Thoracoscopic procedures for intrathoracic and pulmonary diseases
Abstract
Since Jacobaeus performed the first thoracoscopy to explore pleural space and mechanically broke pleural adhesions to facilitate the collapse therapy for pulmonary tuberculosis in 1910, numerous thoracic surgeons have been attempting this technique as a means of accomplishing many intrathoracic procedures previously done through open thoracotomy. As the refinement of video technology has advanced, thoracoscopic surgery has played a very important role in thoracic surgery especially since the early 1990s. Because the advantages of video-assisted thoracoscopic surgery for patients include low post-thoracotomy-related morbidity, cosmetic considerations, low pain, earlier post-operative mobilization, and a shorter operation time in some indications, surgeons have been demonstrating its increasing utility in the diagnosis and treatment of the pleura, lung, mediastinum, great vessels, pericardium, and oesophagus. The most common application of the thoracoscopic approach still remains in the management of pleuropulmonary disease. The indications for the thoracoscopic technique are very broad, but its role in the management of primary lung and oesophageal cancer has yet to be confirmed. Thus, the surgeon who uses the technique in these cancerous diseases should be prudent. In conclusion, these thoracoscopic procedures will play more important roles in the practice of thoracic surgery in the future.
INTRODUCTION
Surprising advances in the refinement of video technology have allowed the rapid expansion in video-assisted operative approaches in nearly all surgical areas. The thoracic area is no exception and it has played a very important role in thoracoscopic surgery. Although there is significant enthusiasm for video assisted thoracic surgery (VATS) procedures, caution is urged to prevent the over-application of the technique before is clearly demonstrated. Video assisted thoracic surgery is a new technique, not a new operation. Although a great number of intrathoracic procedures can be accomplished by VATS techniques, there is a question about whether it is a good procedure or not, and the consideration of cost cannot be ignored.
In spite of the ambiguous positive and negative impacts of thoracoscopic surgery, the techniques of VATS have been and will be advanced further.
History
The necessity of thoracoscopy became apparent following the success of Forlanini's introduction in 1882 of an artificial pneumothorax in the treatment of pulmonary tuberculosis. According to Braimbridge,1 the first thoracoscopic procedure was performed in 1910 by Hans Christian Jacobaeus, a professor of medicine, not surgery, in Stockholm. He used a primitive cystoscope to explore pleural space and mechanically broke pleural adhesions to facilitate the ‘collapse therapy’ for pulmonary tuberculosis. From there, this technique has become widespread all over the world, with serial reports of 1000 or more cases, in spite of a significant incidence of complications. Jacobaeus’ technique has been adopted with enthusiasm especially in Europe and America, and the techniques and instruments have been modified and developed. Moore2 in 1934 reported 1850 cases and Day3 had only two deaths in 923 patients of Jacobaeus's technique.
However, after the introduction of streptomycin in 1945 and other effective antibiotic therapies for tubercle bacillus, the age of enthusiasm for thoracoscopy ended. Thereafter, pleural biopsy was the only remaining role of thoracoscopy. After a period of near abandonment of this approach, since the early 1990s many thoracic surgeons have been re- exploring thoracoscopy, or VATS, as a means of accomplishing many intrathoracic procedures previously done through open thoracotomy. The main goal of this VATS procedure is to reduce post-thoracotomy-related morbidity and pain without sacrificing the therapeutic principles of open thoracic surgery. Several diagnostic and therapeutic thoracoscopic applications have been considered as the preferred approach to specific intrathoracic disease processes. Furthermore, several other VATS techniques have been investigated as potential alternatives to traditional open thoracotomy or sternotomy for the management of cardiothoracic pathologic states.
EQUIPMENT
The field of video-assisted thoracoscopic surgery is new and rapidly evolving, and has fueled industry to invest in and develop hand tools and accessory operative instrumentation. The equipment can be disposable or re-usable; both have advantages and disadvantages. It is necessary to choose judiciously after considering the economic situation or other conditions. An additional problem for surgeons is the shape of the tools. Because the handle of the tool is shaped as a ‘pistol grip,’ surgeons are not familiar with it, and it can become awkward to manipulate when detailed dissection is required. However, several companies have been developing designs more suitable for surgeons, so VATS will play a greater role in more complex thoracic surgical procedures in the future.
The basic equipment includes a fibreoptic light source with an associated video camera system and monitors. In addition, several specific thoracoscopic instruments including endoscopic graspers, clamps, and staplers are used. The most important piece of equipment for thoracoscopy is the optical system, because it is critical for optimal visibility when performing complex intrathoracic procedures. There are two main types of thoracoscopes available; flexible and rigid. The main advantage of the flexible thoracoscope is that it can be manipulated to visualize the entire thoracic cavity by changing the angle of the scope at the end. In spite of its limitation to low resolution capacity, the flexible scope is especially helpful when performing pleurectomies or pleurodesis, removing nodules in the lower lobes, or visualizing lesions in the posterior mediastinum. The rigid telescope is more popular and can have a 0-, 30-, 60-, or 90-degree lens. It can be made with a smaller diameter than the flexible. The smallest rigid scope is 3 mm in diameter, but recently a 2 mm diameter telescope has been introduced. This is a semi-rigid scope which contains thousands of fibers instead of a lens, to transmit light and images.
