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Modern thoracic approaches: minimally invasive thoracic surgery

M. Blair Marshall

INTRODUCTION

Chapters written on thoracic incisions have historically dealt with the traditional approaches used in the practice of thoracic surgery. These are standard incisions that provide exposure to the common thoracic pathologies. These have changed relatively little in the previous decades and have been written about in previous versions of this text and oth ers; I will not review these approaches here but refer you to the previous versions of this text.

Modern approaches, strategies for less invasive means of managing thoracic pathology have continued to grow over the past two decades, and these ongoing developments will be addressed by this chapter. These will be broken down by anatomic location: pulmonary resections; wedge excision and hilar dissections; and mediastinal approaches, anterior and posterior, including the intraoperative strategies to facili tate working through these smaller incisions. The reasoning for this is that given the limited access through small inci sions, operative planning for these less invasive approaches must take into account the location of the pathology; hin drances to access; hindrances for instrumentation; strategies for resection; and reconstruction, when needed. When com pared with an open approach, a minimally invasive approach itself may be considered a hindrance; however, the magnified view, ability to use angled cameras to change perspective, as well as the markedly decreased pain and recovery time com monly associated with these approaches more than justify their use.

THORACOSCOPY VERSUS LAPAROSCOPY

Although those who pioneered the field of minimally invasive thoracic surgery did not have general surgical expe rience in minimally invasive surgery, that is not true of today’s trainees. In transitioning from minimally invasive intra-abdominal surgery to thoracic surgery, there are some important differences.

Minimally invasive approaches are typically taught with the baseball diamond concept in mind (see Figure 1.1). This is where the camera typically resides at the base of the diamond and the surgeon operates with two instruments on either side, through ports placed at points B and D. The pathology is typically located at point C. This approach is kept in mind when planning thoracoscopic and laparoscopic procedures; however, important adjustments are made due to location within the chest, limitations of the bony fixed chest wall, and span of operative pathology. For example, complete intrathoracic dissection of the esophagus requires much more movement than a laparoscopic cholecystectomy where the operative field is fairly small. Also, unlike most abdominal approaches, as the complexity of the intratho racic procedures performed increases, we add extra ports and frequently move the camera from one area to another to maximize visualization. Lastly, as many thoracic proce dures are performed with the patient in the lateral decubitus position, visuospatial challenges are created when working under camera guidance, in particular when surgeons are on opposite sides of the table.

INSTRUMENTS AND ACCESSORIES

Instruments

Given the limits of the size of the incisions currently being used for video-assisted thoracoscopic surgery (VATS), tra ditional open instruments have limited functionality within these small incisions. Traditional instruments need to be oriented along the intercostal space to function. Those who use them in these situations quickly learn of their limitations as the sizes of their incisions become progressively smaller. Additional instruments have been developed specifically for VATS. These differ from laparoscopic instruments, as early VATS procedures often did not use insufflation of carbon dioxide (CO₂), thus maintenance of an airtight seal was not required. VATS instruments are similar to open instruments with alterations to the hinge points to facilitate use between the intercostal spaces (see Figure 1.2). In addition, they are available with a variety of curvatures allowing access to all of the spaces of the chest, in particular to the chest wall. Access to certain areas of the parietal pleura and chest wall is limited with the use of straight laparoscopic instruments. VATS-specific instruments are provided through a variety of vendors and some are more cumbersome than others—one should try out these instruments prior to committing to purchasing.

After many years of performing minimally invasive tho racic surgery, we have incorporated standard laparoscopic instruments into all of our procedures, having found they provide a number of advantages. Specifically, their hinge point is always at the end closest to the operator’s hand when the instrument is within the thoracic cavity; they work through the 5 mm ports; and they come in a variety of lengths, from 20 to 45 cm. Additionally, most hospitals already have several sets of these instruments, so they do not require an additional capital purchase. When working with both hands from the posterior and anterior aspect of the chest, or for hilar work when the patient is in the lateral decubitus position, we have found the standard laparoscopic length does not work particularly well. However, we have found pediatric laparoscopic instruments to be of use when working at the hilum, as that length is ideally suited for most adult patients (see Figure 1.3 a and b).

When working in the anterior or posterior mediasti num, the length of the standard laparoscopic instruments works well. In particular, for video-assisted thymectomy or minimally invasive esophagectomy, the length of these instruments tends to be advantageous allowing one to work superiorly to dissect the cervical horns of the thymus gland or, for an esophageal resection, to dissect the entire length of the intrathoracic esophagus, from diaphragm to thoracic outlet.

Ports

For port access, we use a metal trocar with a collar we have modified so that it does not interfere with the trocar angu larity (see mediastinal resections below). When using CO₂ insufflation, one must use either metal ports with an adapter for insufflation, as with the3 mm ports (see Figure 1.3a and b), or disposable laparoscopic trocars. Although the latter add to the expense of the procedure, they can be par ticularly useful in the obese patient where metal trocars are often too short to completely traverse the chest wall. For the utility incision, which is larger than a typical port, we use a soft-tissue retractor such as the Alexis wound protector (Applied Medical Resources Corporation, Rancho Santa Margarita, California, United States). Although purists argue that this is not “true” VATS, and may not be necessary in the thin older individual, it is particularly useful in larger patients.

Camera

We use a 30-degree 5 mm endoscope with a high-definition camera, as the current optics are so good we have found lit tle use for the 10 mm camera. The 30-degree angle allows for improved visualization through rotation of the lens. Today, additional endoscopes are available that strategically address challenges associated with the camera view, such as the EndoEYE (Olympus New Zealand Ltd., Auckland, New Zealand) and three-dimensional viewing VITOM 3D Karl Storz GmbH and Co. KG, Tuttlingen, Germany). In our experience, although conceptually attractive, the location of the articulation joint for the EndoEYE endoscope can interfere with the operative procedure, so we have not yet found this technology useful. This is particularly true for the smaller patient. As well, operation of this initial prototype is not intuitive. Future improvements will probably address these limitations.

CO₂ insufflation

The use of CO₂ insufflation in chest surgery has become progressively more popular. We use it frequently and find that it facilitates a number of maneuvers when working within the confines of the chest. In contrast to an intra abdominal procedure, where the insufflated pressure limit is set at 15 mmHg, for intrathoracic procedures, we go no higher than 10 mmHg, as any higher pressure often results in hypotension due to restriction of venous return to the right atrium.

When performing thoracic surgery without single lung ventilation, CO₂ insufflation creates a large enough pneu mothorax to provide a working space. This is particularly useful for bilateral VATS sympathectomy, where the patient is positioned supine.

When performing thymectomy, the addition of insuf flation remarkably improves visualization of the anterior mediastinum. When working on the left side, the intratho racic pressure obtained with insufflation is enough to push the heart toward the right to create sufficient working space. As well, it allows visibility of the inferior aspect of the neck beneath the heads of the clavicles (see Figure 1.4). With the use of CO₂ insufflation, we perform VATS thymectomy with out lung isolation but feel that, for those without experience, using CO₂ in the chest it is more safely performed with lung isolation.

Insufflation of CO₂ during VATS diaphragmatic plication allows for increased intrathoracic space, as the CO₂ displaces the diaphragm inferiorly allowing for better visualization.

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