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Abe et al. Mini-invasive Surg 2023;7:28 https://dx.doi.org/10.20517/2574-1225.2023.15 Page 3 of 14

axillary line of the 3rd and 8th ICSs; and a 5-mm port was inserted in the 6th ICS slightly midline of the
subscapular angle [Figure 1A]. The energy devices used are mainly electrocautery or vessel sealing systems.

RAMIE was performed using a robotic system (da Vinci Xi System; Intuitive Surgical Inc., Sunnyvale, CA,
USA). The da Vinci Xi System ports for arms 1, 2, 3, and 4 were used for the 9th ICS at the subscapularis
line, the 7th ICS behind the axillary line, the 5th ICS behind the axillary line, and the 3rd ICS at the mid-
axillary line, respectively. In addition, an assistant port was placed at the 6th ICS slightly anterior to the
mid-axillary line. Because an artificial pneumothorax with an 8-mmHg carbon dioxide gas was used with
the Airseal® Intelligent Flow System, we used an Airseal® 5-mm port on the dorsal aspect of the 8th ICS
[Figure 1B]. During RAMIE, we primarily used a 30 -angle thoracoscope. The primary instruments used by
o
the surgeon during RAMIE were sharp monopolar cutting scissors, which were used to dissect, coagulate,
and cut tissue during the procedure.

The surgical procedures for MIE and RAMIE were similar, although the port placement and the surgical
devices used were different [Supplementary Video 1A and B].

Surgical procedure
Middle and lower mediastinal dissection
The right pulmonary ligament was dissected, the pericardial surface was exposed, the pericardial side of the
tracheal bifurcation lymph node was dissected, and the membranous part of the left main bronchus was
identified. The lower pulmonary branch of the right vagal nerve was sacrificed; only the right upper
pulmonary branch was preserved. During dissection of the tracheal bifurcation, it is important to be aware
of the tracheal sheath [Figure 2A]. The azygos arch was also divided using a linear stapler. Next, a
descending peri-aortic dissection was performed. At this time, we were aware of the ligament interpleural de
[8]
Morosow [Figure 2B]. Patients with cT3 or more disease in our department were treated with combined
resection of the thoracic duct, while patients with cT1-2 disease were treated with preservation of the
thoracic duct. In cases involving thoracic duct preservation, the ligament interpleural de Morosow was
preserved, but in cases involving combined resection of thoracic ducts, the ligament interpleural de
Morosow was incised, and the thoracic duct and surrounding lymph nodes were excised [Figure 2B].

Dissection of the right laryngeal nerve lymph nodes
It is important to be aware of the tracheoesophageal sheath and right tracheoesophageal artery (TEA)
[9]
during right recurrent laryngeal nerve (RLN) lymph node dissection . The mediastinal pleura was incised
up to the right subclavian artery (SCA) while preserving the epineurium of the right vagal nerve. The level
of the vagal nerve epineurium, the tracheoesophageal sheath, and the right RLN were identified at the
recurrent part [Figure 2C]. The upper thoracic esophagus was mobilized from the trachea and vertebral
side, and the dissected right RLN lymph nodes were detached from the tracheal sheath at the right wall of
the trachea. Next, three to five esophageal branches of the right RLN were dissected, and then the right RLN
was dropped ventrally, continuing the dissection of the tissue to the pre-tracheal region as far ventrally as
possible [Figure 2D]. The right RLN lymph nodes were dissected as far as possible into the neck. In some
cases, it was possible to identify the pulsation of the right inferior thyroid artery and the lower pole of the
thyroid gland [Figure 2E].

Dissection of the left RLN nodes
It is also important to be aware of the microanatomy of the tracheoesophageal sheath and left TEA, as well
as the left RLN lymph node dissection [Figure 2F]. After taping the upper thoracic esophagus, the trachea
[9]
was expanded ventrally. From the left aspect of the trachea, the dissected tissues of the left RLN lymph