CHEST issues guidelines on EBUS-TBNA

In terms of diagnostic yield, there was insufficient evidence to recommend for or against using an artificial airway when inserting the EBUS bronchoscope, the authors said. Reported practice is scattered and is largely based on expert opinion, operator comfort, sedation type, and institutional standards.

The placement of the endotracheal tube may block the ultrasonographic view of the higher paratracheal lymph nodes (lymph node stations 1, 2R, 2L, and 3P) and should be avoided if one of these lymph nodes is the sampling target of the procedure, they advised.

If using a transoral artificial airway, a bite block should be considered to protect the bronchoscope from bite damage; this approach is recommended independent of the depth of sedation. A minimum size of 8.0 should be used if placing an endotracheal tube for EBUS-TBNA to accommodate the scope diameter and leave room for gas exchange.

In an Ungraded Consensus-Based Statement, the guideline authors said that ultrasonographic features, such as size, shape, border, heterogeneity, central hilar structure, and necrosis can be used to predict malignant and benign diagnoses, but tissue samples still should be obtained to confirm a diagnosis.

Nine studies provided analysis of the characteristics of lymph nodes that predict malignancy during EBUS; however, the ultrasonographic features assessed were not the same in each study or they had varying definitions of what constituted “abnormal.” As a result, the ultrasonographic predictors of malignancy in lymph nodes are not reliable enough to forgo biopsy to obtain a definitive tissue diagnosis. However, the ultrasound features can be useful to guide sampling from lymph nodes most likely to be malignant.

A round shape, distinct margins, heterogeneous echogenicity, and a central necrosis sign were independently predictive of malignancy in one multivariate analysis that included more than 1,000 lymph nodes in nearly 500 patients. Furthermore, when all four factors were absent, 96% of the lymph nodes were benign.

In three additional studies, size criteria had conflicting results; one found size was not a reliable indicator, two others found that larger lymph nodes are more likely to harbor metastases. These studies also confirmed that round-shaped lymph nodes were more likely malignant than were triangular or draping lymph nodes. The measures used to define size may have caused the inconsistencies.

In a study that examined vascular image patterns within lymph nodes as a way to predict malignancy, nodes were considered malignant if vessel involvement increased in the node to rich flow with more than four vessels (grades 2 and 3) with a sensitivity of 87.7% and a specificity of 69.6%, suggesting that increased vascularity assessed by using power/color Doppler mode ultrasound is useful in predicting malignancy.

Two studies have assessed ultrasound features of lymph nodes in patients with sarcoidosis. In the first, lymph nodes with homogeneous echogenicity and a germinal center were more likely to indicate sarcoidosis than lung cancer. In the second, coagulation necrosis and heterogeneous echogenicity within lymph nodes were more likely to be present in tuberculosis as opposed to sarcoidosis.

In another Ungraded Consensus-Based Statement, the guideline authors said tissue sampling may be performed either with or without suction. In cases in which EBUS-TBNA is being performed with suction and the samples obtained are bloody, operators should consider switching to the use of no suction at the same sampling site. If intranodal blood vessels are visualized on EBUS imaging with or without Doppler imaging, operators should also consider obtaining samples without suction.

Needle choice should be determined by the operator, and the use of either a 21- or 22-gauge needle are acceptable options based on five trials comparing needle sizes, the authors said in a Grade 1C recommendation. No data are available on the use of 25-gauge needles.

“Future studies should investigate if ... smaller or more flexible needles would improve sampling at station 4L (known for its slightly angulated location) or if smaller needles would result in less blood contamination when sampling more vascular nodes. Studies should also examine if a particular needle size should be used depending on how the specimens are being processed (histopathology vs. cytopathology) and if needle size can affect the diagnosis of diseases that are more difficult to diagnose by EBUS-TBNA, such as lymphoma,” the authors wrote.

In the absence of rapid on-site evaluation (ROSE), the authors advised a minimum of three separate needle passes per sampling site in patients suspected of having lung cancer. The recommendation is an Ungraded Consensus-Based Statement.

Just one study of 102 patients with potentially operable non–small cell lung cancer and mediastinal adenopathy has examined the number of needle passes per sampling site. The results indicated optimal diagnostic values are reached after three passes. Each pass typically includes 5-15 agitations of the needle within the target site.