Data from the National Lung Cancer Screening Trial continue to generate significant interest in advanced diagnostic procedures in the chest.1 Electromagnetic navigational bronchoscopy (ENB) was designed to extend bronchoscopy to the more peripheral airways using a combination of hardware-based and software-based solutions. Overall, the diagnostic yield of navigational bronchoscopy is significantly higher when compared with traditional bronchoscopy in the diagnosis of peripheral pulmonary nodules.2 For the most part, the data suggest that lesion size and location—at least to a point—do not have a significant impact on the procedural yield. The data also seem to indicate that diagnostic yields do improve in the presence of a bronchus sign leading to the lesion.3 Nevertheless, the data on yield rates around other factors such as the use of fluoroscopy or deeper levels of anesthesia remain somewhat uneven. The article by Brownback and colleagues4 in this issue of the Journal of Bronchology & Interventional Pulmononlogy examines the yield of sampling tissue from peripheral pulmonary nodules using ENB as a consequence of a number of different factors including the bronchus sign, lesion location, and size. Their results indicate that the technique demonstrates an acceptable diagnostic yield with a reasonable safety profile and the results are comparable to previous published data. However, and somewhat dissimilar to previously published data, it also suggests that the yield with ENB may not be affected by the presence or the absence of a bronchus sign, which had previously been shown to increase yield. Their data also suggest that the use of fluoroscopy and general anesthesia may result in improved yield rates. Data on the use of fluoroscopy are inconsistent. Fluoroscopy has been used in most studies of ENB to verify the biopsy site and the distance from the pleura because of the concern that the extended working channel (EWC) might be displaced when different tools are introduced.2,5–8 Nevertheless, a more recent study with ENB was conducted without fluoroscopy, and authors suggested that there was no effect on the yield.9 To date, there is no definitive study that addresses whether the addition of fluoroscopy to ENB has a significant impact on the safety or the diagnostic yield. Difficult-to-reach lesions such as those that require movement of the EWC in 2 planes at a distance from the scope can lead to significant catheter distortion, with the potential for considerable catheter displacement with repeated placement of tools or with respiration. Although one can speculate on why the addition of fluoroscopy might result in an increased yield, we suspect that a definitive answer will remain elusive. Nevertheless, at our institution, we do use fluoroscopy largely to confirm that there has been no displacement of the EWC when alternating between biopsy tools and when the catheter path is tortuous. Data on yield rates with ENB relative to different levels of anesthesia represent an emerging area of study. Propofol, one of the most widely used sedatives for achieving general anesthesia, has been shown to be safe and effective when compared with the combination of benzodiazepines and opioids used for conscious sedation during bronchoscopy, with the added benefit of faster recovery and return to baseline mental status. Moreover, this is in the context of no appreciable difference in adverse events including hypoxia.10 In addition, the use of nurse-administered propofol sedation for bronchoscopy without the support of an anesthesiologist has recently demonstrated a favorable safety profile with an overall low complication rate.11 From a practical standpoint, deeper levels of sedation, especially in the context of administration by anesthesia personnel, would seem to allow the proceduralist to focus on the task at hand, maximizing the ability to navigate, all while being able to titrate to a more effective and appropriate level of anesthesia. Despite this, there has been no direct comparison of general anesthesia versus conscious sedation with the use of ENB. Similar to the emergence of procedures in other fields of medicine, it is not surprising that the data on ENB are somewhat inconsistent. Although this study is a valuable contribution, perhaps its most critical aspect is to highlight the need to transition and expand to larger, multi-institutional approaches to evaluate these issues.
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Feb 1, 2013
Trevor J Szymanski + 5
Open Access
