Pulmonary Medicine

Interventional Bronchoscopy: Conventional Transbronchial Needle Aspiration (cTBNA)

General description of procedure, equipment, technique

Conventional Transbronchial Needle Aspiration (cTBNA)

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 transbronchial needle aspiration (cTBNA) without endobronchial ultrasound guidance.

Needle aspiration of mediastinal lymph nodes was originally described in 1949. Contrast-enhanced computed tomography is performed prior to the procedure, and knowledge of the anatomic relationship of the tracheobronchial tree to lymph nodes and blood vessels is essential. In order to obtain an adequate specimen, the needle that is passed through the flexible bronchoscope must reach the core of the lymph node while avoiding nearby vascular structures. TBNA of lymph nodes in the subcarinal and right paratracheal regions detects metastasis with a higher sensitivity than does TBNA of the left paratracheal lymph nodes.

An understanding the mediastinal anatomy is essential for safe performance of TBNA. To the right of the distal third of the trachea are the superior vena cava and azygos vein, and directly anterior to the trachea, above the level of the primary carina, lie the innominate artery and aortic arch. These major vessels cross the origin of the left main stem bronchus and lie anterior and to the left of the distal third of the trachea, making an easily recognizable pulsatile imprint.

The main pulmonary artery divides into the right and left branches within the concavity of the aortic arch. The left pulmonary artery runs antero-superiorly, in close approximation (within 3 to 5 mm) to the left mainstem bronchus; the right pulmonary artery lies anterior to the right mainstem bronchus and the origin of the upper lobe bronchus. The esophagus lies in close approximation (within 2 to 3 mm) of the posterior wall of the trachea and the left mainstem bronchus. Obviously, enlarged lymph nodes provide for better diagnostic yield.

A wide variety of biopsy needles are available. Retractable needles should be the only ones used, as needle-related damage to the bronchoscope's working channel is common and costly. The most commonly used needle is 22 gauge. While a larger 19-gauge needle is used for providing samples for histology, the performance of a larger needle has not been evaluated extensively, although some studies suggest the 19-gauge needle may have a higher diagnostic yield compared with the 22-gauge.

Indications and patient selection

Needle aspiration has been utilized in the diagnosis of endobronchial lesions, peripheral lung nodules, and mediastinal abnormalities (e.g., lymphadenopathy). The most common applications of TBNA are the diagnosis and staging of lung cancer.

Contraindications

There are no absolute contraindications to cTBNA other than those for bronchoscopy including irreversible coagulopathy and cardiopulmonary instability.

Details of how the procedure is performed

During insertion of the needle-containing catheter, the flexible bronchoscope is kept as straight as possible, with its distal tip in the neutral position, in order to prevent damage to the working channel, and the needle tip is retracted within the device's metal hub during its passage through the working channel. Then the catheter is retracted, and the tip of the needle is kept in view distal to the tip of the bronchoscope.

There are at least three described methods for needle insertion including the piggyback, jab, and cough. The bronchoscope is advanced as a single unit to the target area, and the tip of the needle is anchored in the inter-cartilaginous space prior to the needle's penetration of the airway wall. The needle is then inserted, with its metal hub against the tracheobronchial wall by advancing the bronchoscope and needle en bloc, jabbing the needle forward, or by having the patient cough. Once the needle inserted, suction is applied at the proximal side port of the bronchoscope using a 60-ml syringe. The catheter is then agitated to and fro to obtain cytologic specimens during continuously applied suction. After suction is released, the needle is withdrawn from the target site.

The specimen for cytology is prepared using air from a 60-ml empty syringe to spray the specimen onto the slide, smearing it using another slide, and immediately placing it in a 95 percent alcohol solution. If a rapid, on-site evaluation (ROSE) service is available, real-time feedback from the cytologist helps to reduce the number of punctures required. Having a cytopathologist on-site to check for sample adequacy has been demonstrated to increase diagnostic yield. A trained assistant is also essential for procedure success and proper tissue handling.

Interpretation of results

TBNA establishes the diagnosis and provides staging information in a single procedure. A positive N2 or N3 lymph node for non-small-cell lung cancer directs a nonsurgical approach to management. Positron emission tomography (PET) may be helpful in defining which lymph nodes should be sampled. The diagnostic yield of conventional TBNA has been reported to be 78% with appropriate case selection for lung cancer.

The utility of TBNA in the evaluation of lymphoma has been limited since the diagnosis usually requires larger samples of nodal tissue than TBNA can provide with a reported diagnostic yield of 36%. However, the diagnosis of lymphoma may be established using a combination of cytology and flow cytometry. Several reports have confirmed an increase in the diagnostic yield when both transbronchial lung biopsies and TBNA are performed in patients with suspected sarcoidosis with a diagnostic yield of 48% for cTBNA which increases to 85% with the addition of transbronchial and endobronchial biopsies. The addition of EBUS-guided sampling further increases the diagnostic yield to 93%.

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

See section on interpretation of results.

Outcomes (applies only to therapeutic procedures)

Not applicable.

Alternative and/or additional procedures to consider

Transbronchial needle aspiration with image guidance, endobronchial ultrasound-guided TBNA (EBUS TBNA) has a much higher diagnostic yield and increased safety due to its ability to identify the lymph nodes and adjacent vascular structures. This does come at an increase in equipment cost for the bronchoscopes as well as for the processor.

Complications and their management

Complications following TBNA are uncommon if appropriate precautions are taken and proper technique is employed. The most common complication is damage to the working channel of the bronchoscope. Infrequent complications include pneumothorax, pneumomediastinum, and hemomediastinum.

No firm recommendations have been provided regarding antibiotic prophylaxis. Oozing of a minimal amount of blood from the puncture site may be encountered.

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