Overview of minimally invasive thoracic surgery

INTRODUCTION — Video-assisted thoracoscopic surgery (VATS) is a set of minimally invasive thoracic surgical (MITS) procedures used to diagnose or treat conditions of the chest (pulmonary, mediastinal, chest wall). Most major procedures traditionally performed with open thoracotomy can be performed using smaller incisions with video assistance. A related technology, robotic-assisted thoracic surgery (RATS), uses computers to aid surgeon instrument control. The essential difference between VATS and RATS is that with VATS, the surgeon holds the instruments, whereas with RATS, the surgeon controls the instruments from the console and does not directly handle the instruments but does directly control all aspects of the instruments' movement. In this topic review, we will use the broader term MITS to include VATS and RATS, using individual terms when specifically needed.

MITS provides safe, effective, and successful surgery when patients are selected appropriately. The indications have expanded as technology has improved. Continued outcome assessments are needed to ensure that MITS provides equivalent or improved outcomes compared with traditional open surgical methods. Quality of life assessments, morbidity rates, and recovery timelines also are important factors for comparison. Although few trials exist, many observational studies indicate that MITS has less perioperative morbidity and equivalent oncologic results compared with open operations. For special populations, such as frail and older adult patients, outcomes may be better. Generally, perioperative costs for minimally invasive procedures (both VATS and RATS) are higher because of the equipment. However, overall costs may be lower due to shorter length of stay and faster patient recovery.

The diagnostic and therapeutic uses of MITS, including an overview of the indications, the preoperative evaluation, procedures, perioperative care, and surgical outcomes, are reviewed here. Anesthesia for minimally invasive thoracic surgery is reviewed separately. (See "Anesthesia for video-assisted thoracoscopic surgery (VATS) for pulmonary resection".)

THORACOSCOPIC SURGERY — In the same manner in which laparoscopic techniques reduce the need for large abdominal incisions, minimally invasive thoracic surgery (MITS) eliminates the need for thoracotomy that requires spreading of the ribs (figure 1) or sternotomy incisions (figure 2).

MITS uses a thoracoscope attached to a video camera to see into the chest. The lens and the instruments necessary to perform the surgery are inserted between the ribs and into the chest cavity through one or multiple small incisions. The basic principles used in open thoracic surgery (exposure, traction, countertraction) govern MITS as well, but the surgeon's hands remain outside of the chest cavity (or, in the case of robotic surgery, at a separate console), to manipulate and work the end of the instruments, which are located inside the chest.

The prevalence of video-assisted thoracoscopic surgery (VATS) for more complex procedures has been steadily increasing, primarily because of reduced complication and mortality rates, particularly among frail patients [1]. In dedicated general thoracic centers, the use of VATS is approaching or has even surpassed open thoracotomy for pulmonary lobectomy. Tracking from the Society of Thoracic Surgeons General Thoracic Surgery Database (STS GTSD) showed an increase in VATS anatomic lung resection (lobectomy and segmentectomy) from 8 percent in 2003 to 43 percent in 2009 from all participating centers [2]. An updated analysis showed that MITS usage (ie, VATS and robotic-assisted thoracic surgery [RATS]) climbed to 62 percent [3], with such cases having fewer complications, decreased length of stay, and decreased chest tube duration in database analyses or case series [4-6].

Terminology — The use of the term "video-assisted thoracoscopic/thoracic surgery" (ie, "VATS") is applied to multiple similar, but not identical, methods. There is variability in the placement, size, and number of the incisions (also called ports) and the extent of usage of the thoracoscope that is used to accomplish the surgery. To avoid instrument conflict, ports are optimally spaced 8 to 10 cm apart, and the largest (utility) incision is generally placed within an interspace that is wide enough to allow multiple instruments to be passed and for the specimen to be extracted.

The terms "VATS" and "thoracoscopy" are often used interchangeably but are not always equivalent. A rough comparison of VATS and RATS approaches is given in the table (table 1).

●VATS uses an access (or utility) incision that ranges from 2.5 to 8 cm in length and allows manipulation of multiple traditional or thoracoscopic instruments through the same incision at the same time. VATS can be performed with one (uniportal) or up to four chest incisions (figure 3). The position of the incisions varies depending upon surgeon preference or procedure being performed.

●"Totally thoracoscopic" or "completely thoracoscopic" or "totally portal" procedures use ports that are only large enough to admit a trocar without the use of an access or utility incision. This facilitates insufflation with carbon dioxide to maintain exposure but may require enlargement of one incision to extract specimens.

●The other method of minimally invasive surgery in the chest is robotic-assisted thoracoscopic surgery (RATS). RATS uses a unit that has multiple movable arms controlled by the surgeon at a separate ergonomic console, as currently there is only one intracorporeal robotic system for use in humans approved for use in the United States. Robotic systems are more properly referred to as Computer-Aided Surgical Systems (CASS) because there is essentially no robot movement without human guidance. The arms of the robot are fitted with trocars through which pass interchangeable slim instruments, including a video camera with three-dimensional optics. Excluding the camera arm, either two or three arms are used during RATS. Insufflation with carbon dioxide (CO₂) is usually used during RATS to aid in creation of space in the pleural or mediastinal cavity. Assistants are needed at the bedside to exchange robotic instruments in and out of the robotic arms and trocars.

●Hand-assisted thoracoscopy uses a small thoracotomy that allows passage of the surgeon's hand in conjunction with imaging provided with a thoracoscope. During surgery, carbon dioxide insufflation facilitates soft tissue dissection and increases the domain of the chest by depressing the diaphragm [7-9]. A device that has a cap may be inserted into a small access incision while maintaining an airtight seal to allow passage of instruments and/or the surgeon's hand for palpation or dissection.

Learning curve and credentialing — The steep learning curve for performing MITS procedures more complex than pulmonary wedge resections, pleural biopsies, and hemothorax or empyema evacuation requires frequent repetition in temporal continuity and is hindered if case volume is low. Acquisition of these skills requires patience and persistence on the part of the surgeon learning these techniques. This particularly applies to the surgeon who trained before the era of widespread use of laparoscopy; learning these techniques with the benefit of a proctor can alleviate many missteps.

In a report that analyzed data for MITS from the American College of Surgeons (ACS) National Cancer Database between 2010 and 2012, VATS for lung lobectomy was used in only 26 percent of all lobectomies, and RATS lobectomy accounted for 6.7 percent [10]. A later report showed that general adoption of MITS for lobectomy was highly dependent on surgeon specialty (general thoracic surgeon highest), location (Northeast United States highest), and case density of the surgeon (>15 per year) [11]. Similarly, general thoracic surgeons predominated with a higher RATS rate (14 percent) [12]. Reasons for the low percentage of MITS lobectomy are multifactorial, including the steep learning curve, lack of availability of equipment and instrumentation, lack of adequate operative assistance, low caseload of thoracic procedures in usual practice, and for some, a staunch belief in the superiority of open procedures.

Each institution or hospital system at which a surgeon requests operative privileges has credentialing and privileging requirements that need to be satisfied and generally require a minimum annual case volume, demonstration of training, and mentoring of initial cases by intramural or external experts. The American Board of Thoracic Surgery (ABTS) requires residents who started their cardiothoracic training on or after July 1, 2017, to include 5 or 25 major VATS/robotic anatomic resections for cardiac-focused or thoracic-focused residents, respectively [13]. In an anonymous survey, younger cardiothoracic surgeons included robotic cardiac surgery and robotic lung resection as areas where they felt technically less confident. There is currently no requirement from the ABTS regarding a minimum number of robotic-assisted cases [14]. An International VATS Lobectomy Consensus Group provided guidelines for defining technical proficiency for VATS lobectomy recommending performance of 50 cases with a minimum of 20 VATS lobectomy cases performed annually to maintain competency [15]. Residency training centers under these guidelines should be able to provide 50 VATS lobectomy cases annually.

Although no formal guidelines or certifications for the performance of MITS lobectomy exist for already practicing certified surgeons, proctoring is highly recommended after the initial steps mentioned above to ensure a safe transition from open surgical techniques. Learning experiences are offered from experts around the world:

●Half-day didactic and hands-on courses with manikins or simulators at cardiothoracic surgery conferences such as the Society of Thoracic Surgeons [16]

●Two- to three-day didactic, case observation, and hands-on courses with manikins, simulators, or animate labs at institutions with high volume

●High-intensity two-week didactic, case observation, hands-on course with animate labs at extremely high-volume international centers [17]

Anatomic considerations — Port placement, instrumentation, and quality of equipment can have a large impact on the safety and ease with which complex thoracoscopic procedures are completed. A sound knowledge of chest and pulmonary anatomy (figure 4) facilitates understanding the three-dimensional relationships of the structures of the chest and mediastinum with the two-dimensional view of thoracoscopy. (See "Overview of pulmonary resection" and "Overview of pulmonary resection", section on 'Anatomy and bronchopulmonary segments'.)