A recent development is the application of digital technology to image processing to increase resolution but at a reasonable cost. Several companies have been designing a dual-lens thoracoscope that yields a three-dimensional video image. Another concept is visible electromagnetic spectrum, which may help localize nodules by detecting a differential blood flow. With the current thoracoscopic instrumentation, cutting and suturing is difficult, tedious, and time consuming. Therefore, thoracoscopy has relied on stapling instruments to divide tissue. The most useful stapler is the Endo GIA stapler (Autosuture Co., Norwalk, CT, USA); a 3.5 mm depth staple is designed for use on the lung and a 2.5 mm staple is intended for use on vessels. There are a variety of surgical tools that have been developed. Most of these attempt to mimic standard thoracotomy instrumentation; for example, scissors, DeBakey forceps, right-angled clamps, and haemostasis. Some other percutaneous instruments are useful. They are finger-shaped fan retractors and thoracoscopic suction devices, which can be used for irrigation and cautery in one instrument, and specimen bags to facilitate tissue removals. Carbon dioxide insufflation into the pleural cavity may occasionally be quite useful because it maximizes visibility by assisting in collapse of the lung.
ANAESTHESIA
The current anaesthesia techniques for thoracoscopy involve in general two approaches; general and regional anaesthesia. General anaesthesia is commonly used. To induce collapse of the lung on the operative side, single-lung ventilation using either a double-lumen tube or bronchial blockers is indicated for thoracoscopic procedures. Sometimes CO2 gas is insufflated additionally. General anaesthesia is supplemented by local anaesthesia with lidocaine or bupivacaine combined with epinephrine. This minimizes the amount of bleeding from the port site, thereby minimizing contamination of the telescopic lenses and reducing the postoperative pain.
According to a detailed regional anaesthesia technique outlined by Boutin et al.,4 the technique emphasizes the use of lidocaine or bupivacaine combined with epinephrine to infiltrate skin over the port site as well as the intercostal muscle and the underlying pleura. The addition of epinephrine to the local anaesthetic reduces the amount of blood oozing from the pleural side of the port and thus minimizes blood contamination of the viewing telescope. The block of the satellite ganglion with injectable opioids is also useful. Once a pneumothorax is established, bupivacaine may be used to anaesthetize the parietal pleura. This involves a nebulizing technique directed at all aspects of the parietal pleura. Most authors recommend the use of adjunctive medications to provide sedation, analgesia, and amnesia. Current popular neuroleptic analgesics include droperidol, nefopam, midazolam, diazepam, or fentanyl. Boutin regularly carries out wide pleural and pulmonary biopsies using a local anaesthesia technique. Some surgeons commenced resection of apical blebs and sympathicotomy by utilizing this form of anaesthesia.5
STRATEGIC PLANNING AND BASIC PROCEDURE
As with any operative procedure, careful pre- operative and intra-operative planning is vital to achieve a safe and effective video-assisted thoracic surgical intervention. Careful patient selection for the VATS approach is vital to prevent inappropriate surgical interventions, prolonged operation times and unnecessary peri-operative morbidity. Although VATS is a useful means of evaluating the pleural space, primary use of VATS to assist in the control of a known unilocular malignant pleural effusion is questionable. Tube thoracotomy drainage and chemical sclerosis are certainly less morbid, inexpensive and effective management approaches for the simple pleural effusion.6 Similarly, an expeditiously performed lateral thoracotomy may be a more correct primary operative strategy for some patients.
Pre-operative planning for VATS approaches begins with a careful assessment of the chest radiographs and the computed tomographic (CT) scans, because it is vital to formulate the plan of the initial and subsequent intercostal access of the thoracoscopic and surgical instruments. After carefully analysing the scans, a surgeon must consider the disease process that is being dealt with and decide the operative plan. For example, it is preferred to carry out a VATS biopsy of diffuse interstitial lung disease from the right side of the chest. This is because the trilobed nature of the right lung permits more edges of the lung for achieving a safe endoscopic stapler application.
Almost all thoracoscopic procedures can be appropriately performed with the patient in the lateral decubitus position with the arm elevated on the operated side and the table maximally flexed to drop the patient's hip and shoulder away from the operative field. However, venous pooling of the lower extremities may result and should be noted. Skin preparation and draping are done identically to that for open thoracotomy procedures should the need for conversion to formal thoracotomy arise.
Proper placement of the ports for thoracoscopic procedures is of maximal importance. It is most suitable to place the scope within the fifth to the seventh intercostal space in the anterior-to-posterior axillary line because the intercostal spaces are quite wide in this anatomic area, permitting an easy panoramic view of the thoracic cavity. When there is a question of pleural adhesion, direct digital exploration of the intercostal access site, rather than blind trocar placement into the chest, is used to identify the presence of local pleural adhesions that can impede in pulmonary parenchymal injury. After the initial thoracoscopic exploration of the pleural cavity is conducted, further intercostal access for VATS instrumentation is achieved under direct thoracoscopic vision. The endoscopic instruments and thoracoscopic camera should be oriented in the same direction and toward the target of the operative procedure. If incomplete collapse of the lung is present, inflation with CO2, passed into the pleural cavity at a pressure below 10 mm Hg, is useful. On completion of the thoracoscopic procedure, careful haemostasis of the operative sites should be achieved and a chest tube is usually placed through one of the incisions.
