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Robotic thoracic surgery
Introduction
The minimally invasive journey in thoracic surgery now includes robotics. This has largely been dominated by the da Vinci platform, although newer devices from Johnson & Johnson, Cambridge, Medronic, and others have emerged. The versatility and considerable improvements in vision and instrumentation have led to the development of robotics in thoracic surgery. This applies to both standard open as well as already established video-assisted thoracoscopy surgery (VATS) operations. The utility of robotic techniques has also allowed for creativeness with operations once deemed ill-advised, even dangerous, to be attempted minimally invasively. These are now possible with robotics.
Thoracic surgery with robotics can be divided into three categories—pulmonary surgery, mediastinal surgery, and a collection of other procedures which should be best considered separately. The pathologies for these categories are quite separate and the organs involved again are distinct.
Thoracic surgical approaches and incisions can vary considerably. The standard lateral decubitus position is the mainstay of most thoracic surgical procedures; however, supine, semisupine, cervical, or subdiaphragmatic approaches are often utilized. Large posterolateral thoracotomies, smaller muscle-sparing thoracotomies, multiport and uniportal VATS approaches are all popular in modern practice. Similarly, when applying robotics, no single approach or technical workflow has become the standard of care. The techniques described in this chapter will seek to describe the most common approach and technique for each category.
The minimally invasive approach in thoracic surgery is perhaps unique in as much as port placement can significantly influence the ability to successfully complete the procedure. Access and assistant ports also must be carefully considered as the intercostal spaces are not movable when compared to abdominal and pelvic procedures.
All thoracic procedures generally require single lung ventilation with a double-lumen tube. While gas insufflation is routinely used, lung isolation is preferred and is often necessary, especially in pulmonary resection. Insufflation alone has been described for nonlung surgery but is not advised, as higher gas pressures may be required which can result in unsafe intrathoracic pressures compromising venous return.
Group B—the anterior mediastinum
This category involves diseases of the anterior mediastinum ( Table 64.2 ). The most common organ of interest to the thoracic surgeon is the thymus. Tumors of the thymus consist mostly of thymoma and thymic carcinoma. Other less common tumors of the anterior mediastinum include teratoma, germ cell tumors, carcinoid tumors as well as cysts arising from the thymus, pericardium, bronchus and esophagus. Rarer tumors must be considered carefully for surgery as a preoperative tissue diagnosis is not always possible. Tumors involving vascular, pericardial, and neural structures require planning as catastrophic bleeding can take time to control with a docked robot.
TABLE 64.2
The Anterior Mediastinum
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Surgery for myasthenia gravis is particularly well-suited to a robotic approach, as extended ports to remove tumors are not required. Furthermore, the brittle myasthenic patient will have less risk of myasthenic crisis if sternotomy or other open more painful and stress-inducing approaches can be avoided.
The overwhelming majority of surgery for the anterior mediastinum requires access to BOTH pleural cavities as opposed to lung or posterior mediastinal operations. For oncological correctness, the entire thymus has been the gold standard, although recent evidence supports thymomectomy for small contained tumors The favored positioning of these patients in our experience is a semisupine position. The laterality is usually dictated by the tumor, i.e., a thymoma which is predominantly right-sided is best tackled via the right chest. For nonthymomatous myasthenia gravis patients approach from either side is possible but we feel that the left affords a better view of the innominate vein. The technical aspects of the surgery are the same.
Group A—pulmonary surgery
Robotics is now well-established in minimally invasive pulmonary resections ( Table 64.1 ) with significant surgical case series worldwide being published. Both success in surgery and oncological outcomes are comparable to other techniques with many surgeons using a robot for all their lung surgery. During development (and also in training), simpler cases were adopted for the robot given that there was less chance for surgical mishap and requirement for conversion. More complex procedures including sleeve resections (both bronchial and vascular), chest wall resections, and, notably, pulmonary segmentectomy are now performed routinely by the experienced thoracic robotic proponent claiming that the more difficult technical maneuvers are easier with better vision and instrument dexterity. Improved preoperative planning using 3D vascular reconstructions which can be viewed directly inside the robot (Xi) have enabled the increased uptake of robotic pulmonary segmentectomy. In terms of training, a team approach is necessary as the table-side surgeon/assistant requires specific training and skills using staplers and other surgical instruments. Interestingly, many nonminimally invasive surgeons have found the transition from open surgery to robotics much simpler than those transitioning from VATS.
TABLE 64.1
Pulmonary Resection
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Group C—the posterior mediastinum
The posterior mediastinum category includes various other thoracic conditions and pathologies where robotics can be applied ( Table 64.3 ). Most commonly, this includes tumors of the posterior mediastinum and surgery for the diaphragm. A wide variety of tumors are encountered here—largely of neurogenic origin. They can occur from the apex of the chest where the brachial plexus and thoracic inlet vasculature must be considered to the inferior reaches of the costodiaphragmatic which demands an entirely different anatomical direction for the robotic surgeon.