Chest structures that are accessible by thoracoscopy include the lungs, esophagus, pleura, diaphragm, pericardium, heart, thymus, anterior and lateral spine, sympathetic chain, thoracic duct, and mediastinal structures.

Compared with laparoscopic surgery in the abdominal cavity, the thoracic cavity provides some challenges but also some advantages. The chest cavity and the mediastinum are smaller than the peritoneal cavity, and incision placement needs to be planned carefully, taking into account the position of the patient's ribs, arm, diaphragm, and scapula. The chest has a more rigid structure and does not routinely require insufflation, but insufflation with carbon dioxide using airtight trocars is an option. Unlike the abdomen, insufflation is ineffective for expanding the overall size of the rigid thoracic cavity, but it can help compress a suboptimally deflated ipsilateral lung and help depress the diaphragm to increase relative operative working space. Avoiding insufflation allows the use of standard instruments or multiple low-profile tools through a single port, which can be an advantage.

INDICATIONS — Minimally invasive approaches can be used for the diagnosis or treatment of benign or malignant chest diseases. Many procedures historically performed as an open thoracotomy are now performed as video-assisted thoracoscopic surgery (VATS). As surgeons become more proficient and technological advances in optics and instrumentation occur, the number and complexity of diseases/problems that can be safely and reliably diagnosed or treated by thoracoscopy are growing.

Diagnostic thoracoscopy — Thoracoscopy was initially used mainly as a diagnostic tool until the 1970s for pleural diseases, particularly for tuberculosis [18-20]. Basic single-port diagnostic thoracoscopy may also be referred to as pleuroscopy and has also been referred to as "medical thoracoscopy." Medical thoracoscopy is often performed with monitored anesthesia care with the avoidance of general anesthesia. A semiflexible pleuroscope has a channel in the shaft of the scope for passage of biopsy forceps (figure 5). (See "Medical thoracoscopy (pleuroscopy): Equipment, procedure, and complications".)

For diagnostic purposes, pulmonologists, general surgeons, trauma surgeons, and thoracic surgeons may use thoracoscopy to visually inspect the structures of the chest or to obtain fluid or tissue for histologic examination or cultures [19,21,22]. Pleural biopsy is one of the earliest procedures for which diagnostic thoracoscopy was used (picture 1). A variety of other tissues can be accessed for inspection or biopsy (eg, mediastinal nodes, diaphragm, lung parenchyma, pericardium, and esophagus) sometimes with greater ease compared with an open surgical, percutaneous, or endobronchial approach [23-26]. Also, if malignant pleural disease is discovered, thoracoscopy can guide pleurodesis or a placement of a drainage catheter. (See "Approach to the adult patient with a mediastinal mass" and "Surgical evaluation of mediastinal lymphadenopathy" and "Procedures for tissue biopsy in patients with suspected non-small cell lung cancer".)

The use of robotic surgery for diagnosis may increase in the future [27]. Uniportal robotic surgeries are being reported in the literature with many companies also developing robotic platforms [28,29]. (See 'VATS versus RATS' below.)

Therapeutic MITS — Therapeutic minimally invasive thoracic surgery (MITS) slowly gained momentum in the 1990s after the success of laparoscopic operations such as cholecystectomy. MITS can be used to treat many conditions that have predominantly been managed using open surgery, including a variety of pulmonary, cardiac, pleural, mediastinal, esophageal, chest wall, and spinal problems. VATS has been used for tissue resection (eg, lobectomy, esophagectomy, thymectomy, sympathectomy) [24,30-47], therapeutic drainage or pleurodesis [23,48-51], and reconstruction (diaphragmatic plication, diaphragmatic hernia repair, chest wall reconstruction) [24,25,34,37,52-57]. Robotic-assisted thoracic surgery (RATS) is another option for any of the procedures performed by VATS that would benefit from the three-dimensional binocular vision and wristed movements provided by the robotic platform, such as mediastinal cyst excision and lymph node removal, which require dissection from small, tight, irregularly shaped spaces adjacent to vital structures, and also for procedures that require suturing, such as bronchoplasty or diaphragmatic plication [58].

The most common uses for therapeutic MITS include the following:

Pulmonary resection — Pulmonary resection is used for the treatment of a variety of diseases, including primary lung malignancy, metastatic disease to the lung, a variety of benign lung diseases when medical therapies are no longer effective, and more severe traumatic injuries. In addition, pulmonary resection is also a means of diagnosis for some pulmonary diseases. (See "Overview of pulmonary resection".)

Enough time and experience with MITS lobectomy has elapsed, and randomized and observational trials suggest equivalence, if not superiority, for minimally invasive compared with open pulmonary resection [59-63].

●A meta-analysis comparing VATS, RATS, and open lobectomy reported that RATS took more time, but it was associated with less morbidity and mortality compared with VATS or open lobectomy [61].

●In a comparison of MITS and open lobectomy, MITS was oncologically equivalent to thoracotomy for early-stage non-small cell lung cancer lymph node sampling and overall survival [59]. Similar overall and cancer-specific survival of non-small cell lung cancer was found by a propensity matched study of RATS and VATS lobectomy using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database [64]. The VIdeo assisted thoracoscopic lobectomy versus conventional Open LobEcTomy for lung cancer (VIOLET) trial from the United Kingdom showed that VATS lobectomy reported better physical function at five weeks, less prolonged pain, less in-hospital morbidity, and equivalent oncologic outcome compared with lobectomy performed by open thoracotomy [65,66].

●In a Danish trial, although MITS anatomic lung resection has higher operative costs compared with open lobectomy, the cost savings due to decreased length of hospital stay and lower readmission rate was economically advantageous [67]. A propensity-matched study comparing RATS and VATS lobectomy at high-volume centers showed longer operative time by 25 minutes, but lower conversion to thoracotomy rate and lower complication rate [62].

Pleural disease/chest cavity — Pleural drainages (pneumothorax, hemothorax, empyema, malignant pleural effusion) with mechanical or chemical pleurodesis are approached commonly using thoracoscopy. MITS decortications can be tedious depending upon the chronicity of the empyema or hemothorax [68-70]. Experience and judgement, appearance of the radiologic studies, and the patient's clinical course all contribute to the decision of whether to attempt these by minimally invasive incisions versus open thoracotomy. Robotic decortication is being performed, and the wristed arm movement and use of CO₂ can be an advantage for division of adhesions and pleural debridement. (See "Management of malignant pleural effusions" and "Initial management of malignant pleural mesothelioma".)

Diaphragm surgery — For patients with phrenic nerve paralysis, the diaphragm becomes lax and attenuated and rises in the pleural cavity, causing compressive atelectasis, mediastinal shift, or lobar collapse with resultant dyspnea. One technique that may be needed involves plicating or resection of the diaphragm, which expands the compressed lung and can be performed thoracoscopically or robotically. Thoracoscopic diaphragm plication improves pulmonary function testing with results that are comparable to those of open diaphragmatic plication. Increased use of RATS for diaphragm plication seems likely, particularly since suturing is markedly facilitated with the robotic platform. Insufflation with CO₂ also helps flatten the diaphragm, making thoracoscopic or robotic plication easier [71]. (See "Surgical treatment of phrenic nerve injury".)

Diaphragmatic injury can also be evaluated and repaired thoracoscopically, which is particularly helpful for repair of right-sided diaphragmatic rupture or hernia since the liver obscures the laparoscopic view [72-75]. Insufflation of the peritoneal cavity can occur, temporarily obscuring the field of view in the chest; however, the air can be evacuated from the peritoneal cavity by using a soft suction tube that can be removed once the diaphragm has been repaired. (See "Recognition and management of diaphragmatic injury in adults".)

Chest wall surgery — A minimally invasive approach to chest wall surgery has included treatment of chest wall deformities (eg, pectus), rib biopsy, and chest wall tumor resection. (See "Surgical management of chest wall tumors".)

