We retrospectively reviewed data on consecutive cases in which RAB was used to diagnose lung lesions from the very beginning of our experience with this technology (June 15th, 2018) until December 15th, 2018, at four centers in the US (University of Chicago Medical Center, Chicago, IL; University of Pittsburgh Medical Center Hamot, Erie, PA; Fox Chase Cancer Center, Philadelphia, PA; Spectrum Health, Grand Rapids, MI). The medical records of consecutive patients who were considered to require a guided bronchoscopy (EMN, VB with or without rEBUS) and underwent RAB to diagnose lung lesions, were reviewed and included in the analysis.
Inclusion and Exclusion Criteria
Consecutive patients evaluated for diagnosis of lung lesions considered to require guided bronchoscopy and underwent robotic bronchoscopy (must include 1, 2, and one of 3, 4, 5 or 6): 1. 18 years of age or older
- Acceptable candidate for an elective bronchoscopic procedure under general anesthesia
- Pulmonary lesions suspected of being primary lung cancers identified on thin-slice CT scan, requiring bronchoscopic biopsy for diagnosis based on the guidelines (10,11)
- Patients with a history of lung cancer presenting with new or growing lung lesions requiring tissue diagnosis for confirming recurrence or progression of disease
- Pulmonary lesions requiring tissue diagnosis in patients with a history of extrathoracic malignancy
- Patients with lung lesions suspected of being due to mycobacterial or fungal infection for which a tissue diagnosis was required prior to antimicrobial therapy
If inspection bronchoscopy demonstrated an endobronchial lesion that can be easily biopsied using a conventional white light bronchoscope.
Device or procedure-related complications: pneumothorax (any size, even if asymptomatic), significant airway bleeding (when the robotic bronchoscope was withdrawn and a flexible bronchoscope was used for cold saline, epinephrine or endobronchial blockers), respiratory failure within 24 hours of procedure (defined as new or increased requirement of supplemental oxygen or need for post-procedure ventilatory support, invasive or non-invasive)
Successful navigation: evidenced by obtaining an eccentric or concentric r-EBUS view, or diagnostic tissue on final pathology
Diagnostic yield: Defined as the percentage of procedures yielding a diagnosis based on final pathology ((True positives + True Negative)/ All biopsies performed). A true positive case is defined as a malignant histological diagnosis, or a benign diagnosis consistent with the patient’s clinical presentation, and required no further work-up. E.g. If biopsy showed organizing pneumonia in patient whose clinical presentation and course was consistent with the same, it was considered as a true positive. A true negative case consists of a benign diagnosis that required a subsequent biopsy (transthoracic or surgical biopsy) or follow-up imaging to confirm the diagnosis or show resolution or decrease in size. E.g. If the biopsy showed necrotizing granulomatous inflammation, and a subsequent biopsy or follow-up did not yield another specific diagnosis, it was considered as a true negative, consistent with prior ENB studies. However, if follow-up diagnostics were required and revealed a malignant etiology, or lesion growth, new lymphadenopathy or metastatic spread, it was considered as a false negative. (12) Additionally, if the patient received treatment for lung cancer without a confirmed diagnosis or received a new diagnoses of lung cancer from any site (including from non-index lesions, or from lymph nodes by EBUS, during or after the index procedure), the procedure was considered as non-diagnostic (false negative). Diagnostic yield based on lesion characteristics (size, centrality, density, location, bronchus sign, r-EBUS view obtained) are reported considering that cases with biopsy proven inflammation for which no follow-up was available, are false-negatives (conservative estimates).
Multi-center, retrospective, consecutive case series
The Monarch Endoscopy Platform is an FDA cleared medical device (510K #: 173760) intended to provide bronchoscopic visualization of and access to patient’s peripheral airways for diagnostic and potentially for therapeutic procedures. General anesthesia with an indwelling endotracheal tube was used for all procedures, with a tidal volume of 6–8 cc/kg and a positive end-expiratory pressure of 5–10 cm H2O. Airway inspection using a conventional white light bronchoscope was performed prior to RAB to rule out an obvious endobronchial lesion and to clear out sections from the airways. When mediastinal staging was indicated, EBUS-guided transbronchial needle aspiration (TBNA) was performed prior to RAB.
During RAB navigation, the physician uses a controller to move the robotic arms that contain rotatory pulleys to drive the bronchoscope. The bronchoscope is comprised of an outer sheath (6.0 mm) and inner scope (4.2 mm). Usually, once at a segmental bronchus, the sheath is locked in position and the scope is advanced into the smaller peripheral airways. The system uses an electromagnetic field generator and reference sensors much like other EMN bronchoscopy systems. r-EBUS was used as a confirmatory tool to verify proximity to the target. CBCT was not used in any of the cases. Biopsy tools are advanced through the working channel (2.1 mm), to biopsy the target lesion under fluoroscopy.
Mean and standard deviation are reported for continuous variables; categorical variables are reported as percentage and counts. Associations between lesion characteristics and diagnostic yield were calculated using chi-squared tests. Multivariable logistic regression was performed to determine the odds ratio of diagnostic yield adjusted for the following characteristics: lesion location, centrality, density and size, bronchus sign and r-EBUS view. Two-tailed p-values of less than 0.05 were considered statistically significant for all comparisons, and analyses were performed using Stata version 14.1 (StataCorp, College Station, TX).