**4. Anesthetic challenges of MIE**

The anesthetic challenges of MIE include prolonged surgery, difficulties of lung isolation, and one lung ventilation (OLV) when patient is positioned right up and complications related to extraperitoneal CO2 . Pain relief has been described as a protective factor to avoid postoperative respiratory complications, so it is highly recommended to use regional techniques for reducing postoperative pain. Also, the amount of fluids administered perioperatively can lead to the development of pulmonary complications and should be adequately evaluated to avoid fluid overload.

#### **4.1. Prolonged surgery**

MIE is a long procedure and may extend at least 5–6 h, depending on the experience of the surgeon. Such prolonged surgery increases the risk of hypothermia which can lead to reduce oxygen delivery and increase myocardial work, stress response, and postoperative infection. Our main objective is to maintain normothermia. If at the end of the surgery the patient is normothermic, extubation will be possible and postoperative ventilation will not be necessary [27].

Balanced anesthesia, by an inhalation approach (sevoflurane and desflurane) or by propofol target-controlled infusion with remifentanil, may help promote early recovery after MIE. There is evidence that both sevoflurane and desflurane, when compared with propofol, produce a beneficial local immunomodulatory effect in patients undergoing OLV for thoracic surgery, significantly reducing inflammatory mediators, adverse postoperative events, and improving clinical outcomes [28, 29].

#### **4.2. One lung ventilation**

MIE with a patient in right up position requires a period of one lung ventilation during the mobilization of thoracic esophagus. Inadequately managed lung isolation contributes to mortality and morbidity [30].

When surgery is performed thoracoscopically, retraction of an inadequately collapsed lung or lobe results more difficult than in open surgery, and this is important when choosing the method used to achieve lung isolation. The options described to reach an adequate lung isolation are a left or right double lumen tube or a single lumen tracheal tube and a bronchial blocker. A retrospective study has not found differences in intraoperative hypoxemia, hypercapnia, and high airway pressures whether a left- or right-sided tube was placed for OLV [31]. As a consequence most MIE techniques involve access to the right thorax; a left double-lumen tube perhaps would be preferable, especially when the thoracic approach is done in lateral decubitus. If we used the prone position (PP), a single-lumen endotraqueal tube is a valid alternative. Whichever method of lung isolation is selected, a fiberoptic bronchoscope should be used to check correct positioning both after intubation and after moving the patient before surgery [32].

The combination of OLV and esophageal surgery results in an inflammatory response that will increase alveolar injury, leading to the development of acute lung injury (ALI) [33]. During and after OLV, the alveolar concentrations of IL-6 and IL-8 are increased. The lung protective ventilatory strategy can reduce airway pressure and airway resistance. It can decrease the release of IL-6 and IL-8 and inhibit lung inflammatory response during OLV and postoperatively [34]. Some of the consequences that may cause ventilator-induced lung injury are volutrauma (high tidal volume), barotrauma (excessive transpulmonary pressure), atelectrauma (repeated opening and closing of alveoli resulting), and biotrauma (caused by inflammatory mediators) [35].

Thus, it is essential for the implementation of protective ventilatory strategies to reduce the severity of lung injuries during mechanical ventilation. These strategies include restrict tidal volume to 5–6 ml/kg during OLV, optimizing positive expiratory end pressure (PEEP), and limiting plateau and peak inspiratory pressures to less than 25 cm H2 O and less than 35 cm H2 O, respectively [36]. In addition to reduce lung injury, these actions promote early extubation [37].

#### **4.3. Complications of extra-peritoneal carbon dioxide**

• Patients who have a Forced Expiratory Volume in one second (FEV 1) < 70% of the predicted normal in the pulmonary function tests with normal arterial gas blood measurements are considered of moderate risk and those with FEV 1 < 50% or if the arterial gas bold analysis show hypoxemia or carbon dioxide retention must be considered of high risk.

The anesthetic challenges of MIE include prolonged surgery, difficulties of lung isolation, and one lung ventilation (OLV) when patient is positioned right up and complications related

erative respiratory complications, so it is highly recommended to use regional techniques for reducing postoperative pain. Also, the amount of fluids administered perioperatively can lead to the development of pulmonary complications and should be adequately evaluated to

MIE is a long procedure and may extend at least 5–6 h, depending on the experience of the surgeon. Such prolonged surgery increases the risk of hypothermia which can lead to reduce oxygen delivery and increase myocardial work, stress response, and postoperative infection. Our main objective is to maintain normothermia. If at the end of the surgery the patient is normothermic, extubation will be possible and postoperative ventilation will not be necessary [27]. Balanced anesthesia, by an inhalation approach (sevoflurane and desflurane) or by propofol target-controlled infusion with remifentanil, may help promote early recovery after MIE. There is evidence that both sevoflurane and desflurane, when compared with propofol, produce a beneficial local immunomodulatory effect in patients undergoing OLV for thoracic surgery, significantly reducing inflammatory mediators, adverse postoperative events, and

MIE with a patient in right up position requires a period of one lung ventilation during the mobilization of thoracic esophagus. Inadequately managed lung isolation contributes to mor-

When surgery is performed thoracoscopically, retraction of an inadequately collapsed lung or lobe results more difficult than in open surgery, and this is important when choosing the method used to achieve lung isolation. The options described to reach an adequate lung isolation are a left or right double lumen tube or a single lumen tracheal tube and a bronchial blocker. A retrospective study has not found differences in intraoperative hypoxemia, hypercapnia, and high airway pressures whether a left- or right-sided tube was placed for OLV [31].