Traditional methods of pectus excavatum repair once required complete or partial sternotomy, exposure and excision of costal cartilages, and sternal osteotomy or inversion. The Nuss procedure revolutionized pectus excavatum repair by using a minimally invasive technique to safely position a convex metal bar from one side of the chest to the other side (figure 6). The bar is then inverted 180°, exerting upward pressure on the concave sternum. The thoracoscope is more commonly placed on the right side but may be placed from the left side. Bilateral thoracoscopy may be necessary if the pectus is severe. Prior to use of thoracoscopy, cardiac perforation was reported but was rare [76]. Delayed complications include bar displacement and wound infection at the time of bar removal. (See "Pectus excavatum: Treatment".)

Esophageal surgery — MITS for benign diseases of the esophagus and mediastinum allows successful treatment using smaller incisions. Most esophageal pathologies that are amenable to a thoracoscopy (eg, excision of esophageal diverticulum (picture 2)) are approached from the right chest cavity; however, the more distal thoracic esophagus (eg, myotomy for achalasia (picture 3)) and the gastroesophageal junction (eg, distal esophageal carcinoma (figure 7 and movie 1)) leiomyoma (movie 2) can be approached either from the left chest cavity or laparoscopically [44,46,77-90]. For esophageal resection for malignancy, retrospective reviews have found similar numbers and locations of lymph nodes biopsied, less time to recovery, and less pain for MITS esophagectomy compared with open esophagectomy [84,91,92]. MITS is also associated with fewer complications (chiefly pulmonary), particularly when the anastomosis is in the chest [40,93,94]. Complications that are relatively rare with open esophagectomy, such as tracheogastric or bronchogastric fistula, are increased with MITS esophagectomy, and their recognition requires vigilance in the postoperative period [91]. (See "Surgical myotomy for achalasia" and "Local treatment for gastrointestinal stromal tumors, leiomyomas, and leiomyosarcomas of the gastrointestinal tract" and "Surgical management of resectable esophageal and esophagogastric junction cancers".)

Others

●Heart – Cardiac surgeries using thoracoscopy or robotics include coronary artery bypass grafting, atrial septal defect repair, resection of intracardiac tumors, mitral valve repair/replacement, ablation of atrial fibrillation, placement of epicardial pacemaker leads, and creation of a pericardial window [95-99]. The wristed motion of the robot is advantageous for cardiac surgeries that involve suturing and may allow elimination of mini-thoracotomy or sternotomy used with most thoracoscopic techniques. (See "Atrial fibrillation: Surgical ablation" and "Transcatheter aortic valve implantation: Periprocedural and postprocedural management" and 'Other procedures' below.)

●Spine – Spine procedures that can be accomplished using a minimally invasive approach include thoracoscopic laminectomy, disc decompression/debridement, and abscess drainage, typically by orthopedic spine surgeons or neurosurgeons. (See "Lumbar spinal stenosis: Treatment and prognosis" and "Subacute and chronic low back pain: Surgical treatment".)

Contraindications — To adequately see and have space to manipulate instruments within the pleural cavity, it is necessary to collapse the lung on the operative side by selectively ventilating the contralateral lung. The only absolute contraindications to VATS and RATS are the inability to achieve the working space needed or if a patient cannot tolerate one-lung ventilation (eg, airway mass, prior pulmonary resection, severe pulmonary disease). (See "One lung ventilation: General principles", section on 'Indications'.)

Selective ventilation is generally necessary to accomplish longer and more complex procedures. However, some simple procedures such as sympathectomy can be performed without single-lung ventilation and often without double-lumen endotracheal intubation. Others such as pleural biopsy or small lung wedge biopsy can be accomplished during brief periods of apnea, but double-lumen intubation is helpful to allow repeated inflation and deflation of the lung on the operative side with frequent communication with the anesthesia team. Bronchial blockers may also be used for single lung ventilation. Disadvantages include longer time for lung deflation and therefore less efficient ability for repeated inflation and deflation of the lung. The use of carbon dioxide (CO₂) insufflation to aid lung collapse can be advantageous for certain procedures. To maintain CO₂ based exposure, straight shaft laparoscopic instruments and gastight ports are needed.

It should be noted that there is an emerging trend (especially in Asia) to perform complex minimally invasive thoracic procedures using spontaneous patient ventilation without selective intubation strategies. This is only done with very careful patient selection, careful anesthesiologist monitoring, and use of local anesthesia to block reflex pathways during bronchial manipulations. Whether this will be safe for broad application is under study [100].

Severe adhesions in the chest cavity are a relative contraindication. Thoracoscopy can be attempted, but thick fibrotic adhesions that are difficult to divide obscure the view and increase the risk of injury to vessels or intrapleural/mediastinal structures and/or extend operative time. With complete fusion of the visceral and parietal pleura, there is no domain or operative workspace.

PATIENT SELECTION — Careful patient selection for complex minimally invasive thoracic surgical (MITS) procedures increases the likelihood of successful and safe completion. The operating surgeon should evaluate the patient anatomically and medically. Pulmonary function tests, including spirometry, lung volume measurements, and quantification of diffusing capacity, are performed preoperatively to identify high-risk patients who may not tolerate one-lung ventilation, which is necessary for most MITS procedures. (See 'Contraindications' above and "Evaluation of perioperative pulmonary risk" and "One lung ventilation: General principles" and "Overview of pulmonary resection", section on 'Preoperative evaluation and preparation'.)

Anatomic chest wall deformities or an elevated hemidiaphragm can limit optimal positioning or limit optimal access into the thorax and should be identified when considering video-assisted thoracoscopic surgery (VATS). Robotic surgery particularly requires adequate domain within the pleural space to allow optimal visualization and manipulation of the arms and instruments, although newer robotic configurations may remove these concerns in the future.

Manipulation of the thoracoscope and instruments through the chest wall will be easier in patients with normal or slender body habitus. Dissection may become difficult in obese patients as more adipose tissue obscures the normal planes between structures (figure 8) [101-103]. Intra-abdominal obesity also elevates the diaphragm and reduces volume of the thoracic cavity. One advantage of robotic surgery in this situation is that the robotic arms fulcrum the instruments around a fixed point such that once the trocars are in place, the thickness of the chest wall does not affect their mobility. The use of carbon dioxide insufflation during robotic surgery aids in depressing the diaphragm to provide more space in the pleural cavity.

Computed tomography (CT) of the chest should be also performed within six to eight weeks of MITS, particularly if the suspected disease is dynamic. The CT protocol depends upon the nature of the pathology being evaluated for resection or repair. (See "Overview of pulmonary resection", section on 'Preoperative lung imaging'.)

Lesions with surrounding inflammatory changes, such as an abscess, mycetoma, and/or those with dense adhesions including calcified lymph nodes, are challenging to excise and present a higher risk of trauma to adjacent structures. Inadvertent damage to major vessels or vital structures can result in excessive bleeding or loss of ventilatory control, requiring conversion to thoracotomy. Although conversion for bleeding during robotic surgery is logistically more challenging compared with thoracoscopy because of the presence of the robot, the most anterior robotic arm can be used to tamponade any bleeding with a rolled gauze, or the bedside assistant can control bleeding through their designated port with an instrument holding a gauze [104]. This provides time to remove the other robotic instruments and undock the free robotic arms to provide space for thoracotomy. Inflammatory lung changes also create edema and fibrosis, making it difficult to divide the lung or judge whether an anatomic margin is sufficiently remote from the lesion. MITS decortication of a fibrothorax can be challenging because of the thickness of the adhesions that form a parietal rind and limit viewing and working space in the pleural cavity.

In the setting of prior coronary artery bypass grafting with a patent internal thoracic artery conduit in proximity of the operative field, proper planning for MITS is essential. Preoperative imaging studies, such as CT angiography, assist in delineating the course of the internal mammary artery (IMA) graft in order to avoid iatrogenic damage and possible cardiac ischemia [105]. As with any thoracic operation that has the potential to jeopardize an IMA conduit, appropriate preparations should be made, including ensuring the availability of cardiac surgery backup, depending upon the anticipated risk [106].

EQUIPMENT — To avoid cancellations, frustration, and technical mishaps, it is important to check that necessary equipment and instruments are available prior to the procedure. Surgical technicians should be familiar with how equipment is prepared and maintained. Education and training for new equipment and instruments is necessary for safe and efficient use. In certain circumstances, having a company representative in the operating room can be helpful until all personnel are comfortable with the equipment.

