398	A. A. Goizueta and G. A. Eapen

and better ways to approach peripheral lung lesions. The development of thin and ultrathin bronchoscopes has improved the ability to maneuver distally through the bronchial tree. Additionally, virtual bronchoscopy and electromagnetic navigation have given us a threedimensional road map to the target lesion with bronchoscopic tracking. The synergistic combination of these bronchoscopic modalities with RP-EBUS has shown to improve diagnostic outcomes for peripheral lung lesions. Asashina et al. combined virtual bronchoscopy with RP-EBUS and guide sheath to perform biopsies of small peripheral lung lesions in 29 patients. They reported a sensitivity of 92% for lesions between 20 and 30 mm in size but only 44% for lesions less than 20 mm [23]. Ishida and colleagues constructed a similar study of 199 patients with small peripherally located lung lesions who were randomized to either RP-EBUS with virtual bronchoscopy or RP-EBUS alone and reported a diagnostic yield of 80% and 67%, respectively [24]. Eberhardt et al. randomized 120 patients with peripherally located lung lesions to undergo biopsy using either electromagnetic navigational bronchoscopy (ENB), RP-EBUS, or a combination of both techniques. The reported diagnostic yield was 88% with combined ENB/ RP-EBUS, 69% with RP-EBUS, and 59% with ENB alone [25]. The current literature suggests that there is synergy when using multimodal approaches to biopsy peripherally located lung lesions.

As discussed, once CP-EBUS became the tool of choice for mediastinal staging and the balloon catheter for the RP-EBUS to evaluate airway walls was discontinued, the RP-EBUS had become primarily a tool used for peripheral lung nodule localization. In addition to peripheral lung lesion biopsies, it can be used during placement of fducial markers to guide stereotactic radiation [26]. In areas where the balloon catheter is available, it has been used to visualize airway walls in the setting of tumor infltration, lung transplantation, and asthma [27–29].

Convex Probe Ultrasound

Description oftheEquipment and Technique

Equipment

CP-EBUS, also known as linear EBUS, is a bronchoscope with the addition of an integrated curvilinear ultrasound transducer at the distal end. At the tip of the bronchoscope, you will fnd a 10 mm long curved linear array electronic transducer in front of a 30° oblique facing fber-optic lens with 80° angle view (Fig. 23.5). In order to obtain an ultrasound image, the transducer must be in contact with the airway wall. To assist in obtaining contact, a balloon attached to the tip of the bronchoscope can be in ated with saline. The bronchoscope has an additional angulation range of 160° ante exed and 90° retro exed to assist with maneuverability and wall contact. The outer diameter of the insertion tube is 6.3 mm and the distal end outer diameter is 6.9 mm with a working channel of 2.2 mm. The ultrasound frequency ranges from 7.5 to 12.5 MHz with a penetration depth of about 5 cm and has a scanning view of 70–90° with respect to the longitudinal axis of the bronchoscope. This provides a real-time high-­resolution ultrasound image of the surrounding tissue and enables direct visualization of the echogenic needle as it penetrates the target. The CP-EBUS scope also has the ability to perform a real-time Doppler examination prior to penetrating the tissue in order to avoid any unwanted puncture of nearby vessels (Fig. 23.6).

During CP-EBUS-TBNA, two monitors are required to visualize both the bronchoscopic image and the ultrasound image. The CP-EBUS is connected to a central ultrasound scanner where the images are processed (Fig. 23.2). Ultrasound scanners are commonly equipped with color Doppler and even power Doppler modes. The ultrasound scanner can also capture images and take two-dimensional size measurements.

While multiple needle gauges are available, 21-gauge and 22-gauge needles are most com-

23  Endobronchial Ultrasound	399

Fig. 23.5  On the left, illustration of the 35° oblique facing fber-optic lens with an 80° angle of view at the tip of the CP-EBUS. On the right, the image demonstrates the

oblique angle of view bronchoscopically (Reprinted with permission from Olympus)

Fig. 23.6  The use of color Doppler while performing CP-EBUS to assist in avoiding biopsy of nearby vessels

monly used to perform EBUS-TBNA and will ft through the 2.2 mm working channel of the bronchoscope. The needle has adjustable settings that act as safety mechanisms to prevent damage to the bronchoscope as well as harm to the patient. The needle will exit the bronchoscope at a 20° angle with respect to the longitudinal axis of the bronchoscope and will extend to a maximum of 40 mm (Fig. 23.7). As the needle is passed outside of the bronchoscope, it can be visualized by the optic and the ultrasound as it passes through the tissue.

Technique

CP-EBUS-TBNA can be performed under conscious sedation or general anesthesia as an outpatient procedure. Under conscious sedation, the bronchoscope is inserted orally due to inability to pass the large distal tip of the scope easily through the nose. Additionally, under conscious sedation the cough re ex is still active which is signifcantly reduced with general anesthesia. An endotracheal tube or laryngeal mask airway (LMA) is used with general anesthesia with both having their advantages and disadvantages [30].