INDICATION
Since the advantage of video-assisted thoracoscopic surgery for patients includes cosmetic considerations, low pain, earlier post-operative mobilization, and a shorter operation period in some indications, the approach has secured a firm place among the therapeutic options in thoracic surgery in recent times. Surgeons have demonstrated its increasing utility in the diagnosis and treatment of the pleura, lung, mediastinum, great vessels, pericardium, and oesophagus (Table 1). Another general indication for VATS is in patients at high risk, such as those with severe hypertension, heart failure, chronic obstructive pulmonary disease, or interstitial fibrosis of lung, if they are operated on with open thoracotomy.
The most common application of the thoracoscopic approach remains in the management of pleuropulmonary disease, for both diagnosis and therapy. However, one must remember that simple thoracentesis, pleural fluid examination, and needle pleural biopsy are still valid methods of diagnosing pleural disease. An area of controversy is its role in the management of primary oesophageal and lung cancer. It is doubtful that VATS will play a primary role in the treatment of these two diseases, because the patient may lose his or her one chance for cure. The potential drawback of VATS includes its overapplication, compromised surgery, misapplication in the management of oncologic disease, and the potential hazards of major uncontrolled haemorrhage and inadvertent undetected organ injury.
DISEASE
Pleural disease
Pleural diseases were the first to be managed with these minimally invasive surgical approaches. Indeed, diagnostic and therapeutic pleural applications continue to be the most universally accepted use of VATS. The view of the pleural space with thoracoscopy compares favourably with that obtained from direct view through a limited axillary, infra-mammary, or lateral thoracotomy.7
More reports on the usefulness of thoracoscopy for the diagnosis of pleural disease have been researched. For example, Harris et al. reported that thoracoscopy had a diagnostic sensitivity of 95% for malignancy and 100% for benign disease, in a series of 182 pleural effusions.8 Boutin et al. reported 96% of 215 undiagnosed pleural effusions could be diagnosed by thoracoscopy.9 The majority was discovered to have malignant conditions. For the diagnosis of pleural disease, thoracoscopy should be used when the less invasive methods of diagnosis, such as pleural fluid cytology and needle biopsy of the pleura, do not yield a diagnosis. When one performs thoracoscopy for diagnostic purposes, it is important to prepare to perform a procedure to create a pleurodesis at the time of surgery. A preferred method is the insufflation of 2–5 g of talc. The effectiveness of diagnostic thoracoscopy in producing a higher diagnostic yield than thoracentesis or unguided needle biopsy of the pleura is based upon the fact that many pleural malignancies are patchy in their distribution and guided biopsy can be performed easily and accurately thoracoscopically. In addition, thoracoscopy can release adhesions, decompress fluid loculations, and consequently, expose a large area of the pleural surface to the sclerosing pleural agent.
The VATS approach is also useful in managing a number of other pleural processes. Loculated pleural effusions, unorganized empyema, pleural based masses, and post-traumatic haemothoraces can all be managed. An empyema in the fibrinopurulent phase is best managed by disruption of the loculations and complete drainage of the infected space. This is easily accomplished with the use of thoracoscopy, which also permits inspection of the pleural space to determine whether additional surgical intervention is required. Heinz et al. reported that 67 patients with fibrinopurulent stage of empyema that did not respond to chest tube drainage and antibiotic therapy were treated by debridement with the use of the VATS technique.10 In contrast, thoracoscopy is not indicated in the management of a chronic empyema associated with a fibrous capsule. Bronchopleural fistulas are occasionally treated by thoracostomy tube drainage alone, but in most situations, surgical intervention is necessary to permit reclosure of the bronchus and coverage of the stump with vascularized tissue. In this situation, thoracoscopic techniques have been attempted recently.11 In the treatment of chylothorax VATS would be very helpful. With this VATS technique, earlier intervention is now favoured by many, especially if the patient's nutritional status is already poor. If the patient ingested full cream before the operation, the leakage is readily visible at surgery. Ligation of the thoracic duct is an almost invariably successful procedure which can be done by thoracoscopy.12,13
Mediastinal disease
Thoracoscopic approach to the anterior mediastinum
Thoracoscopy has been found useful for both the diagnosis and treatment of anterior mediastinal disorders and has been used increasingly for biopsies of anterior mediastinal masses and the excision of lymph nodes. Thymectomy can also be performed as well as excision of bronchial and pericardial cysts and other anterior mediastinal masses. According to the advances in both the instrumentation and technique, the application of these operations has increased.14
In the operative field, the patient is placed in the lateral decubitus position with the upper extremity being uplifted on the operative side with rotation of the patient somewhat posteriorly. In this position, the mediastinum and lung are more posteriorly located, which facilitates the dissection. A double-lumen endotracheal tube is passed for anaesthesia, and standard monitoring is performed. Thoracoscopic surgical interventions for excision of mediastinal masses follow the same steps and general rules as for traditional open thoracotomy. The isolation of mediastinal tumours, the ligature and division of vessels, is performed using the same technique as conventional surgery; endo-staplers, clip-applier, and endoscopic instruments, which allow manoeuvrability and guarantee the feasibility of these operations.
