Diagnostic yield of transbronchial lung cryobiopsy in interstitial lung diseases.

Surgical lung biopsy (SLB) is still considered the gold standard procedure to obtain histology in interstitial lung diseases (ILD), the final diagnosis being decided on the basis of multidisciplinary assessment. The availability of a histological pattern may be very important in reaching diagnosis, predicting outcome and responding to treatment. There has been an increasing interest on transbronchial cryobiopsy (TCB) in the diagnosis of ILD because it presents fewer risks and complications than SLB and has a diagnostic yield superior to conventional transbronchial lung biopsy. Larger, better preserved fragments and fewer artifacts justify the greater diagnostic yield (versus conventional transbronchial lung biopsy). The aim of this work was to evaluate the diagnostic yield of TCB. All patients with suspected ILD requiring histological characterization which had been previously decided in a multidisciplinary meeting (MDM) and who underwent TCB between 05/2014 and 12/2016 were consecutively recruited into this prospective study. According to the standard of care protocol in our institution patients were required to have a pO2 ≥ 60 mmHg under oxygen delivery up to 2 l/min, forced vital capacity ≥50% (predicted) and diffusing capacity of carbon monoxide ≥40% of reference. Patients with hemoglobin <8 g/dL, severe pulmonary hypertension and unstable heart disease were excluded. All anticoagulant/antiplatelet therapies were discontinued before the procedure as per the BTS guidelines. Before the procedure, risks and possible complications were explained to each patient and informed consent was obtained. All procedures were performed under general anesthesia and jet ventilation. The TCB was performed by a pulmonologist with experience in interventional bronchoscopy. After intubation with a rigid tracheoscope (Storz ® ), a videobronchoscope was advanced to the desired segment (previously identified in high resolution computed tomography) and a flexible cryoprobe (2.4 mm, ERBE ® ) was introduced through the videobronchoscope into the bronchial segment under fluoroscopic guidance. After confirming correct positioning, a freezing time of 5 s was applied. Then, the bronchoscope and cryoprobe were removed as a single unit and a bronchial blocker baloon (Olympus ® B5-2c), previously placed in the segment was inflated, in order to prevent hemorrhage. The freezing agent used was nitrous oxide until June/2016 and after that carbon dioxide. Patients were kept under observation for 2 h after the procedure and had a chest X-ray. They were discharged if no complications occurred. Statistical analyses were performed using SPSS 20.0. All variables were tested for normality using Kolmogorov--Smirnov test. Continuous variables with normal distributions were expressed as means ± standard deviation. Continuous variables with non-normal distributions were summarized as medians (interquartile range). Categorical variables were expressed as numbers (percentages) Table 1 Patients’ characteristics.