The CP-EBUS is initially inserted orally or through a LMA passed the vocal cords unless an endotracheal tube was used. The bronchoscope is then advanced to the area of interest and the balloon is in ated with normal saline to obtain optimal wall contact. A technical aspect to be aware of is that due to the 30° oblique angle of the optic, to obtain an en face view or the airway, the bronchoscope must be slightly retro exed. This technique can decrease contact between the ultrasound transducer and the wall requiring adjustment to either bronchoscopic position or balloon in ation. Locating the target, whether it be a lymph node or a parenchymal lesion, is done by using both airway and ultrasound landmarks. The bronchoscopic image provides a general starting point to allow a more precise and detailed scan with the ultrasound image. Vascular landmarks are the key to identifying the

Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/

400	A. A. Goizueta and G. A. Eapen
Fig. 23.7  (a) Identifes	a
the adjustable sheath
and guard to prevent
unwanted damage to the
bronchoscope or harm to
the patient. (b) The
balloon attached to the
tip of the CP-EBUS	b
in ated with saline and
the needle advanced
outside of the
bronchoscope through
the working channel
(Reprinted with
permission from
Olympus)

specifc lymph node stations according to the International Lymph Node Map by the International Association for the Study of Lung Cancer (Table 23.1) [31]. The Doppler on the CP-EBUS can also help recognize the surrounding blood vessels to assist in determining the borders of the lymph node stations and prevent unwanted vessel punctures. Sonographic lymph node features associated with an increased risk of malignancy, which include size greater than 1 cm, heterogeneous echogenicity, sharp border, round or oval shape, and the presence coagulation necrosis, can help guide the decision to biopsy the lymph node [32].

After the lesion to be biopsied has been identifed, the point of entry is determined by using the bronchoscopic view to visualize landmarks on the airway wall. This may require relaxation of the exion on the bronchoscope. The TBNA needle is then passed through the working channel of the bronchoscope while in the neutral position and locked into place. The needle has a sheath adjuster knob so that the sheath can be placed just outside the bronchoscope tip, which can be visualized on the bronchoscopic image, to prevent damage to the scope. Bronchoscopic exion is then used to reinitiate contact with the airway

wall to visualize the target on ultrasound and the needle is advanced in real-time under ultrasound to the appropriate depth (Fig. 23.8). The needle also has an internal stylet that is agitated within the needle to clear out the internal lumen of any unwanted bronchial tissue or debris. The stylet is then removed, and a syringe is attached that provides negative pressure while within the target prior to any passes taking place. Negative pressure is not required and in instances of hypervascular lesions it is not recommended as it may cause bloody samples. The needle can then be moved back and forth with a smooth motion traversing from the most proximal to most distal portion of the target if possible. Important tips to improve the sample quality while taking passes through the target include assuring the ultrasound image is in the same axis as the needle to allow visualization of each pass and not coming out or passing through the lesion. Lastly, the needle is retracted back into the sheath and unattached from the bronchoscope. The processing of the specimen from the TBNA is also key to achieve optimal results. To prepare the specimen for processing, the inner stylet is usually placed back into the needle to push out the frst few drops of the specimen onto a glass slide for rapid onsite

23  Endobronchial Ultrasound			401
Table 23.1  Lymph node stations
Lymph node	Defnition	Bronchoscopic landmark	CP-EBUS landmark
Station	– Right interlobar lymph node that	– RLL superior segment	– Descending interlobar
11Ri	lies between the RML and RLL	laterally, RML medially,	artery anteriorly
	bronchi	proximal to the RLL medial
		basal bronchi
		– Transducer placed in the
		RLL bronchus and scan
		between 8 and 11 o’clock
Station	– Right interlobar lymph node that	– RUL and RC1 laterally	– Truncus anterior and
11Rs	lies between the RUL and RML	– Transducer placed in the RBI	descending interlobar
	bronchus	and scan between 1 and 4	anteriorly
		o’clock
Station	– Right hilar lymph node that lies	– Right tracheobronchial angle	– Azygos vein proximally
10R	along the RMS distal to the azygos	proximally and the RUL	and the right pulmonary
	and proximal to the RUL	bronchus distally	artery distally
		– Transducer placed in the
		RMS and scan between 11
		and 3 o’clock
Station 4R	– Right lower paratracheal lymph	– Main carina distal and	– Lower border of the
	node that lies along the right mid/	medial, RMS distal and	azygos veins distally,
	lower trachea proximal to the	lateral, mid to upper trachea	SVC anteriorly,
	azygos vein and distal to the	proximally	brachiocephalic vein
	brachiocephalic vein	– Transducer placed in the	anterior and proximally
		lower trachea and scan
		between 11 and 3 o’clock
Station 2R	– Right upper paratracheal lymph	– Upper trachea looking to the	– Proximal to the right
	node that lies along the right mid/	right lateral aspect	lateral aspect of the
	upper trachea proximal to the	– Transducer placed in the	brachiocephalic vein
	brachiocephalic vein	upper trachea and scan	anteriorly
		between 11 and 3 o’clock
Station 7	– Subcarinal lymph node that lies	– Main carina medially,	– Right pulmonary artery
	between the mainstem bronchi	proximal to the RML	anteriorly when in the
		bronchus	RMS and the main
		– Transducer can be placed in	pulmonary artery
		the RMS and scan between 9	anteriorly when in the
		and 12 o’clock or placed in	LMS
		the LMS and scan between
		12 and 3 o’clock
Station 2L	– Left upper paratracheal lymph	– Upper trachea looking to the	– Proximal to the superior
	node that lies along the left upper/	left lateral aspect	border of the aortic arch
	mid trachea proximal to the	– Transducer can be placed in	laterally
	superior border of the aortic arch	the upper trachea and scan
		between 8 and 11 o’clock
Station 4L	– Left lower paratracheal lymph	– Mid/lower trachea, main	– Proximal to the superior
	node that lies along the left mid/	carina medially, proximal to	border of the left main
	lower trachea proximal to the	the left secondary carina	pulmonary artery, distal
	LMS, proximal to the superior	– Transducer placed in the	to the superior border of
	border of the left main pulmonary	LMS and scan between 9 and	the aortic arch
	artery, and distal to the inferior	12 o’ clock or in the lower
	border of the aortic arch	trachea scan between 9 and
		11 o’ clock
			(continued)

Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/