Pulmonary Medicine

Interventional Bronchoscopy: Endobronchial Ultrasound

General description of procedure, equipment, technique

Endobronchial Ultrasound

Initially defined in 1995 and subsequently described in European Respiratory Society (ERS) and American Thoracic Society (ATS) guidelines, interventional pulmonology is "the art and science of medicine as related to the performance of diagnostic and invasive therapeutic procedures that require additional training and expertise beyond that required in a standard pulmonary medicine training program." Clinical entities encompassed within the discipline include complex airway management, benign and malignant central airway obstruction, pleural diseases, and pulmonary vascular procedures.

Diagnostic and therapeutic procedures pertaining to these areas include rigid bronchoscopy, transbronchial needle aspiration, autofluorescence bronchoscopy, endobronchial ultrasound, transthoracic needle aspiration and biopsy, laser bronchoscopy, endobronchial electrosurgery, argon-plasma coagulation, cryotherapy, airway stent insertion, balloon bronchoplasty and dilatation techniques, endobronchial radiation (brachytherapy), photodynamic therapy, percutaneous dilatational tracheotomy, transtracheal oxygen catheter insertion, medical thoracoscopy, and image-guided thoracic interventions. This presentation focuses on endobronchial ultrasound.

Endobronchial ultrasound (EBUS) is a bronchoscopic technique that uses ultrasound to visualize structures of the mediastinal adjacent to the airway wall to enable performance of TBNA. EBUS may be used to guide bronchoscopic sampling of mediastinal lymph nodes, hilar lymph nodes, or peripheral pulmonary nodules. EBUS is different from endoscopic ultrasound (EUS); while both techniques permit imaging and guided sampling of mediastinal lymph nodes, EBUS is performed during bronchoscopy, while EUS is performed during upper endoscopy.

Indications and patient selection

EBUS is used to guide bronchoscopic sampling of mediastinal lymph nodes, hilar lymph nodes, and peripheral pulmonary nodules.

Contraindications

A contraindication is when no lymph node is visualized.

Details of how the procedure is performed

Radial Probe EBUS (RP-EBUS) provides 360-degree images of the airway wall and surrounding structures and visualization of the layers of the airway wall. RP-EBUS is performed by placing the bronchoscope tip in the area of interest, inserting the radial ultrasound probe through the working channel, and inflating its balloon sheath with water. 20 MHz or 30 MHz miniature radial probes provide a depth of penetration of 5 mm. An ultra-miniature radial probe may be extended into subsegmental bronchi, allowing visualization of peripheral intrapulmonary nodules.

Convex Probe EBUS (CP-EBUS) provides a view that is parallel to the shaft of the bronchoscope. Color flow and Doppler features permit identification of vascular and cystic structures, thus enabling real-time TBNA. The procedure is performed using a 7.5 MHz convex ultrasound probe attached to the bronchoscope's tip. The ultrasound image and conventional bronchoscopy image may be displayed on the same monitor, and EBUS-guided TBNA of mediastinal and hilar lymph nodes may be performed real-time.

A transbronchial needle system contains a 22-gauge, retractable, sharp, beveled needle with an internal sheath that is inserted through the working channel, just proximal to the ultrasound probe. Once the catheter emerges from the bronchoscope, the needle is advanced from the catheter, locked into position, and then pushed through the bronchial wall into the target lymph node under direct ultrasound visualization. Suction is applied from a syringe, and the catheter slowly agitated. When suction is released, the needle is pulled into the flexible catheter.

To biopsy peripheral lung nodules, a ultra-miniature radial probe is placed in a guide sheath, and the probe and guide sheath are advanced through the working channel of the bronchoscope until the nodule is visible. The radial probe is removed, leaving the guide sheath in position. A biopsy forceps or bronchial brush is then inserted through the guide sheath and the nodule sampled.

Interpretation of results

EBUS is useful in staging the nodal component in lung cancer. Once enlarged mediastinal lymph nodes are identified by CT scan or are identified as metabolically active on PET, lymph node sampling facilitates evaluation since the sensitivity and specificity of imaging alone in the detection of lymph node metastasis are inadequate and similar to TBNA.

A clinical trial of RP-EBUS in patients with suspected lung cancer demonstrated that RP-EBUS-guided TBNA was more sensitive than TBNA alone (84% versus 58%, respectively); no difference was found between the two procedures with regard to subcarinal lymph node sampling.

Another study demonstrated the proof-of-principle that CP-EBUS-guided TBNA successfully samples mediastinal or hilar lymph nodes in patients with known or suspected non-small cell lung cancer (NSCLC). Malignancy was detected with a sensitivity of 95 percent, a specificity of 100 percent, and diagnostic accuracy of 96 percent. A large meta-analysis of eleven studies showed similar sensitivity and specificity for the technique.

A combination of EBUS-guided TBNA and EUS-FNA may make the entire mediastinum accessible to node sampling, thereby decreasing the need for more invasive procedures. The combination appears to improve the diagnostic yield when compared to either procedure alone.