. Pain relief has been described as a protective factor to avoid postop-

• Patients with Child C stage cirrhosis must not be eligible for surgery.

**4. Anesthetic challenges of MIE**

to extraperitoneal CO2

38 Esophageal Abnormalities

avoid fluid overload.

**4.1. Prolonged surgery**

improving clinical outcomes [28, 29].

**4.2. One lung ventilation**

tality and morbidity [30].

MIE may require a large period of capnoperitoneum, while laparoscopic dissection and mobilization of the stomach are being performed. As a consequence of surgical communication between the chest and abdomen, carbon dioxide may pass into the right chest, where drain tube has been placed in thoracic step, and this gas can be vented by this drain. In this situation, laparoscopic abdominal dissection could be difficult. Moreover, carbon dioxide may diffuse into the mediastinum (capnomediastinum), into the left chest, and it can cause subcutaneous emphysema around the chest, axilla, and neck. We can realize that gas is spreading to these spaces if we object a rapid increase in end-tidal CO2 . If CO2 is accumulated inside thorax cavity, an increase of airway pressures and lung compression might occur, leading to oxygen desaturation. This fact could negatively affect cardiac output.

We can solve all these problems by reducing the pressure at which the capnoperitoneum is maintained, and this will reduce the diffusion of gas to thoracic cavity without impairing abdominal dissection. Anyway, if extra-abdominal CO2 compromises cardiac or respiratory function, the capnoperitoneum should be evacuated. We should not extubate patients with significant emphysema until we achieve normocarbia [27].

#### **4.4. Fluid management—goal directed therapy (GDT)**

Maintaining adequate fluid balance is essential in both open surgery and MIE. While excessive fluid administration may be associated with increased postoperative pulmonary complication, tissue edema, and compromised perfusion, an inadequate intravascular volume can predispose to ischemia, end-organ dysfunction, and risk of anastomotic failure and leak.

In esophagectomy patients, an accurate fluid balance is essential to achieve adequate perfusion pressure and oxygen delivery to vital organs. The form of fluid replacement therapy, which is currently recommended, seems to be based on the principles of goal-directed therapy (GDT) with the aim to increase cardiac output in high-risk surgical patients. Various studies have found that GDT-based fluid administration improves intraoperative hemodynamic stability and reduces intensive care unit admissions, the incidence of complications, and mortality [38].

Some authors have suggested that restrictive fluid therapy is preferable to fluid overload because it leads to improved gastrointestinal recovery time, reduced overall morbidity [39], improved respiratory parameters, decreased incidence of postoperative pulmonary complications and shorter recovery periods [40]. On the other hand, fluid overload causes lung injury and has negatively impact to intestinal anastomoses [41].

#### **4.5. Thoracic epidural analgesia (TEA) versus paravertebral analgesia**

Even with reduction in trauma access, MIE may still result in an important postoperative pain, and optimal multimodal analgesia is required. Effective analgesia accelerates extubation, recovery, and early mobilization. Despite the importance of regular postoperative simple analgesia, a regional technique is essential.

Thoracic epidural analgesia (TEA) offers many benefits in esophagectomy, reducing respiratory complications, such us pneumonia [42–44] and postoperative pain. TEA has also been associated with decreased incidence of anastomotic leakage [37], possibly as a consequence of improving microcirculation in the gastric conduit [45]. Moreover, epidural analgesia also decreases the risk of prolonged ventilation or reintubation and improves some lung function parameters and blood oxygenation [46]. However, TEA also has some disadvantages: the incidence of failure may reach 12%, there are risks in the application technique, and it does not only promote urinary retention but also cause hypotension which makes necessary additional fluid administration [47–49]. Contraindications to an epidural access include sepsis or bacteraemia, infection at the insertion site, hypovolemia or shock, coagulopathy or thrombocytopenia and increased intracranial pressure [50].

Paravertebral blockade has recently been shown to provide analgesia comparable with TEA after thoracic step of esophagectomy. It is associated with less incidence of failed block and reduces hypotension and urinary retention when it is compared with TEA. Several recent reviews and meta-analyses defend its benefits [51–53], and it is a standard practice in some UK hospitals for minimally invasive esophagectomy. Local data also show shorter stays in the intensive therapy unit comparing with TEA.

#### **4.6. Conclusion**

MIE supposes many anesthetic challenges, some of them unique for this type of procedure and requires an accurate knowledge of the different surgical steps performed. Moreover, it is essential to know and treat complications of one lung anesthesia and extra-peritoneal spread of CO2 . Paravertebral blockade might have more benefits than TEA to improve postoperative pain in patients undergoing for MIE.