Imaging — Technological advances for minimally invasive videoscopic viewing include increased picture definition and improved illumination. The following scope options can be used based upon surgeon preference and technique-specific anatomic needs:

●Two-dimensional (2D) versus three-dimensional (3D)

●Standard versus high-definition (up to 4K resolution)

●10 mm (standard) versus smaller, 5mm or 2mm

●Integrated (all-in-one) versus separately attached camera head

●Flexible versus fixed scopes with variable viewing angles

3D binocular viewing is not only available within the robot console but also with laparoscopic/thoracoscopic video systems (figure 9) [107-109]. These have reduced operative times for lobectomy [107]. Other technological innovations that are in progress include wireless video systems (alleviating the need for cords and small cameras) and lenses that can be mounted onto the chest wall, providing the ability to view from multiple vantage points simultaneously within the chest during procedure. Although 3D view is now available for video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracic surgery (RATS), the depth perception gained still does not provide the large field of view during dissection of structures such as those in the hilum that is afforded during a thoracotomy. A low threshold for conversion to thoracotomy or sternotomy is imperative to maintain patient safety during the learning curve.

Thoracoscopic lenses can be separate and interlock into a camera, or the lens and camera can be one integrated unit. (figure 10). Lenses can be entirely rigid or can have a flexible portion or a rotating prism that allows a range of angled views. Rigid lenses are sturdier and less prone to damage but require that several lenses be available to view different angles, while flexible lenses allow different viewing angles without the need to change lenses. VATS is facilitated by using a variety of lens angles, from 0 to 45°, for optimal visualization of the pleural and thoracic cavity (figure 11). Thoracoscopes are available in different widths, including 2- (needlescope), 3-, 5-, 8-, and 10-mm diameters, and are able to provide high-definition resolution and project enough illumination for excellent visualization, resolution, and magnification.

The video image is generally projected onto one or more monitors that are ideally suspended from the ceiling to allow optimal ergonomic positioning for the surgeon without conflict with floor-based equipment (figure 12). The number of monitors used depends on the surgical procedure and the number of operating surgeons. Typically, at a minimum, two monitors are used, one on each side of the table for the facing surgeon and assistant to view. Additional monitors facilitate preparedness and interactions by nursing and anesthesia personnel. High-definition resolution is an important adjunct that improves the visibility of structures within the chest or mediastinum by increasing clarity for precise dissection and reducing the need to zoom the camera to increase magnification. In addition to high-definition systems, the use of stereoscopic (3D) cameras has also improved the exposure and reduced the duration of more complex minimally invasive operations. While some newer monitors can display 3D images without the need for special eyewear, most medical 3D systems require the surgical team to wear glasses that enable such viewing [110]. The processing of images by the human mind is complex and quite variable [111,112]. As an example, some individuals are dependent on stereoscopic (3D) optics to judge depth and can use different cues such as shadowing to process 3D imagery, while a minority are "stereoblind." This helps explain the differences in popularity and adoption rates of certain minimally invasive platforms such as robotics that are based on integrated 3D optics.

Augmented reality systems are being developed to integrate video recording, take photographs, review patient information, and image during surgery. Overlay of fluorescent imaging, holograms, or 3D models onto the video monitor or the patient's real time anatomy is also being tried to assist with localizing anatomic structures [113,114].

Instrumentation — Many thoracic surgeons use the same instruments they would use for surgery through a thoracotomy incision. However, the use of open instruments may be hampered by the small length of the incisions, which do not accommodate the usual single-action ratcheting. Laparoscopic instruments can be used, but thoracoscopic equipment is generally shorter in length because the subcutaneous tissues and overall chest cavity depths are less. The shorter the instrument, the more control a surgeon has at the tip. For more complex procedures, streamlined instruments are more useful in order to fit multiple instruments through small incisions between ribs, the access incision (movie 3), or the only incision when the uniportal technique is being used. In a study comparing uniportal and two-port versus three-port VATS, there was no significant difference in postoperative complications between the two groups, but there was increased length of stay, chest tube duration, and drainage in the three-port group. However, there was also a much higher rate of conversion in the three-incision group; less experienced surgeons did not perform single- or dual-port procedures.

Angulation of certain instruments, such as retractors, helps keep the shaft of the instrument out of the visual field of the thoracoscope, providing the surgeon adequate retraction without encumbering the view. Angulation also reduces instrument conflict when directed at the same target through the same port (picture 4).

●Trocars – Trocars are available in different sizes that range from 3 to 15 mm in diameter (figure 13) to accommodate the instruments and the camera required to perform the procedure. If carbon dioxide insufflation is not used, 10- to 15-mm incisions for instrument passage can be made without the use of trocars, although trocars protect against soiling of the scope and lens.

●Hand ports allow passage of up to three to four instruments, or a hand, through one incision while keeping an airtight seal to maintain CO₂ insufflation. The camera can also be passed through this port if a uniportal procedure is desired.

●Grasping instruments – Various types of handles and grips are available for thoracoscopic grasping instruments. Shafts may be straight or angled, cylindrical or ovoid. Grasping instruments designed for tissue manipulation include a head and a shaft and are available in a variety of shapes and configurations. A wide-head instrument, such as a thoracoscopic Pennington clamp (triangulated eyelet) (figure 14), allows for atraumatic retraction of lung tissue. Thoracoscopic single shaft forceps, such as DeBakey forceps (figure 15), are used for more precise grasping. Some grasping instruments work better with a locking ratchet, while others that require smooth movement are better without such mechanisms. Double action mechanisms on the shaft have the advantage of opening the instruments at the tissue level rather than opening at the port site (figure 16).

●Cutting and coagulation – Thoracoscopic scissors are designed for wide blade opening at the target tissue level without widening the instrument shaft within the narrow port incision, while open Metzenbaum-type scissors can be passed through the access incision but can limit the ability to pass other instruments through the same port (figure 17).

Energy devices with different shaft lengths, tip sizes and shapes, and power sources are also available (eg, ultrasonic shears, bipolar, unipolar, argon gas, or radiofrequency) for tissue dissection and division and the sealing and ligation of vessels. Endoscopic disposable or nondisposable scissors with the ability for tip cauterization are used for delicate dissection or division. Some energy devices create smoke or steam that will obscure visualization. Saline-coupled (aka "transcollation") bipolar cautery is helpful for managing diffuse parietal and visceral pleural surface oozing [115].

The use of a suction device helps evacuate steam or smoke. If airtight seal exists due to the use of ports in all incisions to allow CO₂ insufflation or there is no extra room around any of the instruments, short bursts of suction will be needed to prevent lung inflation due to negative pressure. Opening the air vent on thoracoscopic trocars will also allow smoke and steam to vent but is more efficient if CO₂ is being insufflated. Controversy exists about whether inhalation of smoke generated from energy devices by operating room personnel is harmful with chronic exposure, and thus venting "into the air" of the operating room without a scavenging system may be discouraged. Specifically manufactured trocars are available for smoke evacuation and CO₂ circulation.

●Suturing and stapling – Thoracoscopic needle drivers with precise thumb-index finger spring-style locking mechanisms are available, but conventional ring handle suturing tools can be used through the access incision (figure 18). If extracorporeal knot tying is performed, knot pushers (figure 19), interlocking barbed sutures, and pretied knot devices can be used in addition to intracorporeal tying. Straight-shafted suture passers are helpful for placing stay sutures (figure 20). Disposable endoscopic suturing devices are available in a variety of suture sizes and materials. Devices that provide permanent or biodegradable coil-like screws are available when tacking of mesh or patch material is desired.

Thoracic endomechanical staplers are similar to those used for laparoscopic procedures. They are designed with a pistol grip leading to a cylindrical shaft to allow entrance through thoracoscopic incisions or ports. These are available for placement through a 5- to 15-mm port (figure 21). The 10- to 15-mm size is more commonly used. Manual and powered linear cutting staplers provide either two or three rows of staples on both sides of tissue divided after deployment of the stapler. Anvil extension technology has allowed staplers to be passed around tightly grouped structures more easily. Another option is a circular stapler that can be placed through the mouth or the access incision to create an anastomosis, such as during esophagectomy. Robotic linear and vascular staplers are also available.

●Suction and irrigation – Standard suction devices are available in different lengths, tip sizes, and materials (eg, metal versus plastic). Additionally, if straight-shafted suction devices are needed to fit through trocars, 5- and 10-mm battery-operated combined suction/irrigation devices are available. Straight-shaft or curved cylindrical 5-mm suction devices often become clogged or adherent to intrathoracic structures during suctioning and may not be as useful as combined suction/irrigation devices.

●Tissue removal – To prevent dissemination of infectious microbes or tumor cells, retrieval pouches are used. The strength of pouch material ranges from thick plastic for easier-to-extract specimens to durable nylon to withdraw large specimens through tight rib interspaces [116]. Alternatively, specimens can be withdrawn through specialized "wound-protector" ports that provide exposure and prevent contact with tissues passed through them.

