19-G EBUS: Why, When, and How?

The introduction of endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) in 20041 has no less than revolutionized the field of diagnostic bronchoscopy. Building on the initial successful application of standard “blind” TBNA and preliminary work using radial probe ultrasound devices to better localize targets, the ability to access central lesions with real-time ultrasonographic imaging with the linear EBUS scope has resulted in bronchoscopic diagnostic rates never before possible. Excellent results from this technique have been reported for a variety of clinical indications, with randomized trials suggesting equivalence to mediastinoscopy for lung cancer staging2 and superiority over standard TBNA for sarcoidosis.3 Despite these achievements, limitations remain in certain settings. In cases of suspected sarcoidosis, overall diagnostic yield of EBUS-TBNA remains ~80%4 and on a per-node basis can be as low as 55%.3 For lymphoma, pooled results from the literature suggest sensitivity to this test at 64% (192/299 cases, unpublished data) with better performance in the setting of relapsed disease versus de novo diagnoses. In addition, as the requirements evolve for molecular profiling of malignant lesions, the ability to collect larger tumor samples may be of benefit. The vast majority of EBUS-TBNA studies has been performed with the use of 22-G needles, with more limited publications using 21-G devices. Although there is no robust evidence for differences in results between the 2, some data suggest improved results with the 21-G devices in terms of non–small-cell lung cancer subtyping and in the diagnosis of benign diseases. It is with these limitations in mind that we consider the role of a newly introduced 19-G EBUS-TBNA needle in clinical practice, but, as is often the case, the commercial availability of medical devices precedes the availability of clinical data to guide us as to their optimal application. In this issue of the JOBIP, Balwan5 describes his single-operator experience with the use of this new device in the setting of suspected sarcoidosis wherein a 93% diagnostic rate was achieved in the 15 patients studied. Of note as well is a high per-node diagnostic rate of 85%. Given the absence of a comparison group using smaller needles, the retrospective nature of the study and the relatively small sample size, one cannot make any definitive statements with regard to the 19-G needle and the diagnosis of sarcoidosis. However, such success rates are certainly in the high range of previously published EBUS data. These results are also in line with those of 2 multicenter studies wherein a diagnosis was reached in 13/14 (93%) and 61/67 (91.0%) cases of suspected sarcoidosis or lymphadenopathy that was not yet diagnosed,6,7 as well as a controlled study in an animal model of granulomatous lymphadenopathy demonstrating larger specimen size with the 19-G device.8 Early experience with the 19-G device also suggests good performance in the setting of lymphoma,6,9 cancer (including molecular testing),6,7,9 as well as in providing larger core samples in malignant cases.10 Given these early results, is it time for all EBUS bronchoscopists to jump onto the 19-G bandwagon? Until such time that comparative trials showing superiority in a particular setting are completed, it would be hard to justify any strong statements supporting the use of the device. The only published comparative trial to date could not identify a difference in diagnostic rate, although statistical power was low and inclusion criteria were not geared toward indications most likely to benefit from the larger device.11 This latter study as well as Balwan’s work exposed issues related to the use of rapid on-site cytological evaluation (ROSE) of the 19-G specimens, which had more blood contamination and were more frequently noted as inadequate (despite high final diagnostic rate, ie, false-negative ROSE). Practices that rely on ROSE may need to adapt their approach when using this needle, as an inadequate specimen reading on ROSE should not dismiss the diagnostic value of the associated specimen. The 19-G device is generally more expensive than standard needles, so that cost-effectiveness may be marginal. Some technical aspects should also be considered. The needle is more flexible than previous devices.12 Although this may be an advantage in accessing targets requiring some scope flexion, such as left paratracheal and left suprahilar lesions, this feature also requires some consideration for the operator. In particular, the needle and sheath should be extended to a minimal amount before airway wall puncture to avoid any bending of the device. For similar reasons, careful avoidance of cartilage rings is required. The use of the stylet is also mandatory, as it is a critical component of the column strength of the device necessary to penetrate the airway wall without needle damage. In addition, the device needs to be advanced through the bronchoscope with the appropriate orientation to ensure proper angle of the needle bevel. Once in the target, the operator should take care to ensure that the needle is advanced while still in the ultrasound image plane of view, as, in our experience, the needle more frequently moves off axis with potential inadvertent puncture outside of the intended target. Finally, it should be noted that studies to date have for the most part sampled larger lymph nodes, and the device may not be well suited to smaller lesions, such as may be seen during staging procedures. In view of these technical aspects, we recommend that this device be used only by experienced EBUS operators. The availability of the 19-G device is a new tool for the EBUS operator with the potential to improve our results in certain settings. Further studies will be required to determine the superiority of this device in specific clinical scenarios or for specific diagnoses. Such studies may require large sample sizes, given the relatively small incremental yield one may expect over the already high performing standard EBUS procedures. Further experience will also be needed to understand the utility—or lack thereof—of ROSE, when using this needle, and optimal protocols for cytopathologic specimen preparation. Alain Tremblay, MDCM, FRCPC, FCCP Christopher A. Hergott, MD, FRCPC, FCCPDivision of Respiratory Medicine Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW Calgary, AB, Canada T2N 4N1

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