Protocolized Thoracic Ultrasonography in Transbronchial Lung Cryobiopsies: A Potential Role as an Exclusion Study for Pneumothorax.

Background: Widespread implementation of transbronchial lung cryobiopsy (TBLCB) in the diagnostic approach to diffuse parenchymal lung disease has prompted a call for standardization of technique to optimize safety and diagnostic yield. Thoracic ultrasound (TUS) is proving effective in detecting postconventional transbronchial biopsy pneumothorax (PTX). However, TUS does not obviate the need for chest radiography (CXR) which quantifies and guides treatment of PTX. To our knowledge, this is the first experience evaluating TUS's reliability to rule-out PTX post-TBLCB in diffuse parenchymal lung disease.

Methods: Retrospective analysis of patients undergoing TBLCB. A standardized pre-TBLCB/post-TBLCB TUS was performed to detect the presence or absence of sliding lung (SL). TUS' findings were then compared with CXR performed at 1 hour after TBLCB.

Results: A total of 24 patients' records reviewed. In total, 21 of 24 patients had SL in all lung zones on TUS before and after TBLCB, with a negative CXR for PTX in all 21 patients. The negative predictive value was 100% (95% confidence interval, 84%-100%). Three patients did not have SL in all lung zones on TUS, of which 2 showed the absence of SL in all lung zones on both pre-TBLCB and post-TBLCB TUS, with negative CXR for PTX. 1 of the 3 showed SL in all zones pre-TBLCB and in only 2 zones post-TBLCB. CXR confirmed PTX in this 1 patient.

Conclusion: Our study demonstrates a 100% negative predictive value for the exclusion of PTX via TUS' verification of SL. The practical value of TUS post-TBLCB may lie in its application as a rule-out study, thereby avoiding CXR.