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Page 6 of 10 Liu et al. Mini-invasive Surg 2020;4:44 I http://dx.doi.org/10.20517/2574-1225.2020.20

Table 4. Transthoracic vs. transhiatal route in RAMIE
RAMIE Merits Limitations
Transthoracic Wide operative field. Thoracic wall and pleura destruction are unavoidable.
Superior mediastinum lymph node dissection can be Differential lung ventilation is still needed in most case
performed in the same operative field
Transhiatal No need for thoracic wall destruction. Narrow operative field.
No pleurotomy. Need a decent experience for mediastinum lymph node
No need of differential lung ventilation. dissection under mediastinoscopy
No need for a change in body position.
Almost no postoperative respiratory complications
RAMIE: robot-assisted minimally invasive esophagectomy

[53]
invasive operative method but oncologically inferior to radical esophagectomy . Although lymph node
dissection of the lower mediastinal field is considered to be equivalent to radical esophagectomy, when
it comes to the middle mediastinal field, it shows shortages because conventional endoscopic devices
suffer from the paralleled right- and left-hand in the deep narrow operative fields. Meanwhile, the robot
has articulated instruments and enhanced three-dimensional magnified view, which can move freely in
the deep narrow cavity. It has been proven that RAMIE can overcome the limitations of the conventional
transhiatal MIE and can dissect lymph nodes equivalent to radical esophagectomy . Yoshimura et al.
[55]
[54]
showed that transhiatal RAMIE is associated with fewer pulmonary complications (0%) and better
postoperative quality of life. However, it requires two LND steps. Posterior and middle mediastinal LND
is performed using transhiatal RAMIE, followed by cervical mediastinoscopy for superior mediastinal
LND. Mori et al. showed that the radicality of transmediastinal esophagectomy is equivalent to that
[56]
of transthoracic esophagectomy in terms of the number of harvested lymph nodes and the pathology of
surgical margins. Similarly, postoperative pneumonia did not occur in the transhiatal group. Although
short-term and long-term outcomes were reported to not be inferior, due to the narrow operative field
with the transhiatal procedure and mediastinoscopy, transhiatal RAMIE appears to be a more complex
procedure. RAMIE operative routes are summarized in Table 4.

OPERATIVE POSITIONS IN RAMIE
Acute lung injury occurs in 25%-30% of patients after transthoracic esophagectomy, and single lung
ventilation has been implicated in its pathogenesis . Until recently, RAMIE has been performed with the
[57]
patient in the left lateral decubitus position in a setting of single-lung ventilation. Full lateral decubitus
[58]
position with a cephalic parallel approach was reported to save some operative time (381 ± 57.7 min) .
However, this approach requires total lung collapse and is therefore, often accompanied by serious
[59]
pulmonary complications. To overcome the disadvantages of differential ventilation, Palanivelu et al.
performed MIE with patents in a prone position. With their large patient cohort, they found that the
prone position takes advantage of gravity to displace the lung from the dorsal thoracic structures and the
esophagus, and that it has lower respiratory complications and shorter operative times due to the excellent
exposure of the operative field and the better ergonomics for the surgeon. Sometimes, the vertebral column
[60]
may obstruct the view of the operative field. Ruurda et al. reviewed the application of the prone position
in RAMIE, with the patient cart of the robot system standing on the patient’s side and extending its arms in
a direction crossing the longitudinal axis of the patient. In the subsequent abdominal phase, the patient cart
[58]
must be repositioned in front of the patient’s head. This patient cart repositioning is time-consuming .
On the other hand, urgent conversion to a classic thoracotomy, if needed, is probably more difficult with
the prone position . As a solution to overcome this problem, whilst retaining the benefits of the prone
[61]
position, a relatively complicated position, a modified semi-prone position has been adopted by surgeons
[62]
around the world . Operative positions are summarized in Table 5.