In the literature, the indications for these thoracoscopic operations are not yet clearly defined, but it is believed that this technique is indicated for well encapsulated benign mediastinal lesions and is feasible for larger non-infiltrating tumours, where great care must be taken to avoid vascular and nervous injuries.15 Complications in the thoracoscopic removal of well encapsulated mediastinal masses do not differ greatly from those of traditional surgical procedures. Even though the risk is small in the case of well encapsulated and benign masses, larger masses need great caution in order to avoid injuries to any of the major mediastinal vessels or to the nervous structures. Bleeding is undoubtedly the most concerning complication during thoracoscopic operations. Special care and attention must be paid to thymic tumours. As venous drainage of the gland to the innominate vein is through thin vessels, each must be isolated and clipped with care so as to avoid excessive traction and injury to the innominate vein. Additional caution is required to avoid any violation of the thymoma capsule during manipulation, otherwise pleural seeding can later appear.
Thoracoscopic approach to the posterior mediastinum
Improvement in technique and instrumentation allows the diagnosis and treatment of a diverse range of posterior mediastinal masses, including neurogenic tumours, oesophageal leiomyoma, paravertebral abscesses, and bronchogenic cysts. The thoracoscopic approach for a posterior mediastinal mass is performed with the patient placed in the lateral decubitus position under general anaesthesia with single lung ventilation. The operative table is tilted anteriorly to allow the lung and heart to fall away from the mass. As in all patients, an oximeter to monitor peripheral oxygen saturation is routinely used during collapse of the operated side. Trocar ports are placed slightly toward the anterior.
Thoracoscopic procedures for diagnosis, such as visualization and biopsy of posterior mediastinal masses, are appropriate only when other less invasive modalities have failed. Tumours of the posterior mediastinum can arise from any tissues or structures found there, including pleura, bone, lymph nodes, oesophagus, and sympathetic and parasympathetic ganglia. Most common neoplasms are benign neurogenic tumours and can be resected thoracoscopically without any difficulty. But apical neurogenic tumours are rarely operated on with thoracoscope because the tumour itself will obscure the operative field. Frequently detected on routine chest film, these tumours are often asymptomatic. A pre-operative CT scan should be obtained to demarcate the limits of the mass and to assess mediastinal invasion and potential involvement of the spinal cord by dumb-bell tumours. Thoracoscopic resection of such a lesion is contraindicated. Some surgeons successfully have performed single-staged thoracoscopic resection of a neurogenic mediastinal dumb-bell tumour using a combined posterior approach.16 Thoracoscopic procedure has also been proved to be easy, safe, and advantageous in the treatment of rare tumours, such as mature mediastinal teratoma17 and parathyroid tumour.18
In addition, this technique is used for anterior access to the thoracic spine. Mack et al. underwent thoracic spine procedures using thoracoscopy as the sole method of anterior approach in 95 patients.19 The performed procedures included discectomy for herniation, multilevel discectomy for correction of spinal deformity, corpectomy, and drainage of abscesses in intervertebral disc space. In addition, a thoracoscopic procedure can be performed for drainage and debridement of a mediastinal abscess resulting from descending necrotized mediastinitis.19 Because of the decreased morbidity of the thoracoscopic approach compared with thoracotomy and the improved drainage compared with cervical and thoracostomy drainage alone, thoracoscopic drainage should be considered for posterior mediastinal abscesses of any cause.
Lung disease
Blebs, bullae and interstitial lung disease
One of the first thoracic disease processes applicable to VATS intervention to attract the attention of the thoracic surgeon was primary spontaneous pneumothorax. Spontaneous pneumothorax is a fairly common disorder with an age-adjusted incidence of 7.4 cases per 100 000 person-years for men and 1.2 cases per 100 000 person-years for women.20 Surgical treatment of spontaneous pneumothorax in the past was fairly straightforward; thoracotomy, suture of the leaking lung or bullae resection, and pleurectomy or pleural abrasion. At present, VATS allows the same procedure to be realized as through a thoracotomy. Recovery from a thoracoscopic bleb resection and pleurodesis is much faster and the incidences in postoperative pain and morbidity rate are much lower than for an open approach. Consequently, thoracoscopy takes the place of limited open thoracotomy.
