Focused lung ultrasound for diagnosing iatrogen pneumothorax after transbronchial lung cryobiopsy

Background: Transbronchial lung cryobiopsy (TBCB) is a diagnostic tool for patients suspected of interstitial lung disease (ILD). Iatrogen pneumothorax (PTX) is a common and important TBCB complication. This study aimed to assess the diagnostic accuracy of post-procedure focused lung ultrasound (FLUS) for diagnosing PTX in ILD patients undergoing TBCB. Methods: In patients suspected of ILD undergoing TBCB, FLUS of the anterior surface of the chest was performed immediately before and after the TBCB procedure prior to extubation. Presence of lung point was used as a definite sign of PTX. Change from presence to absence of lung sliding (but no lung point) following the procedure was used as a sign of possible PTX. Chest x-ray was performed routinely 2 hours after the procedure in all patients and used as reference test. Results: Eighty-three consecutive patients were included in the study. The reference test identified PTX in ten patients (12.1%). Six of these were treated with drainage and four treated conservatively. FLUS identified none with possible PTX and two with definite PTX, one of whom had a large PTX requiring immediate treatment. The diagnostic accuracy of FLUS for diagnosing PTX was: sensitivity 20% (95%CI: 2.52-55.6%), specificity 100% (95%CI: 95-100%), positive predictive value 100% (95%CI: 15.8-100%), negative predictive value 90% (95%CI: 81.2-95.6%). Conclusion: FLUS following TBCB procedure can be used safely to identify patients needing immediate treatment for PTX. It can, however, not be used to rule out development of PTX with need of treatment later in the post-procedure period.