,293 patients treated with LB tubes and 8540 patients treated with SB tubes. Any patients with a history of SE, pleural effusion, pneumonia, influenza, hemothorax, thoracic trauma or procedure, or cardiac arrest within the 6 months preceding the index event (defined as chest tube insertion and pneumothorax) were excluded.

The final study population included 8427 patients in each group after propensity score matching. Outcomes were assessed between 1 and 10 days after the index event.

Overall, the primary outcome of SE occurred less frequently in the LB vs SB tube groups (370 patients vs 279 patients; odds ratio [OR], 1.33).

The secondary outcome of postprocedural empyema was similar between the groups (OR, 1.165), but the odds of hemothorax/hemorrhage, video-assisted thoracoscopic surgery, malpositioning or displacement, and all-cause mortality were lower in the SB patients (OR, 1.7919, 1.460, 2.137, and 1.916, respectively).

The findings were limited by several factors including the reliance on a database.

However, “By making SE the primary endpoint, this study addresses an important gap in the pneumothorax device literature and provides high-powered comparative estimates of an early complication that may reflect drainage performance and drive escalation of care,” the researchers concluded.

Findings Affirm Practice Shift

Over the past 15-20 years, clinicians have increasingly migrated from placing LB chest tubes with a surgical (open) technique to SB tubes placed percutaneously using the modified Seldinger technique, said David Manoff, MD, chief of pulmonary and critical care medicine at Temple University Hospital-Jeanes Campus in Philadelphia, who was not involved in the study.

“The current study adds to the body of evidence that the smaller-bore tubes are just as efficacious for the vast majority of medical indications as the larger-bore tubes with fewer complications,” said Manoff, who also serves as medical director of the Temple University Hospital-Jeanes Campus ICU.

The findings were not unexpected and support the current body of data favoring SB chest tubes, said Manoff. “I suspect that the decreased amount of subcutaneous emphysema has as much to do with the percutaneous insertion technique of the small-bore tubes vs incision and dissection with the larger-bore tubes,” he noted. “As the dilators for the small-bore tubes are, depending on the kit used, either the same diameter as the tube or perhaps 2-Fr (2/3 of a millimeter) larger than the tube, there is much greater apposition of the tube to the site with the small-bore tubes,” he said. “This also leads to less trauma of the surrounding structures with likely less hemorrhage, infection, and need for thoracoscopic surgical exploration,” Manoff added.

The current study is practice-affirming rather than practice-changing, said Manoff. The results support a limited role for LB chest tubes in managing nontraumatic pneumothoraces, while the vast majority of the pneumothoraces requiring chest tube drainage should be done using a percutaneously placed SB chest tube, he said.

Manoff identified two avenues for additional research. “Over time, we will likely see additional data looking at patient-centered outcomes with the use of large-bore vs small-bore chest tubes,” he said.

Secondly, practice has shifted sufficiently in favor of SB tubes that a prospective, randomized trial for looking at placement of LB tubes vs SB tubes would be difficult to have approved or recruit for, Manoff noted. However, “I suspect that the insertion technique was a significant contributor to the decrease in subcutaneous emphysema, though the authors’ secondary outcomes are undoubtedly also influenced by the smaller size of the tube,” he said. “As larger-bore percutaneously placed chest tubes are available, additional study of small-bore vs large-bore percutaneously placed tubes could help to shed light on which part of the difference in tubes was the major driver of the outcomes seen here,” he added.

The study received no outside funding. The researchers had no financial conflicts to disclose. Manoff had no financial conflicts to disclose.