TABLE 64.3
The Posterior Mediastinum Surgeries
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Careful port placement and positioning of the robot cart as well as patient positioning are therefore important. Choice of instrumentation (i.e., monopolar vs. bipolar energy) can also vary depending on whether the surgical object is cystic or solid, and its relationship to the neural foramina and dural sheath.
Surgery for the diaphragm is utilized for symptomatic diaphragmatic eventration and a short list of other uncommon conditions. The use of insufflation is useful in all intracavitary robotic procedures but few more so than surgery on the diaphragm which flattens the often marked domed position of the diaphragm. This simple addition of insufflation adds great utility to diaphragmatic procedures, but care must be taken not to compromise venous return with high flow/low pressure gas.
Preoperative assessment
Thoracic surgery, regardless of approach or pathology, is deemed major surgery and hence deserves a thorough assessment of the patient’s physiology. Differing indications will call for specific tests such as pulmonary function testing for lung resections, but all patients will require careful evaluation of comorbid conditions and screening for major disease, especially cardiac conditions.
General preoperative assessment
Regardless of the approach and method of the surgical procedure, the key fundamentals for preoperative assessment apply. It is important to assess the initial basic principles with history taking and patient examination relevant to the surgery taking place. This in combination with a review by the anesthetic team will help decide fitness for surgery.
Thoracic surgery-specific considerations
Preoperative assessment in thoracic surgery, and particularly pulmonary resection, plays the same role when comparing VATS to robotic surgery. The main predictors that outline preoperative assessment lie within functional testing as well as preexisting modifiable and nonmodifiable risk factors. Functional testing generally consists of spirometry and diffusion capacity, 6-minute walk testing, and cardiopulmonary exercise tests (CPETs).
Spirometry and diffusion capacity
Pulmonary function testing is simple noninvasive analysis of respiratory status and function, and it is one of the first tests used to evaluate patient selection for surgical suitability following careful clinical evaluation.
FEV 1 , a measure of the ability to expire lung volume over 1 second, is used as part of the measure, along with diffusing capacity for carbon monoxide (DLCO), to assess patients’ suitability for pulmonary resection and fitness for surgery. Generally, the preoperative FEV 1 should be greater than 80% pred and there should not be signs of interstitial lung disease or airflow obstruction prior to proceeding without any further studies conducted ( Fig. 64.1 ).
DLCO, also known as the TLCO, is a measurement of the transfer of CO molecules from alveolar gas to the uptake by the hemoglobin molecules by red blood cells. In pulmonary surgery, it is deemed a good measure and predictor for proceeding to surgical anatomic resection. Guidelines currently used in practice have identified that DLCO greater than 80% can be used to identify patients with a normal pulmonary function in whom no additional tests are needed. A DLCO less than 60% in current practice leads to patients needing to undergo further functional assessment to assess fitness for surgery.
Exercise testing
Exercise testing is used to test the anaerobic threshold (AT) under a degree of stress and this can be broken down into three different testing regimes: 6-minute walk test, stair climb test, and shuttle walk test, all expanding in different ways to assess their aerobic capacity. The shuttle walk test and stair climb test both have fixed points of measurements and hence have the ability to be regulated and applied to the level of a patient’s fitness and AT.
Cardiopulmonary exercise tests
When primary testing has been completed and there are concerns of a high-risk cardiac evaluation (i.e., low % FEV 1 or DLCO less than 30% or a 6-minute walk test less than 400 m), then cardiopulmonary exercise testing should be conducted ( Fig. 64.2 ). Cardiopulmonary exercise testing is a form of function assessment that is used to predict oxygen cardiopulmonary reserve. CPET testing has been shown to better predict postoperative complication and mortality compared to resting cardiac investigations and pulmonary function testing. CPET allows estimation of the maximal oxygen uptake (VO 2 max) during exercise, which correlates to aerobic capacity and cardiorespiratory fitness. ,
Results from CPET testing which help guide operative planning are the maximum aerobic capacity (VO 2 max) and the AT. VO 2 max suggests the practical limit of cardio/respiratory response to exercise and stress. Predicted values can be calculated based on gender, age, and height :
Predicted values greater than 20 mL/kg/min is suggestive of a favorable outcome and patients with VO 2 max less than 10 mL/kg/min are very high-risk candidates for pulmonary resection.
The anabolic threshold is the onset of oxygen demand and supply mismatch in muscles leading to anaerobic metabolism and lactic acidosis.
Cardiac testing
When assessing any patient for thoracic anatomical resection, along with their intrinsic pulmonary function, it is vital to assess the strain on the entire cardiovascular system. However, tests mentioned above will indicate if further cardiac testing will need to take place. Initially a standard transthoracic echocardiogram (TTE), or in higher risk patients a stress TTE, looking for the right heart function is a good indicator for an individual’s intrinsic pulmonary resistance to further guide the strain on the heart if further lung parenchyma were to be resected.
If pulmonary pressure is elevated and surgical resection is still favored as the only form of treatment available, a dedicated quantitative ventilation perfusion scan can further guide and assess lung dependency to see if it would be affected after further surgical resection.
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