The candidate patients should undergo a high- resolution chest CT. Computed tomography scanning allows the exact identification of the morphology and sites of bullous formations, as well as the assessment of the most appropriate surgical strategy for removing these tissues. The VATS procedure is performed with the patient in the lateral decubitus position with a double-lumen endotracheal tube in place and prepared as for standard thoracotomy. In cases of bilateral disease, both sides of the thoracic cavity can be approached at supine position without changing patient's position. The stapling device is inserted in place with a margin of approximately 1 cm from the bleb on the normal lung tissue. Usually the upper part of parietal pleura is abraded to avoid recurrences. Wakabayashi described the use of the Nd:YAG and carbon dioxide laser to ablate the apical bullae and to thermally effect a mechanical pleurodesis.21 Nathanson advocated using preformed catgut endoscopic ligatures that are thoracoscopically introduced to endoloop beneath the bullae and ligate it at the base of the healthier lung parenchyma.22
The thoracoscopic technique is also performed for lung volume reduction surgery, using a linear cutting stapler or laser ablation as a current therapy for symptomatic emphysema.23,24 The novel technique of lung volume reduction surgery is designed to minimize trauma to the patient. The utilization of thoracoscopic incisions for this procedure may be preferred to minimize surgical trauma. Lung volume reduction surgery is performed to alleviate dyspnoea of selected patients with severe pulmonary emphysema, and to improve their pulmonary function, performance in daily activities and quality of life. By resection of destroyed lung parenchyma, the achievable improvements in function may consist of a reduction in hyperinflation, resulting in amelioration of diaphragm and chest wall mechanics, an increase of elastic recoil pressure, which augments expiratory flow rate accordingly, and possibly an improvement in gas exchange.
The resection is aimed at the most destroyed tissues, identified previously by CT scans and perfusion scintigraphy. After the instruments are inserted, the target areas are presented by endoscopic lung forceps and resected by successive application of endoscopic staplers with or without buttressing of the staple lines with bovine pericardium or thin Goretex. Wakabayashi described the results of applying thermic energy onto the surface of emphysematous lungs by VATS using a sapphire contact Nd:YAG laser, but more frequent recurrence has resulted.21 The goal of this procedure, called thoracoscopic laser pneumoplasty, is to achieve a shrinking of the underlying lung parts.
Naunheim et al. reported the results of a unilateral thoracoscopic resection.25 They achieved significant functional improvement, in spite of less magnitude than that in a bilateral procedure. However, unilateral resection may be indicated for unilateral disease predominantly, or to patients with contraindications to bilateral operation; pleurodesis or a previous thoracotomy. Almost all other patients would undergo bilateral resection.24
Diffuse interstitial lung disease, due to a wide variety of conditions, is amenable to diagnosis by means of clinical evaluation, bronchoalveolar lavage, transbronchial biopsy, and lung biopsy. The recently introduced technique of thoracoscopic wedge biopsy provides the potential advantage of better selection of biopsy sites and reduced postoperative pain compared with the related properties in standard open lung biopsy. Therefore, VATS lung biopsy has become a common alternative to open lung biopsy for diagnosis of localized and diffuse lung disease.
Patients should undergo general anaesthesia and be intubated using a double-lumen endotracheal tube rather than a single-lumen tube. Biopsy sites are selected on the basis of CT scan data and intra-operative findings. Biopsy material should be obtained from at least two sites; an area of severely diseased tissue and a less involved region. In bilateral disease, the biopsy is preferred from the right lung as it is technically easier compared with the left due to the presence of three lobes and the corresponding fissures. Biopsy is performed by wedge resection using endo-staplers. The amount of tissue recovered during VATS lung biopsy is usually adequate and comes from a representative area visualized at thoracoscopy.
Bensard et al. found 95% accuracy in VATS lung biopsy and concluded that it is as safe and effective as open lung biopsy in the evaluation of diffuse interstitial lung disease.26 Thoracoscopic management is especially critical for immunosuppressed patients. Currently many AIDS patients, not diagnosed by bronchoscopic biopsy or bronchoalveolar lavage, undergo thoracoscopic lung resection for definitive diagnosis. In addition, transplant patients who present with infiltrates on chest X-ray or CT scan are now aggressively evaluated with thoracoscopic lung biopsy.27 However, thoracoscopic lung biopsy has higher procedure-related costs than open lung biopsy,28 although it has several reasons to be selected as the method of choice. The role and advantages of thoracoscopic technique compared with open biopsy need to be investigated further.
Other benign pulmonary lesions
Thoracoscopy is not only a diagnostic but also a therapeutic procedure in the presence of an indefinite solitary pulmonary nodule. Patients with indeterminate pulmonary lesions usually require a definite diagnosis for proper management. The conventional diagnostic procedures such as bronchoscopy and transthoracic needle biopsy sometimes fail to obtain a decisive answer, thus a more aggressive diagnostic procedure will be needed. Thoracoscopy can also play an important role when a lesion is embedded in the parenchyma. Thoracoscopic wedge resection including nodule may be very helpful for diagnosis and treatment of indeterminate pulmonary lesions. When the tumour is located centrally, a video-assisted thoracoscopic lobectomy is also a possibility.
The current role of VATS in the management of tuberculosis patients is unclear and limited. Drainage of empyema, wedge lung resection, lobectomy, pleural biopsy, and decortication can be done using VATS. According to one series, VATS is safe and effective for achieving the diagnosis of tuberculosis through pleural biopsy or wedge lung resection of indeterminate pulmonary nodules.29 It is particularly useful for those patients who are debilitated, thus making them poor candidates for conventional open surgery. In patients with trapped lung or tuberculous empyema, VATS could achieve full lung re-expansion with minimal morbidity. Nevertheless, therapeutic lung resection using VATS in tuberculosis patients is technically demanding and potentially hazardous.