Robotic setup — Increasingly, robotic techniques are being used for thoracic surgery, although they are still not as prevalent as with other surgical specialties such as gastrointestinal, gynecologic, and urologic surgery. As more thoracic surgeons embrace the robotic platform, the development of improved robotic equipment and instruments has decreased the limitations of anatomic positioning between the ribs, sternum, scapula, diaphragm, and spine. A feature of one robotic platform is the ability to move the camera from port to port and reassign the tasks for each robotic arm, which helps overcome the boundaries of rib spaces and the scapula.

The room arrangement must be thoughtfully considered to accommodate the need for the robotic chassis to be roughly over the patient's head while allowing access for the anesthesiologist to reach the airway and perform bronchoscopy or tube adjustments, if needed (figure 22 and picture 5). However, a smaller footprint, increased maneuverability, and more compact configuration of the arms of some models give anesthesia providers better access during chest surgery and allow use of the robot in operating rooms with less square footage.

VATS VERSUS RATS — Proponents of robotic-assisted thoracic surgery (RATS) believe that there is an easier transition from open thoracotomy to robotic surgery compared with video-assisted thoracoscopic surgery (VATS) due to the articulation capabilities of the robotic arms and instruments. The articulation allows a surgeon to use his/her hands in more familiar movement patterns to accomplish minimally invasive thoracic surgery (MITS). Other benefits of RATS may include:

●Enhanced vision with three-dimensional, high-definition, or magnified views

●Tremor reduction (filters up to 6 Hz of surgeon's hand tremors)

●Greater precision of movement

●Reduced tissue trauma (smaller-diameter instruments with more precise control and reduced levering against ribs)

●Improved reach into small crevices

●Improved agility for suturing and tying

●Availability of near-infrared fluorescence imaging to evaluate perfusion (eg, gastric conduit, pulmonary segment)

●Potential for improved outcomes (reduced hospital length of stay, time to recovery and return to normal activity, and possibly less pain)

●Potential collateral marketing advantages for the hospital

This list of features can be of particular good fit with the needs of many surgeons and their patients and of less importance to others (table 1).

There is still a steep learning curve due to the differences at many steps of the procedure from patient positioning, the robotic platform, and different instrumentation and equipment, not to mention the flow/conduct. Detractors of robotic thoracic surgery list the following detriments:

●Lack of tactile (haptic) feedback (countered by argument that visual accommodation can be achieved). Currently, VATS provides haptic feedback to the surgeon, while RATS does not [117].

●Cost of supplies, instruments, the robot system, and the service contract for the robot system.

●Longer duration of surgery (longer setup time).

●Additional training requirements/learning curve.

●Impaired verbal and nonverbal communication with surgeon.

●Need for a skilled and trusted assistant.

●Administrative issues, training, and credentialing of nurses and technician.

●Potential for mechanical or electrical malfunction.

●Scheduling conflicts if the robot is in high demand and used by multiple subspecialty services.

General issues and areas of controversy — As authors of this topic, we are proponents of less invasive surgery. However, it is important to acknowledge that there is a broad range of techniques and technologies, resulting in considerable variability in approaches between institutions and surgeons. Nevertheless, there is uniform agreement among surgeons that the core principles of thoughtful patient selection, adequate exposure, dissection, traction and countertraction, optimal perioperative care, and oncologic validity should not be compromised. Following these principles, surgeons adopt new tools and techniques to complement and/or augment their past experience, optimize local resources (such as assistant availability), and try to increase case density to justify adopting disruptive or more expensive technologies [118,119].

As an example, there is wide variation among individuals in the ability to process two-dimensional images into the three-dimensional spatial awareness that is needed to perform thoracoscopic surgery. Some surgeons are very reliant on stereoscopic vision, while others are relatively stereoblind or become that way as they age [120]. As a result, robotic surgery became popular, partly because of its three-dimensional optics, but also because of its ability to allow skilled surgeons to translate their open surgical movements to the confined space and to control more of the operation by rapidly resetting retraction forces in one of the ports [121]. Conversely, other surgeons prefer different optics, less articulated laparoscopic/thoracoscopic instruments, and high-functioning assistants to maximize their effectiveness.

Considerable investment is made by an institution and the individual surgeon to transition from open surgery to safe minimally invasive surgery. Thus, it is understandable why there are spirited discussions among stakeholders on what is the best approach. Debated approach options range from traditional open, two- to four-port VATS (with or without a larger access incision); patient position, such as supine, partial decubitus, full lateral decubitus, or prone; the optimal sequence of dividing structures (like fissures, vessels, and bronchi); uniportal surgery (subxiphoid versus transthoracic); robotic surgery (including robotic uniportal); microlobectomy; and others.

Rather than wading into such debates, it is better to focus on the fact that all these technologies fit into a broader system of perioperative care that affects the outcomes of these less invasive procedures. Thus, a limited thoracotomy with a good enhanced recovery pathway might provide similar hospital outcomes to less invasive procedures, including robotic-assisted surgery, particularly if there is preemptive management or prevention of pleural inflammation and chest wall trauma. A study from one institution challenged the benefits of minimally invasive thoracic surgery [118]. The discussants in that paper noted difficulties interpreting the data when considering bias caused by conversions and case selection. Regardless, the evidence of better perioperative outcomes with less invasive surgery is increased for special populations such as older adult or frail patient groups [1].

Since research on the various minimally invasive approaches often does not tabulate the corresponding open cases, it is hard to know about selection bias. Some institutions perform over 90 percent of minimally invasive anatomic pulmonary resections because they attempt more advanced central tumors that tend to have higher risks and conversion rates. There is also debate regarding the oncologic validity of minimally invasive approaches because of reports of less cancer upstaging in VATS groups [59]. However, this may be from a preference for open surgery for central tumors. Oncologic efficacy such as adequate lymph node assessment seems to be more a function of the institutional standards and surgeon practice rather than strictly based upon the approach [122].

Of course, randomized trial data would be ideal, but studies assorting different levels of surgical invasiveness have not been popular to patients or investigators. It took a consortium of very high-volume hospitals in China to complete accrual to a modest VATS versus axillary thoracotomy trial [63]. There are broad trends in surgery (and medicine, in general) to progress by offering targeted and less invasive means to increase patient tolerability and satisfaction. Thus, it is unlikely that minimally invasive thoracic surgery growth will slow until there is a signal in clinical trials and database queries that such approaches are inferior. Such a warning signal has not emerged, and therefore, research resources may be better applied to other contemporary concerns, like the optimal use of competing ablative therapies, such as stereotactic radiation. Also, there have been an increasing number of reports of equivalent or even more favorable outcomes for minimally invasive resections in cases where the technique was formerly regarded as contraindicated, such as in those with large, central tumors requiring sleeve resection, or following induction therapies [123-127].

Outcome comparison for pulmonary resection — Outcome data comparing RATS with VATS pulmonary resection are sparse and challenging to interpret [128]. No large prospective randomized series are available. Comparisons are hampered by the fact that technical aspects of both RATS and VATS pulmonary resection are not standardized (including port positions, utility port incision size, instruments used) and are seldom specified. It is unclear where on the learning curve surgeons exist for different studies, and selection bias as well as publication bias are difficult to exclude. These issues are discussed above. (See 'General issues and areas of controversy' above.)

The limited data thus far regarding thoracic surgery indicate that clinically important outcomes are similar for RATS and VATS at high-functioning centers [64,129-135]. Definitive statements comparing RATS pulmonary resection with VATS await prospective randomized trials with greater control of technical variables, patient selection, and surgical experience levels. Since both are minimally invasive, it may be easier to conduct these trials compared with those that failed to have patients accept open operations when less invasive ones were available. The following studies represent typical findings in retrospective comparisons for various pulmonary resections.

●One study that compared 2498 robotic lobectomies with 37,595 VATS lobectomies performed between 2008 and 2011 found higher rates of intraoperative injury and bleeding in the RATS group [131]; however, morbidity and mortality for RATS versus VATS lobectomy were similar in another study [132]. There was no evidence that long-term oncologic outcome from RATS pulmonary resection for cancer is different from VATS [132].

●In a comparison of VATS with RATS for anatomic segmentectomy, morbidity and mortality were similar, but RATS had a longer surgical (console) times and a tendency for shorter hospital stays [133].

●In a comparison of RATS versus VATS lobectomies and wedge resections, RATS had higher hospital costs and longer operating times without any differences in adverse events [134].

