**7. Prone position versus lateral decubitus position for thoracic step**

To minimize morbidity and mortality after an esophagectomy, a thoracoscopic approach was introduced as a minimally invasive option [58, 59]. This procedure is most commonly performed with the patient in the left lateral decubitus position, but prone position is a valid alternative. Cuschieri et al. [60] first explained the prone position (PP) for thoracoscopic esophageal mobilization in 1994. They described this technique in 6 patients and compared the results with those of left lateral position in 20 patients. They suggested that PP had technical advantages and reduced postoperative complications. However, this technique was not widely used at that time, and more than 10 years have passed by to find publications that talk about PP again. In 2006, Palanivelu et al. [10] reported their experience with 130 patients treated by thoracoscopic esophagectomy in PP raising new interest in this procedure. Many reports about that have been published so far.

The primary benefit of the PP is derived from the anatomical exposure: the lung falls away as a consequence of gravity and the esophagus is better visualized. This permits performance of the operation without the need for collapsing the right lung using a double-lumen endotracheal tube. If we use a single-lumen endotracheal tube, the partial or intermittent ventilation of the right lung reduces the venous shunt effect and results in opening up a great percentage of the alveoli helping in prevention atelectasis. Moreover, this type of ventilation does not make difficult the surgical procedure or prolong its duration. In a prone position, we have better functional residual capacity than in a supine position. Furthermore, ventilation perfusion ratio is well maintained, and hypoxia and hypercarbia are avoided. All of this, aided by gravity, reduces lung injury. All that was mentioned previously could explain why Cuschieri et al. [60] described a decrease in respiratory complications in PP. Luketich group [9] performed the thoracoscopic surgery in LDP and reported the incidence of pneumonia in 7.6% and adult respiratory distress syndrome (ARDS) in 5% of the patients. Palanivelu et al. [10] talks about pneumonia in 1.54% of the patients and ARDS in 0.77% with PP approach.

As we have described already, gravity and artificial pneumothorax may improve mediastinal organs and structures exposure without any help of an assistant: this is another benefit of the PP. It makes possible the use of only three trocars, while four of them are needed in lateral decubitus approach. Prone position also promotes blood and other fluids from accumulating in the right anterior thorax, instead of posterior mediastinum that takes part of operative field. Thus, intermittent suction of accumulated fluids is not required during surgery. In the lateral position, the esophagus is in a dependent place and any pooling of blood obscures the surgical field.

Recently, Javed et al. [61] have published a comparative study between MIE in prone versus lateral decubitus position (LDP). They described the surgery in LDP using an additional trocar (four in total) for the assistant to retract the lung and to suction out the blood, whereas they only need three for PP technique. In this study, authors report low blood loss intraoperative, which was significantly less in PP group. Kubo et al. [62] also describe significantly lower blood loss with this approach. This fact could be explained due to a better exposure in PP that allows a more meticulous dissection avoiding damage to vessels and other thoracic structures and decreasing bleeding.

Noshiro et al. [63] have published a study to describe whether lymphadenectomy along the left recurrent laryngeal nerve is facilitated in the PP. Lymph nodes along this nerve are frequently involved by carcinoma cells, and their complete dissection is required [58]. They conclude that when PP is compared with LDP, lower blood loss and better exposure of the surgical field around the left recurrent laryngeal nerve occurs in first group. Although they describe slightly higher number of the resected lymph nodes in the PP, they do not find significant differences. On the other hand, Javed et al. [61] show a significantly higher lymph node yield in PP and the number of patients with affected lymph nodes is also significantly higher.

Most of the reports [10, 61] describe a shorter operative time for a thoracoscopic esophagectomy in PP than in LDP. As we have said before, the best exposure of the surgical field allows for faster and better quality surgery.

Fabian et al. [64] suggested that the learning curve for the prone position approach appears to be relatively short, within the first five cases. This author also says that prone approach may result in better dissection into the neck explained by pneumatic dissection from the thoracic cavity cranially along the esophagus. This maneuver simplifies the neck surgery that could lead to less morbidity in cervical step.

The incidence of complications, such as anastomosis leak, gastric tip necrosis, chylothorax, tracheal, or vocal cord injury is comparable between PP and LDP according to many reports. Other clinical outcomes seem to be similar between both: median length of stay, discharged within 10 days, and in-hospital mortality [63, 64]. As we have commented at the beginning, it might be possible to reduce respiratory morbidity using PP approach.