Lung cancer
Despite a plethora of technological advances, there has been only minimal improvement in the surgical treatment of carcinoma of the lung during the past years. The advent of video-assisted thoracic surgical techniques, however, is opening up new vistas and providing unimagined options for more accurate diagnosis, more precise staging, and more specific resections of lung tumours. Currently, VATS is used widely for staging, diagnosis, and treatment of lung cancers.
Accurate staging of lung cancer is the cornerstone for directing treatment and estimating prognosis. Radionuclide scans and CT assessment have limited value in non-invasive pre-operative staging. Pleural carcinosis without pleural effusion in particular is usually not revealed by CT due to the minimal dimensions of the lesions. Similarly, in the case of hilar lesions, it is always difficult to distinguish simple contact from true infiltration of the mediastinum in vascular structures. Moreover, mediastinoscopy is limitated to sampling aortopulmonary window, posterior subcarinal or perihilar lymph nodes. Thoracoscopic staging can be performed as the first step of a surgical operation to explore the entire pleural cavity. When surgical manoeuvres are properly carried out, hilar and mediastinal structures as well as every lymph node level can be explored easily; from the paratracheal to the paraoesophageal nodes, from the apex to the diaphragm. These procedures offer a minimally invasive means to accurately stage lung cancer and avoid untherapeutic thoracotomy. Huh et al. recommended routine thoracoscopy for adenocarcinoma because of abundant indolent pleural seeding.30 Champion et al. demonstrated accurate thoracoscopic staging by comparing closed video-imaged thoracoscopic staging of patients who subsequently underwent open thoracotomy and re-staging at the time of therapeutic resection.31 In addition, Roviaro et al. reported that by using thoracoscopic operative staging it was possible to decrease the rate of exploratory thoracotomies to less than 4%.32 However, there are disadvantages to the thoracoscopic technique. Thoracoscopy has a limitation when assessing contralateral and upper mediastinal node evaluations. A combination of thoracoscopy and mediastinoscopy may provide more accurate N-staging of lung cancer than either procedure alone or a non-invasive staging procedure.33
Since Lewis et al. reported on thoracoscopy-assisted lobectomy,34 many institutes have attempted the procedure in patients with primary lung cancer. However, at present, no established evaluation has been made of the therapeutic effects of the thoracoscopic lobectomy compared with those of lobectomy under standard thoracotomy. In addition, the indications for thoracoscopic lobectomy are still unclear. Because lymph node dissection in patients with lung cancer has played an important role in the prognosis of the patients, usually only patients with clinical and radiological stage I non-small cell lung cancer have been considered for thoracoscopic resection. If the same number and the same extent of lymph nodes could be dissected in patients whether undergoing VATS lobectomy or lobectomy via standard thoracotomy, VATS lobectomy would be suitable for patients with lung cancer of stages I or II.35 However, in patients with adenocarcinoma, there are so many skipped lymph-node metastases in the superior mediastinum that VATS lobectomy may be more suitable for patients with a histological typing such as squamous cell carcinoma.35
The operative technique is similar to other VATS techniques. At present, much of the endoscopic equipment is inadequate or suboptimal for major chest operations. Therefore, a 5–8 cm access thoracotomy, in which standard thoracic instruments, such as scissors, forceps, and right-angled dissectors, could be introduced into the chest, would be very useful. This access site can also be used to facilitate delivery of a particularly bulky specimen. The hilar structures are individually dissected and divided in a manner entirely analogous to an open procedure. The vessels, bronchi and fused sections of fissure are divided using endoscopic stapling devices. Before applying a vascular stapler on any large vessels, a vascular clamp should be placed centrally to avoid potential haemorrhage in the case of a malfunctioning stapler. The specimen should be placed in a plastic bag in the chest prior to extraction through the access incision. The number of cases of port site cancer recurrences after thoracoscopy is not negligible.36
The VATS technique can be considered as an option in managing pulmonary metastases. However, because of the limitation that thoracoscopic surgery does not permit careful palpation of the entire lung, thoracoscopy is a valid alternative to sternotomy and thoracotomy in only selected cases.37 In one series, additional metastasis was identified at thoracotomy in 56% of patients who had already been treated for pulmonary metastasis with thoracoscopy.38 Video-assisted thoracoscopy surgery should be used only as a diagnostic tool in managing pulmonary metastasis, and a thoracotomy is required to achieve complete resection, which is the major survival prognosticator for satisfactory long-term results in pulmonary metastasis.
