Correlation of activation time and number of passes to diagnostic yield of endobronchial ultrasound guided transbronchial nodal cryobiopsy: an initial experience

SS. Kho*^a (Dr), CS. Chai^a (Dr), NH. Ngu^a (Dr), MC. Yong^a (Dr), SK. Chan^a (Dr), ST. Tie^a (Dr)

^a Division of Respiratory Medicine, Sarawak General Hospital, Kuching, Sarawak, MALAYSIA

* bzk99@hotmail.com

Background The role of EBUS/TBNA beyond lung cancer staging is frequently limited, especially in the diagnosis of rare and benign mediastinal lesion. EBUS guided transbronchial nodal cryobiopsy (TBNC) is a novel technique in acquiring histological specimen from mediastinal lesions. Although feasibility of EBUS/TBNC had been proven in study, further technical refinement is needed to further develop this technique. We aim to assess the correlation of cryo-activation time and number of passes to the diagnostic yield of EBUS/TBNC.

Methods Retrospective review of 25 EBUS/TBNC cases performed over 10 months duration. EBUS/TBCN procedure was performed with 1.1 mm cryoprobe without rapid onsite examination.

Results The median age of our cohort was 60.0 (IQR 55.5-67.5) years old. Majority (92%) of cases were performed for diagnostic indication. Artificial airway was used in all cases (endotracheal tube 12%, rigid bronchoscope 20%, laryngeal mask airway 68%) with median procedure duration of 75 (IQR 60-90) minutes. EBUS/TBNA was performed with 22G TBNA needle in all cases prior cryoprobe insertion. 15 (60%) patients required additional incision with electrosurgery knife to facilitate cryoprobe insertion. Median 4 (IQR 3-4) passes were performed for EBUS/TBNC and was activated for a median of 10 (IQR 8-11) seconds. Overall, EBUS/TBNC recorded significantly higher diagnostic yield than EBUS/TBNA (80% vs. 52%, p<0.05) with majority comprised of malignant diseases. No major complications were encountered in all cases. Median aggregate specimen size was 7 (IQR 5-8) mm with no significant correlation with overall diagnostic yield. Longer freezing time (r_s=0.420, p<0.05) and number of cryobiopsy passes (r_s=0.442, p<0.05) was found to have strong positive correlation to higher overall diagnostic yield.

Conclusion EBUS/TBNC had better diagnostic yield than EBUS/TBNA by providing histological evidence of disease. Larger study focusing on technical refinement is highly anticipated in the future.

Disclosure of funding source(s): none