In addition, in PP the surgeon's wrist and shoulder joins are in a neutral position in relation to the forearms and upper arms, minimizing fatigue and maximizing ergonomic function. The view of the monitor stands parallel to operative field and ergonomic position of the surgeon makes easier hand-eye coordination. In contrast in LDP, the surgeon's view of the monitor must be turned upside down to avoid the counterimage when two monitors are set on each side. In this situation, hand-eye coordination cannot be obtained smoothly if a scope-holding assistant does not work correctly.

As we have described already, gravity and artificial pneumothorax may improve mediastinal organs and structures exposure without any help of an assistant: this is another benefit of the PP. It makes possible the use of only three trocars, while four of them are needed in lateral decubitus approach. Prone position also promotes blood and other fluids from accumulating in the right anterior thorax, instead of posterior mediastinum that takes part of operative field. Thus, intermittent suction of accumulated fluids is not required during surgery. In the lateral position, the esophagus is in a dependent place and any pooling of blood obscures the

Recently, Javed et al. [61] have published a comparative study between MIE in prone versus lateral decubitus position (LDP). They described the surgery in LDP using an additional trocar (four in total) for the assistant to retract the lung and to suction out the blood, whereas they only need three for PP technique. In this study, authors report low blood loss intraoperative, which was significantly less in PP group. Kubo et al. [62] also describe significantly lower blood loss with this approach. This fact could be explained due to a better exposure in PP that allows a more meticulous dissection avoiding damage to vessels and other thoracic structures

Noshiro et al. [63] have published a study to describe whether lymphadenectomy along the left recurrent laryngeal nerve is facilitated in the PP. Lymph nodes along this nerve are frequently involved by carcinoma cells, and their complete dissection is required [58]. They conclude that when PP is compared with LDP, lower blood loss and better exposure of the surgical field around the left recurrent laryngeal nerve occurs in first group. Although they describe slightly higher number of the resected lymph nodes in the PP, they do not find significant differences. On the other hand, Javed et al. [61] show a significantly higher lymph node yield in PP and the number of patients with affected lymph nodes is also significantly higher. Most of the reports [10, 61] describe a shorter operative time for a thoracoscopic esophagectomy in PP than in LDP. As we have said before, the best exposure of the surgical field allows

Fabian et al. [64] suggested that the learning curve for the prone position approach appears to be relatively short, within the first five cases. This author also says that prone approach may result in better dissection into the neck explained by pneumatic dissection from the thoracic cavity cranially along the esophagus. This maneuver simplifies the neck surgery that could

The incidence of complications, such as anastomosis leak, gastric tip necrosis, chylothorax, tracheal, or vocal cord injury is comparable between PP and LDP according to many reports. Other clinical outcomes seem to be similar between both: median length of stay, discharged within 10 days, and in-hospital mortality [63, 64]. As we have commented at the beginning, it

In addition, in PP the surgeon's wrist and shoulder joins are in a neutral position in relation to the forearms and upper arms, minimizing fatigue and maximizing ergonomic function. The view of the monitor stands parallel to operative field and ergonomic position of the surgeon makes easier hand-eye coordination. In contrast in LDP, the surgeon's view of the monitor

might be possible to reduce respiratory morbidity using PP approach.

surgical field.

48 Esophageal Abnormalities

and decreasing bleeding.

for faster and better quality surgery.

lead to less morbidity in cervical step.

One disadvantage with the prone technique could be the need for conversion to open required electively when many adhesions preclude a minimally invasive approach or emergently as a consequence of uncontrollable bleeding. Although a posterior thoracotomy can be performed in this position, it is a less familiar approach that hinders dissection. Moreover, if we have performed the thoracic step without the use of a double-lumen endotracheal tube, we have to know that if a conversion is required, isolated lung ventilation would be invaluable. Thus, there are authors that continue using double-lumen intubation in the prone approach [64].

In conclusion, the PP may be performed with comparable outcomes to the LDP. The technique improves exposure of the operative field and reduces surgical times without compromising patient's safety or oncological results. Moreover, PP brings on an ergonomic position for the surgeon that makes easy the dissection.