●In a case-control analysis of 46 robotic resections (40 lobectomies, 6 anatomic segmentectomies) and 34 VATS resections (27 lobectomies, 7 segmentectomies), there was no difference between operative time, length of hospital stay, major or minor morbidity, or nodal sampling completeness [135]. A shorter duration of narcotic use and faster return to usual activities/work was noted for the robotics group, which may have been related to better preoperative performance status scores in the robotic group.

A propensity matched study of open, VATS, and RATS lobectomy evaluating outcomes showed no significant difference in complication rates [136,137]. There were more lymph node stations sampled using a robotic approach compared with open surgery or VATS, but this did not translate into a difference in disease-free or overall survival. How nodal upstaging translates to overall survival was questioned by another registry study [138]. In another propensity matched study that compared only VATS and robotic lobectomy, there was no difference in number of lymph nodes or number of lymph node stations, blood loss, chest tube duration, complication rate, or length of stay. However, robotic lobectomy was calculated to be approximately $4000 more per surgery and with a longer operative time by 25 minutes [136].

GENERAL PRINCIPLES

Patient positioning — Patient positioning is generally in the lateral decubitus position with the operative side up, though positioning is influenced by the surgical indication (eg, supine for some mediastinal operations, prone positioning preferred by some surgeons for thoracic portion of esophagectomy). (See "Patient positioning for surgery and anesthesia in adults".)

For the lateral decubitus position, padding of pressure points and adequate support of the arm on the operative side are required (figure 23). The arm on the operative side is supported by padded armrests that clamp to the operating table. Although stacked pillows can be used for arm support, regular-sized pillows may interfere with the anterior incision. "Beanbags" that stiffen to conform to the chest and hold the patient by vacuum, laminectomy rolls, padded bolsters or bed attachments, and specially formed cushions stabilize the patient in the decubitus position. The patient's waist should be centered at the level of the break in the operative table and supported by a "kidney rest." When the table is flexed, the intercostal space is widened and the profile of the hip is lowered to facilitate the positioning and movement of surgical instruments.

The supine or prone positions are alternatives to the lateral decubitus position. Prone positioning is typically selected for posterior mediastinal procedures and requires special padding of the face and eyes and extra secure fastening of the endotracheal tube.

Incisions — Optimal port placement allows a greater range of operative field in the pleural or mediastinal space and helps with ergonomics. Surgeons need to be in a comfortable, relaxed position during procedures to facilitate successful and safe completion of the surgery, decreased risk of repetitive movement injury, and optimal visualization. The three-dimensional relationship of the operative field, ribs, scapula, diaphragm, and mediastinal structures are considered when making the incisions (figure 24). In general, if ports are placed in triangular positions on the skin surface, the operation will proceed without the instruments blocking each other within the chest.

●Video-assisted thoracoscopic surgery (VATS) uses a primary access or utility incision that ranges from 2.5 to 8 cm in length and allows manipulation of multiple traditional thoracotomy or thoracoscopic instruments through a single incision at the same time, though with the possibility of using additional 0.3- to 1.5-cm incisions. The term "uniportal" refers to the use of VATS through only one utility incision. Uniportal access is being adopted by increasing number of surgeons. Surgeons are also moving the location to the transaxillary and subxiphoid regions (picture 6) [139-141].

●The incisions for totally thoracoscopic surgery are between 0.5 and 2 cm. Some thoracoscopes have a working port through which biopsies or fluid aspiration can be performed (figure 5). Other thoracoscopes, termed "needlescopes," are 3 to 5 mm in diameter, facilitating passage of instruments through the same incision without increasing the length of the incision to that of an access incision [142]. For more complex procedures, other incisions can be added. The position for additional incisions is best determined under direct vision inside the chest to avoid adhesions or structures such as the heart and diaphragm and to facilitate passage and prevent crowding of instruments in the chest.

●The incisions of robotic-assisted thoracoscopic surgery (RATS) are positioned to allow adequate space for the movement of the robotic arms. An assistant incision allows suctioning, additional retraction, passage of gauze rolls, hemostatic agents and clips, and specimen extraction. The assistant port is also used as an extraction site and has been positioned in variable locations, including subxiphoid and transdiaphragmatic positions. Some robotic surgeons prefer to use the same port placement for all surgeries in the chest, while others adapt port positions and number of arms utilized (three versus four) depending upon the anatomic structure being operated upon.

Insufflation — Some procedures in the chest and mediastinum may be aided with low pressure CO₂ insufflation. Situations where CO₂ insufflation is helpful are when there is significant emphysema with suboptimal lung deflation, anterior mediastinal procedures, relatively elevated unilateral hemidiaphragm, and inability or desire not to attain selective lung ventilation. If CO₂ insufflation is used, different trocars with airtight seals will be necessary. The trocars used for robotic surgery allow for CO₂ insufflation. Care is taken to reduce the risk of CO₂ embolism through open lung parenchyma. Low pressure insufflation is used to decrease hypotension from mediastinal shifting. (See 'Contraindications' above.)

MITS PROCEDURES — All procedures traditionally performed as open procedures can be performed using video assistance. Common video-assisted thoracoscopic surgical (VATS) procedures include biopsy, decortication, pericardial window, excision of mediastinal masses, esophageal myotomy, esophageal diverticulectomy, esophageal resection, chest wall resection, and pulmonary resection. Following clinically indicated VATS surgery, patients have equivalent or better outcomes compared with open surgery. Robotic-assisted thoracoscopic surgery (RATS) can be used to perform all of the procedures currently performed using VATS; it is not yet as widely used although volume is increasing, and there are less outcomes data [59-62,143]. However, early results from large databases seem to be equivalent [12]. (See 'Outcome comparison for pulmonary resection' above.)

As technology continues to improve and surgeon experience increases, more complex and technically challenging procedures are being performed. Some of these include lung resection with en bloc chest wall resection, first rib excision, sleeve lobectomy, pneumonectomy, bronchoplasty, pulmonary angioplasty, radical pleurectomy, and tracheoplasty. Continued outcomes assessment is needed to ensure that VATS provides equivalent or improved outcomes compared with traditional open surgical methods.

Mediastinal lymph node biopsy — Biopsy of mediastinal lymphadenopathy for diagnosis can be performed as the primary thoracoscopic procedure or at the time of planned lung or esophageal resection. Lymph node sampling for diagnostic purposes or full dissection during lung or esophageal resection for cancer yield comparable numbers of nodes for VATS compared with open procedures. While some large database studies suggested that there may be inadequate numbers of nodes retrieved by VATS [144], this was probably a statistical aberration caused by the avoidance of resection of central tumors that are lymphatic-rich. Later studies show uniform recovery of nodes in series as central tumors resected by minimally invasive thoracic surgery (MITS) [145,146]. Sampling of lymph nodes for restaging can be more challenging if there are fibrotic or inflammatory changes related to chemotherapy or radiation therapy. Complete mediastinal lymphadenectomy can be performed via VATS technique, but care must be taken to avoid injury to the surrounding mediastinal structures (figure 25A-B) [86,147-150]. (See "Surgical evaluation of mediastinal lymphadenopathy".)

The approach to various lymph node groups is as follows:

●The right paratracheal, subcarinal, periesophageal, and inferior pulmonary ligament lymph nodes are easily biopsied via right thoracoscopy.

●Biopsy of the left paratracheal and subcarinal lymph nodes by the left thoracoscopy can be challenging. When biopsying the left paratracheal lymph nodes, care must be taken not to damage the aorta, arch vessels, left recurrent laryngeal nerve, or left phrenic nerve since mobilization of the aortic arch is required for access. The subcarinal lymph nodes can be buried deep in the field when being accessed from the left side, and injury to the airway, esophagus, pulmonary artery, aorta, or vagus nerve can occur. A Valsalva maneuver by the anesthesiologist can aid in exposure of the subcarinal lymph nodes from the left.

●The aortopulmonary window, anterior aortic, periesophageal, and inferior pulmonary ligament lymph nodes are easily accessed (figure 25A); however, care must be taken to avoid the left recurrent laryngeal nerve with this approach.

Excision of mediastinal masses — Many masses located in the anterior, middle, or posterior mediastinum can be approached using a minimally invasive approach. (See "Approach to the adult patient with a mediastinal mass".)

●In the anterior mediastinum, thymectomy is performed for symptomatic relief of myasthenia gravis or for thymic mass, of which the great majority will be thymoma [151,152]. VATS thymoma (picture 7) resection requires careful patient selection [153]. Complete excision of the mass with clear margins is imperative as it can recur if margins are positive. VATS thymectomy has been performed from either the right or left side in slight decubitus or complete decubitus positions [154]. Several series comparing VATS with other approaches have promising results for long-term relief of myasthenic symptoms or low recurrence rates of thymoma [153-155]. In retrospective reviews, there were no significant differences in overall survival or disease-free survival between open and VATS thymectomy for early-stage thymoma [156,157]. (See "Role of thymectomy in patients with myasthenia gravis" and "Thymectomy".)

