The SEQUENCE Trial: Should Endobronchial Ultrasound QUeue bEfore or eNsuing to robotiC-assisted Bronchoscopy for pEripheral Pulmonary Nodule Biopsy?

Robotic-assisted bronchoscopy (RaB) has afforded proceduralists the ability to accurately reach the periphery of the lung for biopsy of pulmonary nodules. This has paved the way for patients to undergo both biopsy of a peripheral nodule and a staging linear endobronchial ultrasound (EBUS) in the same anesthesia event, promoting quicker throughput from discovery of a lesion to guideline-adherent treatment. Further, introduction and mainstream utilization of cone-beam CT (CBCT) has provided the bronchoscopist the ability to refine needle position with tool-in-lesion confirmation. While there are no randomized clinical trials promoting efficacy of RaB and CBCT in comparison with other bronchoscopic methods, in single center retrospective studies, diagnostic yield has consistently proven to be in the 70-85% range, superior to prior technologies.

One of the limitations of utilization of RaB and CBCT is the detrimental effect that atelectasis plays in the bronchoscopy procedure. This can lead to false positive radial EBUS (rEBUS) signals and non-diagnostic procedures. This incidence of atelectasis has been evaluated prospectively, using a protocol featuring 8-10 cmH2O of PEEP and limiting hyperoxia, and results suggest this ventilator strategy does an adequate job preventing intraprocedural lung collapse. However, this study only evaluated incidence of atelectasis and did not elaborate on its impact on diagnostic yield.

Further unknown is the optimal sequence of performance of RaB and a staging linear EBUS in patients with a radiographically normal mediastinum. Starting with either the RaB or Linear EBUS both have their pros and cons. The benefit to performance of a linear EBUS first is the potential to obviate the need for peripheral nodule biopsy by obtaining rapid, on-site pathologic feedback of occult nodal disease, reducing some of the risk of the procedure (i.e. bleeding and pneumothorax). Conversely, the pitfalls to performing linear EBUS first is the possible contribution of atelectasis resultant of the increased time from intubation to peripheral nodule biopsy, blood in the airway causing bronchospasm, and resorption atelectasis from hyperoxia. There are no prospective data evaluating this in a randomized fashion, but one Monte Carlo simulation (with assumption of diagnostic yield from navigational bronchoscopy of 70% when performed first and 60% when performed second) suggested a higher diagnostic yield and less need for repeat procedure in the navigation first group, despite a 10% assumption of occult nodal disease.

As outlined in the specific aims above, the overarching goals of this study are to assess in a multicenter, randomized clinical trial performed by members of the Interventional Pulmonary Outcomes Group (IPOG), whether sequence of staging EBUS plays a role in diagnostic yield, incidence of atelectasis, and safety outcomes in patients undergoing RaB.