Recommendation of Combination of Radial Endobronchial Ultrasound With Virtual Bronchoscopic Navigation

The diagnostic yield of transbronchial biopsy (TBBx) for peripheral pulmonary lesions (PPLs), particularly those measuring 2 cm or smaller, is very low (34%).1 Generally, transthoracic needle aspiration (TTNA) is considered for these lesions, but its complications are more common when compared with those of TBBx. Application of TTNA in chronic obstructive pulmonary disease (COPD) patients is even less ideal as the risk for pneumothorax is higher and may result in negative outcomes (prolonged air leak, increased length of stay, etc.). The use of radial-probe endobronchial ultrasound (R-EBUS) to guide TBBx improves the diagnostic yield, with a reported sensitivity of 73%.2 This technique is now recommended by the ACCP lung cancer guidelines.1 In the study reported by Georgiou and colleagues, the outcomes and complications of use of R-RBUS among advanced COPD patients were retrospectively investigated. The prevalence rate of pneumothorax and acute respiratory failure was 2.1% and 10.6%, respectively.3 Incidentally, in a large-scale survey involving 60,275 patients with PPLs undergoing bronchoscopic procedures without R-EBUS, the reported incidences of pneumothorax and acute respiratory failure were 0.44% and 0.04%, respectively, with an overall complication rate of 1.55%.4 Hayama et al5 reported an R-EBUS-associated complication rate of 1.3%, and an incidence of pneumothorax of 0.8%. No clear change in the incidence of complications due to the addition of R-EBUS was encountered. On the basis of the findings of the present study, the use of R-EBUS is considered safe in COPD patients undergoing TBBx for the diagnosis of PPLs. The incidence of complications remains lower as compared with that associated with TTNA, although it may be slightly higher than that in non-COPD patients. In addition, the present study shows an overall diagnostic yield of combined use of TBBx and R-EBUS of 63%. For lesions 2 cm or smaller, the diagnostic yield was 46%.3 Although R-EBUS is an effective method for the localization of PPLs, guiding the probe to the smaller lesion could be challenging. Under such circumstances, use of navigational bronchoscopy could be useful. Modern-day navigational bronchoscopy includes virtual bronchoscopic navigation (VBN)6 and electromagnetic navigation (EMN).7 Some investigators use EMN when the lesion cannot be identified by R-EBUS,3 but its routine use is not universally applicable because of cost constraints. It has been demonstrated that the results obtained using VBN are equivalent to those obtained using EMN,6,7 and the use of R-EBUS further adds to the outcomes. Ishida et al8 reported in a multicenter randomized controlled trial that use of VBN improves the diagnostic yield of flexible bronchoscopy from 67.0% to 80.4% for lesions 3 cm or smaller. The yield for lesions 2 cm or smaller was 75.9%. These rates appear to be higher than those reported by Georgiou et al3 in the present study. In the present study, frequency of use of the virtual bronchoscopy pathway and EMN and related results have not been described. In another study reported by the same group, the bronchial routes to lesions were routinely investigated by virtual bronchoscopy pathway. The diagnostic yield for PPLs when combined with R-EBUS was 54.8%, although further improvement in the diagnostic yield with the addition of EMN was nonsignificant.9 It is obvious that VBN should be performed to optimize the yield of TBBx even when performed using R-EBUS guidance to localize the lesion. In addition, to increase the diagnostic yield, it is important to identify the positional relationship between the lesion and the involved bronchus on computed tomography and confirm it on virtual bronchoscopic images. Furthermore, the effectiveness of ultrathin bronchoscopy in combination with R-EBUS and VBN has been shown in a multicenter randomized controlled trial. Use of R-EBUS is also possible through an ultrathin bronchoscope. In a recent study using a 3-mm-outer-diameter scope with an R-EBUS and VBN, the diagnostic yield of flexible bronchoscopy for lesions measuring 3 cm was 74%.10 The combination of R-EBUS, VBN, and ultrathin bronchoscopy seems to be the most promising methodology in the diagnosis of PPNs. The procedure also seems to be less time-consuming.8 Although the relationship between the examination time and complications is unclear, considering that respiratory failure is a potential complication of bronchoscopy among COPD patients,3 a reliable and safe diagnostic method of shorter duration is highly desirable. I am surely in favor of TBBx utilizing R-EBUS guidance in combination with VBN among COPD patients presenting with peripheral pulmonary nodules.