RATS for thymectomy is appealing for many surgeons because of the advantages of the robotic platform for performing dissection in a tight space. Three-dimensional optics and gas insufflation appear useful as well. Thus far, short- and mid-term data appear favorable [152,158,159]. In a systematic review, no significant differences were seen for conversion rates or length of stay, but RATS had longer operative time by approximately 20 minutes [159]. There were no operative deaths in either group.

●In the middle mediastinum, MITS excision of masses (bronchogenic cyst, pericardial cyst) is becoming more routine [160]. Although intact resection is usually the goal, if a cyst is densely adherent to trachea, bronchus, or esophagus, a small portion of cyst wall may need to be left behind. If left behind, surgeons generally attempt to ablate residual mucosa. Aspiration of a portion of the cyst contents during excision can be helpful for improved vision of underlying structures and allow cyst manipulation without rupture [161-163]. Sometimes surrounding inflammation from prior infection increases the technical challenge of removing bronchogenic or esophageal duplication cysts. Pericardial cysts may fluctuate in size, and it is unusual for them to become inflamed or infected. While easily resected, pericardial cysts generally are observed if asymptomatic.

●In the posterior mediastinum, excision of typically benign neurogenic tumors can be performed by MITS. Complete excision of malignant neurogenic tumors may not be feasible using MITS (or open technique) if the mass is adherent to structures such as the aorta, trachea, or esophagus. Some neurogenic tumors will have a dumbbell shape with one portion extending into the spinal canal. A neurosurgeon may need to divide the involved nerve root using a posterior approach, before attempting a MITS approach to the tumor, which can often be performed as a single-stage operation [160,164,165].

Chest drainage/pleurectomy — Drainage of hemothorax, empyema, or malignant pleural effusion and mechanical or chemical pleurodesis are some of the more basic problems that can be approached using thoracoscopy. Pleurodesis or pleurectomy (ie, decortication) can be indicated for recurrent pneumothorax or malignant pleural effusion. Experience and judgment, appearance of the radiologic studies, and the patient's clinical course all contribute to the decision of whether to perform these using thoracoscopy, robotically, or with open techniques.

VATS for pleural problems has equivalent success with regard to drainage of hemothorax and empyema with a faster recovery and decreased pain [68,69]. The main determinant of success for MITS decortication is performing the surgery during the exudative or fibropurulent stages as opposed to the organized fibrotic stage [68-70]. Complete circumferential excision of thick or laminar peel on the visceral and parietal pleura is difficult due to the tough (picture 8), slippery nature and inability to adequately grasp the peel with available thoracoscopic instrumentation. Some surgeons prefer to perform pleurectomy with the lung under positive pressure.

Types of pulmonary resection — An overview of pulmonary resection is provided separately. Issues pertaining to a minimally invasive approach are reviewed briefly below. (See "Overview of pulmonary resection".)

Nonanatomic wedge resection — Pulmonary wedge resections are performed for both diagnostic and therapeutic reasons. Lung wedge resections are nonanatomic and akin to removing a pie slice with the portion of excised lung encompassing a lesion or area of disease/abnormality (figure 26). The area of lung to be excised must be mobile, and resections that include a branch of pulmonary artery or draining vein will first require proximal vascular control to prevent bleeding with division of the lung tissue. If the lesion is small or not visible on the surface of the lung, instruments or a finger can be inserted into the chest cavity to palpate the lung and localize the lesion (movie 4). Landmarks can also be used to estimate where the lesion is located, but some interpolation is necessary as radiologic imaging is usually performed with the lung fully inflated, while surgery is performed on the deflated lung. If a nodule is expected to be hard to find, it can be localized by a variety of methods including computed tomography (CT)-guided methods, navigational bronchoscopy with dye marking, radionucleotide, and even real-time on-table imaging [166-168]. As with open thoracotomy, surgical staplers ("endostaplers") provide fast and reliable hemostasis of the raw edge of resected lung and minimize air leak. Sometimes, long "compression" clamps are needed to squeeze the lung to allow passage of the stapler to avoid the jaws injuring the lung tissue. Powered staplers are advertised to provide more stapler stability and less tissue movement than manual staplers and thus improve hemostasis and decrease air leak. However, few studies of VATS using powered staplers have been reported [169].

Anatomic lung resection — Anatomic lung resections can include segments of lung up to a whole lung (pneumonectomy). Anatomic lung resections are technically challenging and require dissection of the vascular and bronchial structures supplying the portion of lung being removed (picture 9 and movie 5 and movie 6) [147,170].

The most common reason for performing anatomic lung resection in the United States is for early-stage lung cancer, and the most common procedure for lung cancer is lobectomy for curative intent. Lymph node dissection is included for staging purposes; however, it is unclear whether removing involved lymph nodes has a therapeutic benefit beyond more accurate staging. The ability to remove a comparable number of lymph nodes from the pertinent mediastinal and hilar regions during MITS lung resection for cancer has been demonstrated [59-62,149,171].

The types of complications of MITS lung resection are similar to those of open surgery (eg, bleeding, bronchial leak or damage); however, seeding of cancer at port sites is specific to a thoracoscopic approach and has been reported as 1.1 to 7.0 percent, 0.2 to 0.4 percent, and 0.3 to 0.6 percent in various reports [101,172,173]. The authors are not aware of any reports of port site recurrence from RATS lobectomy. Conversion rates from VATS and RATS to thoracotomy for anatomic resection ranges between 1.6 and 21 percent and 3.3 and 10.3 percent, respectively. Reasons for conversion include bleeding, difficult anatomy, adhesions, challenging or inadequate lymph node dissection, and increased procedure complexity for oncologic reasons [66,101,172,173].

Some studies have reported that anatomic lung resections using VATS result in decreased chest tube duration, decreased complication rates, and similar, if not improved, survival rates compared with traditional open incisions [4,101,174-177]. There are also reports of a decreased inflammatory response with VATS lung resection compared with thoracotomy or sternotomy as evidenced by decreased levels of interleukin-6, interleukin-8, and interleukin-10 [170,178,179]. It is speculated that some of the improved survival rates that are reported with VATS are related to better patient selection, better adherence to National Comprehensive Cancer Network (NCCN) guidelines, or more consistent lymph node sampling or dissection by specialty thoracic surgeons [175,180-184]. However, the proportion of procedures performed by thoracic surgeons versus other surgeons has not been typically reported. Intraoperative oncologic staging and outcomes for lung cancer resection vary by surgeon specialty [185]. Studies using administrative and quality improvement databases show decreased perioperative mortality when lung cancer resection is performed by noncardiac thoracic surgeons compared with general surgeons or primarily cardiac surgeons. Five-year survival rates are improved and costs are lower for higher-volume surgeons in practice for 5 to 15 years [182,186,187]. In the VIOLET (VIdeo-assisted thoracoscopic lobectomy versus conventional Open LobEcTomy for lung cancer) trial, 503 participants were randomly assigned to VATS or open lobectomy [65]. The incidence of serious adverse events after discharge was lower for VATS compared with open surgery (30.7 versus 37.8 percent, risk ratio 0.81, 95% CI 0.66-1.00). There was no difference in R0 resection, upstaging, or time to adjuvant therapy. At 52 weeks, cancer progression-free survival and overall survival were similar, but the study was not powered to detect survival difference [66].

Excision of blebs/bullae — Resection of pulmonary blebs and bullae (figure 27) may be indicated to prevent spontaneous pneumothorax from rupture or for ongoing air leak following thoracostomy tube placement (picture 10) [188]. (See "Pneumothorax in adults: Epidemiology and etiology" and "Bullectomy for giant bullae".)

Bullae, which are thinned areas of lung parenchyma, are typically >1 cm in diameter with wall thickness <1 mm and typically occur from parenchymal destruction such as that caused by emphysema (picture 11). Large bullae can occupy up to one-half of the volume of the pleural cavity, leading to contralateral lung compression. A bleb is smaller than 1 cm in diameter and typically subpleural and located more cephalad. Blebs may occur from alveolar disruption in patients with otherwise relatively normal parenchyma.

