Discussion
In the present review, we summarize the safety and diagnostic utility of
the minimally invasive endosonographic modalities, EBUS-TBNA and
EUS-B-FNA in children. We found that EBUS-TBNA and EUS-B-FNA have an
excellent safety profile as the major complication rate is minimal. The
overall diagnostic yield (61%) is similar to the diagnostic yield of
EBUS-TBNA in adults in real-world settings.(21) The excellent sampling
adequacy has important clinical relevance. The findings highlight that
when used as first-line investigations for evaluation of mediastinal
lymphadenopathy in children, invasive surgical procedures may be
avoidable in a majority of them.
Wurzel et al. reported the first case of EBUS TBNA in children using an
adult EBUS-TBNA bronchoscope (2009), for the diagnosis of Sarcoidosis.
(7) After this, few studies and case reports have highlighted the use of
broncho-endosonographic modalities in children and interest in this
field has grown. There are particular concerns regarding the use of
EBUS-TBNA and EUS-B-FNA in children. The available EBUS bronchoscopes
have an outer diameter of 6.9 – 7.4 mm. Recently, a thinner EBUS
bronchoscope has become available (6.3 mm diameter). The diameter of all
the available EBUS scopes is larger than that of the conventionally used
flexible bronchoscopes in children (usually 2.8-4.2 mm). Therefore, the
performance of EBUS-TBNA is challenging in younger children with a
smaller trachea.(16) Introduction of the EBUS bronchoscope through the
oesophagus to perform mediastinal lymph node aspiration, a technique
described as transesophageal bronchoscopic ultrasound-guided fine-needle
aspiration (EUS-B-FNA) approach has been one of the most significant
additions for pediatric mediastinal lymphadenopathy. (6) The first
description of this modality in children was to sample the subcarinal
lymph node in a 3-year-old child. (16) EUS-B-FNA allows successful
sampling from oesophagal accessible lymph node stations (like
subcarinal, lower left paratracheal and para-oesophagal) in children as
young as one year.(17) This approach has the advantage of being
complementary to the traditional EBUS and can be the sole approach in
small children. Avoidance of tracheal entry during EUS-B-FNA minimizes
the risk of impairment of ventilation and desaturation. The available
literature suggests that traditional adult EBUS scopes can be easily
used through the tracheal route in children more than 12 years of age or
weighing more than 50kg.
Sedation and anaesthesia constitute an essential aspect of optimization
of procedure comfort. In adults, EBUS-TBNA is routinely performed under
moderate sedation, although deep sedation/GA is optional. In children,
ensuring adequate anaesthesia is vital for safety and procedural
success. As the scope for error during needle manipulation during
sampling is minimal, a comfortably sedated child with proper ongoing
ventilation is ideal. The sedation practices reported in the studies on
EBUS in children are varied. While many operators have used general
anaesthesia, studies have shown that the procedure can be very well be
performed using moderate to deep sedation without an artificial
airway.(13) While using general anaesthesia, either an LMA (laryngeal
mask airway) or an endotracheal tube may be used. The diameter of the
EBUS scope varies from 6.3–7.4 mm, hence the minimum size of
endotracheal tube required for easy passage of the scope would be around
8 mm. This could be problematic in small children. Also, the use of an
endotracheal tube may cause difficulty in accessing the upper and lower
paratracheal lymph nodes.(14) An appropriately sized supraglottic airway
(Laryngeal Mask Airway) can help circumvent this problem. The minimum
size of the LMA recommended is 2.0 (IGel LMA). While using an artificial
airway, the scope may be required to be removed intermittently to enable
ventilation. While using general anaesthesia, inhalational sevoflurane
and neuromuscular blockade using intravenous atracurium can be used.
(18) Administration of anaesthesia and monitoring by a trained
anesthesiologist is ideal.
Various gauge EBUS-TBNA needles are available like 21G, 22G, 19G and
25G. Most of the published literature in children describes the use of
either a 21G or a 22G needle. The reported yield of either of the two
needles in adults is similar. 19 G needles may allow one to obtain
larger specimens. However, currently, no data is available with the use
of 19G and 25G EBUS-TBNA needles in children. We believe that Rapid
on-site evaluation (ROSE) by a pathologist is ideal during
EBUS-TBNA/EUS-B-FNA in children as it may allow minimization of needle
punctures and reduce the total duration of procedure thereby minimizing
the duration and risks of anaesthesia.
EBUS was developed in adults mainly for staging and diagnosis of lung
cancer. However, since then, the diagnostic utility of EBUS is
established in many other benign diseases like Sarcoidosis. In children,
tuberculosis and lymphoma constituted the two most common pre-clinical
diagnosis. EBUS-TBNA has excellent diagnostic performance for
Tuberculous mediastinal lymphadenopathy. (22) EBUS-TBNA can be a useful
initial minimally invasive diagnostic modality in lymphoma if it is
combined with immunophenotyping and molecular analysis. (23)
The pooled diagnostic yield of EBUS-TBNA in the meta-analysis was 61%
which approximates the diagnostic yield of EBUS-TBNA in adults (around
63%) in real-world settings. (21) The excellent sampling adequacy
(98%) signifies that representative lymph nodal tissue is nearly always
obtained. The data for determination of sensitivity, specificity,
positive and negative predictive values and diagnostic accuracy were not
provided in any study due to lack of a detailed follow-up. Gilbert et
al. reported that EBUS TBNA helped in avoiding invasive surgical biopsy
in 62% of cases. (15) In addition to the risk of complications,
invasive procedures entail more cost.
Overall endosonographic procedures (EBUS-TBNA/EUS-B-FNA) have an
excellent safety profile and favourable cost-benefit. The complication
rate is low, approximately 0.05%. (24) Although EUS-B-FNA is
complimentary to EBUS TBNA, it has a small risk of oesophagal
perforation (0.02%) which may occur due to puncture of the node as the
needle traverses the oesophagal wall. (25) Ideally, these procedures in
children should be performed by experienced bronchoscopists who are
regularly performing these procedures in adults. Paediatric
bronchoscopists can quickly gain skills in this modality with training.