RP-EBUS-guided TBNA is useful in performing biopsies of peripheral pulmonary nodules. In a large, randomized trial in which patients were assigned to RP-EBUS-guided or conventional transbronchial biopsy, evaluation of nodules that were smaller than 3 cm demonstrated that RP-EBUS-guided transbronchial biopsy identified malignant disease with a sensitivity of 75 percent and accuracy of 83 percent, while conventional transbronchial biopsy identified malignant disease with a sensitivity 31 percent and an accuracy of 50 percent. However, the diagnostic yield with RP-EBUS-guided TBNA is lower than that of CT-guided percutaneous transthoracic needle aspiration for larger lesions. Therefore, RP-EBUS TBNA provides an advantage only if the lesion is smaller than 3 cm.

CP-EBUS-TBNA allows real-time sampling of mediastinal lesions, as does TBNA. In a randomized study of sarcoidosis, CP-EBUS-TBNA was shown to have a higher diagnostic yield (sensitivity of 83%, specificity of 83%) than conventional TBNA (sensitivity of 61%, specificity of 100%). Similarly, EBUS is an effective diagnostic method in the diagnosis of lymphoma.

EBUS does have some disadvantages that standard fiberoptic bronchoscopy does not have. The bronchoscope used is larger than a conventional one, it provides poorer image quality, and its use requires some additional practice. Because of its poorer quality image, the EBUS bronchoscope should not be used for initial airway inspection. Finally, no needle is currently available for use with the bronchoscope to provide histology, as the needle size is the same 22-guage device that is used with TBNA.

Performance characteristics of the procedure (applies only to diagnostic procedures)

Not applicable

Outcomes (applies only to therapeutic procedures)

Not applicable

Alternative and/or additional procedures to consider

Alternative procedures to consider are surgical options like mediastienscpy or video-assisted thoracic surgery.

Complications and their management

The addition of EBUS in performing TBNA does not add to the complication rate, which is similar to that seen with conventional TBNA.

What’s the evidence?

Chao, TY, Chien, MT, Lie, CH. "Endobronchial ultrasonography-guided transbronchial needle aspiration increases the diagnostic yield of peripheral pulmonary lesions: a randomized trial". Chest. vol. 136. 2009. pp. 229.

A report describing the use of ultrasound in increasing the diagnostic yield of bronchoscopy in the evaluation of peripheral lung lesions.

Eberhardt, R, Anantham, D, Ernst, A, Feller-Kopman, D, Herth, F. "Multimodality bronchoscopic diagnosis of peripheral lung lesions: a randomized controlled trial.". Am J Respir Crit Care Med. vol. 176. 2007. pp. 36-41.

A report on the use of multiple techniques to maximize diagnostic yield. Unfortunately, most institutions do not have all of the technology described.

Gu, P, Zhao, YZ, Jiang, LY. "Endobronchial ultrasound-guided transbronchial needle aspiration for staging of lung cancer: a systematic review and meta-analysis". Eur J Cancer. vol. 45. 2009. pp. 1389.

An elegant systematic review of EBUS.

Herth, FJ, Becker, HD, Ernst, A. "Conventional vs endobronchial ultrasound-guided transbronchial needle aspiration: a randomized trial". Chest. vol. 125. 2004. pp. 322.

An early paper showing the use of ultrasound (albeit not in real time) in conjunction with TBNA.

Hurter, T, Hanrath, P. "Endobronchial sonography: feasibility and preliminary results". Thorax. vol. 47. 1992. pp. 565.

One of the earliest publications on the use of endobronchial ultrasound.

Hwangbo, B, Kim, SK, Lee, HS. "Application of endobronchial ultrasound-guided transbronchial needle aspiration following integrated PET/CT in mediastinal staging of potentially operable non-small cell lung cancer". Chest. vol. 135. 2009. pp. 1280.

A study that confirms the value of EBUS in the diagnosis of lung cancer.

Kennedy, MP, Jimenez, CA, Bruzzi, JF. "Endobronchial ultrasound-guided transbronchial needle aspiration in the diagnosis of lymphoma". Thorax. vol. 63. 2008. pp. 360.

A study that demonstrates the value of ultrasound in the diagnosis of lymphoma.

Tremblay, A, Stather, DR, Maceachern, P. "A randomized controlled trial of standard vs endobronchial ultrasonography-guided transbronchial needle aspiration in patients with suspected sarcoidosis". Chest. vol. 136. 2009. pp. 340.

An elegant study that shows the use of ultrasound in the diagnosis of sarcoidosis.

Yasufuku, K, Chiyo, M, Koh, E. "Endobronchial ultrasound guided transbronchial needle aspiration for staging of lung cancer". Lung Cancer. vol. 50. 2005. pp. 347.

One of the best available studies showing the use of ultrasound in lung cancer staging.
You must be a registered member of Renal and Urology News to post a comment.

Sign Up for Free e-newsletters