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Safety and Feasibility of a Sheath Cryoprobe for Bronchoscopic Transbronchial Biopsy: The FROSTBITE Trial

Background: Bronchoscopic lung biopsy is typically performed using transbronchial forceps. However, this method is limited by small sample size and presence of crush artifact. Cryobiopsy offers the potential to overcome these limitations with larger artifact-free samples but has not been widely adopted due to concerns over increased rates of bleeding and pneumothorax. A new, smaller 1.1-mm cryoprobe has been developed that operates in a similar fashion to forceps, though the safety profile of this cryoprobe has not yet been prospectively studied. Objective: The aim of this study was to investigate the safety of transbronchial biopsy using a novel 1.1-mm cryoprobe. Methods: This prospective, single-arm study enrolled patients referred for transbronchial biopsy. All procedures were performed using the 1.1-mm cryoprobe with oversheath. The primary outcome was the composite of significant complications related to the cryobiopsy procedure (bleeding Grade ≥3, pneumothorax Grade ≥2, and respiratory failure). Bleeding and pneumothorax were graded according to previously published scales. Results: Fifty participants from two academic medical centers underwent transbronchial cryobiopsy. Indications for biopsy included evaluation of lung transplant allograft (50%), diffuse lung disease (44%), and pulmonary parenchymal lesion (6%). There were two pneumothoraces (4%), neither of which required aspiration or chest tube placement. There were no Grade 3 or 4 bleeding events. Mild bleeding (Grade ≤2) was observed in 25 cases (50%). No complications occurred that met the a priori primary outcome of bleeding Grade ≥3, pneumothorax Grade ≥2, and respiratory failure. Conclusions: Transbronchial cryobiopsy using a 1.1-mm cryoprobe is feasible with an acceptable safety profile.