When intervention is indicated, the margins of resection should be performed in the more normal (less emphysematous) lung parenchyma, which is more likely to heal faster. As with open surgery, prolonged air leak can occur related to poor sealing of thin lung parenchyma at the staple line margin or from lung lacerations that may occur from taking down adhesions. Methods for decreasing leaks from staple lines include the use of buttressing materials made of synthetic copolymer or collagen matrix that are attached to endoscopic staplers prior to firing across the lung parenchyma, or the application of biological glue over the staple line. Pleurodesis is also used to decrease air leak after bullectomy [189-191].

One potential risk of a thoracoscopic approach is not finding a leaking bleb due to the inability to see all portions of the lung due to prevention of camera access to an area of the chest if there are adhesions or scarred areas, or from a loss of viewing domain with the lung inflated.

Lung volume reduction surgery — Lung volume reduction surgery (LVRS) involves removing the apical portions of one or both lungs to improve overall respiratory function in patients with significant upper lobar emphysema. LVRS, which can be performed via sternotomy or bilateral thoracotomy, can also be performed by bilateral VATS. Because VATS is less invasive, there is a faster recovery time, decreased cost, decreased length of stay, and decreased rate of complication found [192-194]. There is no difference in functional results or mortality when comparing VATS with open methods of LVRS. (See "Lung volume reduction surgery in COPD".)

Other procedures — Other procedures that have been reported using a VATS approach include pericardial window, thoracic duct ligation, and sympathectomy.

Pericardial window — MITS pericardial window is performed in the lateral decubitus position with single-lung ventilation or CO₂ insufflation for diagnostic and therapeutic indications (eg, pericardial effusion). MITS pericardial window accomplished from the left side provides increased surface area of pericardium, resulting in larger pericardial window compared with a right-sided approach (figure 28). Nevertheless, an approach from the right is useful if a simultaneous right-sided pleural effusion is present or there is a prior pleurodesis or adhesions on the left [195,196]. (See "Cardiac tamponade".)

Thoracic duct ligation — Thoracic duct ligation is performed to manage complications of thoracic duct injury leading to chylothorax (picture 12). Intraoperative enteral lipid administration may aid the identification of iatrogenic duct injuries [197,198].

Thoracic duct ligation can be achieved satisfactorily using MITS, and the field of view may be better compared with open surgery. A short segment of the duct in the inferior chest, just between the azygos vein and aorta, is exposed by careful dissection from a right MITS approach. Multiple sutures or clips are placed for ligation.

Although this same procedure can be performed after an esophagectomy, which is one of the most common iatrogenic reasons for chylothorax, the level of difficulty is increased due to the presence of the neoesophagus, which needs to be retracted out of the way to gain access to the thoracic duct.

Sympathectomy — Division, clipping, or thermal ablation of the sympathetic chain (picture 13) at the appropriate level have been accomplished thoracoscopically with minimal intraoperative complications and immediate symptom relief [199,200]. However, compensatory hyperhidrosis below the level of the sympathectomy can be disabling. Accordingly, temporary treatment with thoracoscopic local anesthetic blockade or reversal of the operation by clip removal may be indicated for certain patients [201]. (See "Primary focal hyperhidrosis".)

POSTOPERATIVE CARE AND FOLLOW-UP — Many of the same guidelines/clinical pathways used for thoracotomy or sternotomy are used after minimally invasive thoracic surgery (MITS). Improved recovery and shorter length of stay have been reported for MITS compared with patients who have had a thoracotomy with or without rib division [4,5,174,202]. Enhanced recovery after surgery (ERAS) pathways have reduced length of stay and complication rates following open thoracotomy, but implementation has not appeared to alter outcomes following MITS, likely since many elements of ERAS may already be included in the care of these patients [203]. (See 'General issues and areas of controversy' above.)

Postoperative care, including chest tube management following pulmonary resection, is reviewed elsewhere. It should be noted that the expanding use of digital chest tube collection systems may be useful to help monitor and predict safe cessation of pleural drainage. Some systems are being developed to detect metabolically generated CO₂ or inhaled compounds to sort out difficult cases in which a small or intermittent parenchymal leak are hard to distinguish from system seal failures [204,205]. (See "Thoracostomy tubes and catheters: Management and removal", section on 'Drainage systems' and "Overview of pulmonary resection", section on 'Chest tube placement and management'.)

COMPLICATIONS — In general, complications related to minimally invasive thoracic procedures are similar to those of the open surgical approach; however, some complications can be more significant. These include the potential for bleeding, and complications related to technical aspects of the surgery. A comparison of outcomes is provided separately. (See "Overview of pulmonary resection", section on 'Open versus minimally invasive lung resection'.)

Bleeding may obscure the view from soiling of the scope, and bleeding from major vessels (eg, bleeding from a pulmonary artery, aorta) is of great concern and may require conversion to an open procedure for rapid hemostasis. Bleeding rates in video-assisted thoracoscopic surgery (VATS) series range from 0.4 to 2 percent [206]. A retrospective review that included 1304 patients reported a 2.6 percent rate of major vascular injury during robotic lobectomy [104]. There have been no cases in the literature of intraoperative death due to exsanguination during minimally invasive thoracic surgical (MITS) lung resection, but such events are almost certainly underreported.

Conversion to thoracotomy may be required due to bleeding or other reasons such as difficult anatomy, central tumor location with need for more complex vascular or bronchiolar reconstruction, or the inability to attain or tolerate selective lung ventilation. Reported conversion rates range from 1.6 to 21 percent [104,147,206,207].

Injury to the diaphragm, liver, or spleen may occur, particularly during placement of the primary port, which is often performed blindly without the benefit of the thoracoscope. Some methods to avoid this complication include careful imaging reviews to identify anatomic variations; entering the pleura under direct vision when creating the first port or starting with cephalad ports and viewing caudad to optimize placement of inferior ports; considering rises of diaphragm from atelectasis caused by single-lung ventilation; obesity; and, finally, placement of a port that allows camera viewing at its tip like that common in laparoscopic surgery. Diaphragm injuries are usually not serious though they require repair, whereas injuries to the liver or spleen can cause significant hemorrhage [207,208].

Port site recurrence has been reported following resection of pulmonary and esophageal tumors [84,101,172,173].

Compression and injury to the intercostal nerves can occur with thoracoscopy. The discomfort usually improves, but in rare instances, chronic pain persists at thoracoscopic port sites. Intercostal nerve injury during robotic-assisted thoracic surgery (RATS) may be less compared with VATS because of the fixed point of the robotic ports; however, both are likely operator dependent and affected by choice of intercostal space and degree of torque generated at extreme angles of retraction.

SUMMARY AND RECOMMENDATIONS

●Diagnostic and therapeutic procedures can be performed using a minimally invasive thoracic surgery (MITS), either video- or robotic-assisted thoracoscopic surgery (VATS/RATS). These include intrathoracic biopsies (eg, pulmonary tissue, mediastinal nodes), resections (eg, pulmonary, esophageal), and chest wall resection or reconstruction (eg, pectus excavatum). (See 'Thoracoscopic surgery' above and 'Indications' above.)

●There are purported benefits to performing some thoracic operations using MITS, and in skilled hands the completeness of the operation is likely equivalent to the open approach in many instances. VATS and RATS have their own sets of relative advantages and disadvantages. The technology continues to improve, and the techniques continue to evolve. (See 'Indications' above and 'VATS versus RATS' above.)

●Pulmonary function tests are performed to identify patients who would not tolerate selective pulmonary ventilation required to perform MITS. (See 'Patient selection' above.)

●Much of the equipment and instrumentation is identical to that used during thoracotomy, thoracoscopy, and laparoscopy, although refinements (eg, angulation) have been made to facilitate performing complex MITS procedures. (See 'Equipment' above.)

●Acquisition of MITS skills requires frequent repetition and is hindered if case volume is low. Guidelines vary on the number of cases that should be performed to demonstrate proficiency. The individual institution or hospital system generally sets their own standard for credentialing and privileging for these procedures, specifying demonstration of training, mentoring of initial cases, and a minimum annual case volume. (See 'Learning curve and credentialing' above.)

●The benefits of MITS appear to outweigh the disadvantages thus far, and increased experience and advancement of technology will help clarify which disease processes and procedures are improved by use of MITS. Some randomized trials and observational studies suggest decreased perioperative morbidity, length of stay, pain, and recovery time following MITS compared with those of open surgery for lung resection, which is currently the most commonly performed MITS procedure. (See 'Types of pulmonary resection' above.)

●Complications after MITS are similar to those of open thoracic surgery, but some complications are unique to MITS. These include diaphragmatic or organ laceration from port placement and port-site tumor seeding, which can often be mitigated with preventive measures. Awareness of the unique morbidities associated with MITS may help alleviate the incidence as more experience is gained. (See 'Complications' above.)