Oesophageal disease
Achalasia is a neurological abnormality of the oesophagus characterized by progressive dysphagia, regurgitation, pulmonary complications and weight loss. Extramucosal oesophageal myotomy affords the best long-term results in the relief of achalasia. However, because of the discomfort and other morbidity caused by the laparotomy or thoracotomy, balloon dilatation replaced myotomy as the most popular treatment. Soon after introduction of endoscopic surgery, surgeons began to perform Heller myotomies using minimally invasive techniques, either thoracoscopy or laparoscopy.39 It soon became evident that the attendant patient discomfort, hospital stay, and return to work were much less for these minimally invasive procedures than those associated with thoracotomy or laparotomy. As thoracoscopic myotomy shares the advantages of the conventional Heller's myotomy over balloon dilatation, but with little morbidity associated with its access, a strong case can be made for it being the procedure of choice in the management of achalasia.39,40
These thoracoscopic techniques have also been applied to oesophageal cancer surgery. Decreasing the mortality and morbidity rates associated with oesophageal surgery remains one of the important goals for surgeons. Avoiding the consequences of thoracotomy in fragile patients might be the first step toward this goal as respiratory complications from thoracotomy are the most common and serious problems. Until recently, however, the transhiatal oesophagectomy introduced by Orringer and Sloan had been the only alternative to thoracotomy,41 but it had disadvantages inherent in the blind dissection involved. With the advent of operative thoracoscopy, it became possible to apply this advanced technique to the resection of the thoracic oesophagus. Thoracoscopy has been reported to be associated with significantly less morbidity and has provided excellent visualization of the operative field. Law et al. reported that thoracoscopic approach was feasible and as safe as the conventional transthoracic resection.42 It was associated with significantly less blood loss and the overall operating time was not longer than that of transthoracic resections. However, one question remains: can radical mediastinal lymphadenectomy be performed safely by means of thoracoscopy with the same level of completeness as is achieved with a conventional posterolateral thoracotomy? Akaishi et al. could perform thoracoscopic en bloc total oesophagectomy with mediastinal lymphadenectomy, but extensive laboratory experience with animals was crucial to achieve a high success rate in a clinical setting.43 Thoracoscopic oesophagectomy and mediastinal lymphadenectomy are feasible and can be performed safely, but these methods should be applied very cautiously.
MISCELLANEOUS ASPECTS OF THORACOSCOPY
Thoracoscopy for autonomic disorders
Sympathetic denervation of the arm, the hand, and the heart may now be performed using minimal thoracoscopic procedure. Thoracic sympathectomy for an autonomic disorder, hyperhidrosis, was performed first by Kotzareff in 1920 using an open method.44 The effect of thoracic sympathectomy has since been fairly well described; however, because of the magnitude of the procedure, the operation has not been commonly used. In 1951, Kux described a method for thoracoscopic electrocautery of the sympathetic nerve.45 Since then, transthoracic endoscopic sympathectomy has stood the test of time as the treatment of choice for sympathetic palmar hyperhidrosis. The principal physiological effect expected from sympathectomy is the release of vasomotor control and hyperactive tone of the arterioles as well as smaller arteries that have a muscular element in the vessel wall. The circulation to the skin, peripheral extremities, and bone is vastly improved, but the effect on the skeletal muscle of the arm is minimal. Its other function is the control over cutaneous sweating, which is profuse and undesirable. Sympathectomy eliminates perspiration in that quadrant of the body, with an attendant increase in perspiration elsewhere.
Surgical technique varies from anaesthesia to level of sympathetic denervation. Single-lumen endotracheal tube anaesthesia is now more commonly used than double-lumen endotracheal tube anaesthesia and some advocate local anaesthesia.44,46 The various methods include one to three skin incisions, room air to carbon dioxide insufflation, destruction of the second (T2), the third (T3), and the fourth (T4) sympathetic ganglia to destruction of the T2 ganglion only, and total removal of the target sympathetic chain (sympathectomy) to division between the ganglia only (sympathicotomy). Similarly, there are many different ideas about techniques. With introduction of a fine 2 mm scope, the operation can be done fairly simply, and operative scars are barely visible.45 However, the essence of the operation is the destruction of the second sympathetic ganglion. To do this, a surgeon should be familiar with locating the first rib in the operative field. Wong47 showed how to identify the first rib: (i) the first rib is often visible below the distal end of the intrathoracic segment of the subclavian artery; (ii) following the faint curve of the first rib from the point below the distal intrathoracic subclavian artery toward the dome is often feasible; (iii) the invisible part of the first rib just below the dome of the pleura is palpable with the diathermy bar; and (iv) the first rib, when conspicuous, is often not as parallel to the second rib as is the third rib. A common side effect of sympathectomy has been compensatory sweating of the trunk (45%), but in most cases, it is a minor problem.44 Chuang et al. recommended intra-operative monitoring of palmar skin temperature, because it yields useful information about the location of the sympathetic segment and confirmation of their entire ablation by endoscopic thoracic sympathectomy.48
Splanchnicectomy has been shown to be effective for the control of intractable pain in some patients with pancreatitis, pancreatic cancer, and related conditions. However, use of this procedure has been limited owing to the previous necessity of an abdominal approach to perform the procedure. With the advent of thoracoscopic surgery, this trend is now being re-evaluated. Thus, some surgeons have reported many cases of the thoracoscopic thoracic splanchnicectomy.49 They resected and coagulated the sympathetic chain at a level from T5 to T9, and maintained that this technique was a safe and reliable procedure for the pain relief of the pancreatic disease. Truncal vagotomy can be performed by thoracoscopy. Additionally, other diseases like Raynaud's phenomenon, Raynaud's disease, causalgia, reflex sympathetic dystrophy, and vascular insufficiency of the upper extremity can also be indications for performing dorsal sympathectomy using the thoracoscopic technique.50
Cardiovascular disease
The role of VATS in the management of cardiovascular diseases has also been evaluated. The first attempt was performed in the area of the pericardium. In patients with symptomatic recurrent pericardial effusion, fenestration of the pericardium is a therapeutic operation if diuretic therapy and repeated puncture fail to control the effusion permanently. In recent years the thoracoscopic technique, as a minimally invasive method, has also been applied to patients with recurrent pericardial effusions caused by pericarditis, malignancy or other disorders. This technique provides optimal visualization of the pericardium combined with minimal operative trauma.51 Pericardiectomy is also a possible indication for this technique. One advantage of thoracoscopic pericardiectomy is that it allows pulmonary or pleural process to be managed simultaneously.
