Evaluation of Efficacy of a New Cryoprobe for Transbronchial Cryobiopsy: A Randomized, Controlled in vivo Animal Study

<b><i>Background:</i></b> Forceps biopsy (FB) is still the most popular procedure for the bronchoscopic sampling of lung tissue. However, it has limitations like inadequate sample size and crush artifacts. Cryobiopsy (CB) has been introduced to obtain bronchoscopic biopsies with improved diagnostic yield compared to FB. Limitations of CB are the need to retract the cryoprobe en bloc with bronchoscope because samples are larger than the working channel and the variations of the freezing power of the reusable CB (rCB). Therefore, 3 new disposable cryoprobes (dCB) have been developed with different outer diameters: 1.1 mm (CB11-S) that can be retracted through the working channel of the bronchoscope, 1.7 mm (CB17) and 2.4 mm (CB24n), respectively. <b><i>Objectives:</i></b> The aim was to evaluate the new cryoprobes with regard to feasibility, specimen area, specimen quality and complications. <b><i>Methods:</i></b> We compared biopsy samples of the new probes with those obtained by FB and by rCB in an in vivo (porcine) model. A flexible bronchoscope was used to perform biopsy at 4 different locations at the upper and lower lobes of the right and left lung, respectively. The biopsies were taken under fluoroscopic control. The biopsy tool and activation times were allocated randomly. Altogether 204 biopsy procedures were performed. <b><i>Results:</i></b> The sample quality of the dCB was superior to that of FB (all <i>p</i> &#x3c; 0.05) and not significantly different to the rCB sample quality. Mean specimen sample area of all CB was significantly larger compared to FB (<i>p</i> &#x3c; 0.05). The sample area of the small cryoprobe (CB11-S) was significantly smaller compared to the other CB probes (<i>p</i> &#x3c; 0.05). No severe bleedings occurred. Pneumothoraces were detected in 3 of the 7 pigs. <b><i>Conclusion:</i></b> We conclude that CB with the new single-use instruments are feasible and represent a viable option to improve the diagnostic accuracy of histopathological evaluation compared to FB.