Work

Effects of cryo-parameters and retrieval methods on specimen acquisition and quality for ultrathin cryoprobe transbronchial cryobiopsy in porcine models

Year: 2026

Type: article

Abstract: Ultrathin cryoprobes enable direct retraction through the working channel during transbronchial cryobiopsy. However, key factors of biopsy performance remain insufficiently characterized. This study evaluates cryo-parameters and retrieval methods across different working channels in a porcine model to define parameter strategies that balance specimen acquisition, quality and complication risk. Transbronchial cryobiopsy using an ultrathin cryoprobe under different cryo-parameters was compared with standard forceps biopsy (sFB) in ex vivo and in vivo models. Biopsy approaches were classified into five groups: P290 (BF-P290, cryoprobe retracted through 2.0 mm diameter working channel), EWC (BF-1TQ290 combined with a 2.0 mm diameter extending working channel (EWC), cryoprobe retracted through the EWC), 1TQ290-IN (BF-1TQ290, cryoprobe retracted through 3.0 mm diameter working channel), 1TQ290-OUT (BF-1TQ290, cryoprobe retracted en bloc with the bronchoscope), and sFB (standard forceps biopsy with BF-1TQ290). Acquisition rates, specimen quality and complications were assessed. In ex vivo experiments at 55 and 60 bar, a 3 s cryo-activation time was sufficient to produce specimens of greater size than those obtained with sFB. In vivo, cryo-activation times of 3–7 s achieved acquisition rates > 60% across all groups. At 9 s, acquisition rates declined to < 60% for EWC and P290, whereas the 1TQ290-IN and 1TQ290-OUT groups maintained rates > 60%. Except for the EWC group at 3 s, all groups had greater specimen weight, macroscopic cross-sectional areas, and microscopic section areas than sFB ( P < 0.05). No severe complications (grade ≥ 3 bleeding) occurred; grade 2 bleeding and pneumothorax were predominantly observed in the 1TQ290-IN and 1TQ290-OUT groups at cryo-activation times 7 and 9 s. For ultrathin cryoprobe transbronchial cryobiopsy with retraction through the EWC, a cryo-activation time of 5–7 s appears to yield increased specimen size compared with sFB, while maintaining a high specimen acquisition rate (> 60%) and procedural safety. For withdrawal via P290 and 1TQ290 bronchoscope’s working channels, a 3–7 s appears to provide a favorable balance between specimen acquisition rate, quality and procedural safety.

Source: BMC Pulmonary Medicine

DOI: 10.1186/s12890-026-04677-2