Recently many surgeons have described a video-assisted coronary artery bypass grafting procedure using the internal mammary artery (IMA).52–54 They harvested the left internal mammary artery using solely a thoracoscopic technique and revascularized the left anterior descending artery (LAD) by means of a 4 cm left thoracotomy without cardiopulmonary bypass.52 This technique allows complete mobilization of the IMA and division of all its side branches. This avoids the potential risk of steal, and should make reoperation by sternotomy safer because the IMA is not attached to the posterior chest wall. Patients who have had an operation like this can return to work, including physical labour, within 1 to 2 weeks because sternal healing is not an issue. Moreover, this technique is also more useful for older patients. Furthermore, some surgeons reported several cases of transmyocardial laser revascularization performed thoracoscopically to treat patients with end-stage coronary artery disease and severe disabling angina.55,56
The VATS technique has also been used in patent ductus arteriosus (PDA) interruption. This was first introduced in 1993 by Laborde et al.57 Patent ductus arteriosus is a frequent and relatively simple congenital heart disease. Many obliterating procedures have been developed, one of which is the transcatheter occlusion technique. This procedure obviates the need for an operation in up to 92% of PDA patients, but concern has been expressed regarding the high residual shunt rate (34% at 1 year), ductal size limitations (not more than 8 mm), and patient size restrictions (not less than 4 kg). In addition, complications such as coil embolization, haemolysis, and bacterial endocarditis have been reported.58 However, VATS ligation provides not only a safe, minimally traumatic, and rapid method but also an effective means to interrupt PDA flow, with residual flow in only 2.1% of cases.59
Video techniques have been used in many centres to assist with pericardial patch placement for implantable defibrillators. This technique has many advantages. It allows lower defibrillation thresholds than subcutaneous patches and also offers enhanced visualization and less morbidity than subxiphoid, subcostal, or thoracotomy.60
PRESENT AND FUTURE ROLES FOR THORACOSCOPY
The past several years have witnessed the evolution of video-assisted thoracoscopy. The performance of this procedure has now been moved from university centres to the community hospitals, and it seems the number of this procedure performed will soon be parallel to that of conventional open procedures. However, before this procedure is performed there are several preceding conditions. The first condition is that the surgeon has to be good at this procedure. There is a big gulf between the practised surgeon and the inexperienced. Therefore, VATS training should be within the armament of every thoracic surgeon today. Yim61 described five levels of training; (i) didactic lectures; (ii) demonstration of procedures; (iii) practice on simulators; (iv) animal surgery; and (v) preceptorship. The first four are usually provided in training courses or workshops, while the last is required as an attachment to a training centre. The ultimate goal is to integrate all these into the surgical residency programs. Developments in the virtual reality module may revolutionize training in the future.
The second condition is the currently available instrumentation. It is true that the combining of the miniaturized video technology with thoracoscopy now allows surgeons to perform a variety of thoracic procedures percutaneously. However, at present, the instrumentation used for video-assisted thoracoscopy lags far behind the video capability, making the thoracoscopic procedure not as comfortable to perform as open surgery. Nonetheless, as numerous manufacturing companies and surgeons are working rapidly to bridge this gap, we believe that we will soon see a plethora of new and exciting instrumentation becoming available that will enable endoscopic procedures to be as comfortable as open surgery.
The third concern is the economics of thoracoscopy. Indeed, at present, there are few procedures that can be done more cheaply by video-assisted thoracoscopy than by conventional open technique. In these settings, hospitals and physicians will have to work stringently to curb the costs of video-assisted thoracoscopy. Ways in which costs can be reduced are through the use of non-disposable instruments, standardization of the operative setup fees, stapler companies reducing the prices of their products, and a closed packet price for a given procedure. Finally, the last concern is the application of this technique in certain procedures. This is to define the role of the VATS in the management of certain conditions. As we stated earlier, the indications for VATS are very broad, so it seems a surgeon can operate on almost all thoracic diseases using the VATS technique. However, its role in the management of primary oesophageal and lung cancer has yet to be confirmed. Thus, the surgeon who would apply the VATS technique to cancerous diseases should be prudent because the patient may have only one chance for a cure. With the advance of technology and more surgeons interested in this technique, the thoracoscopic procedure will flourish. In conclusion, these thoracoscopic procedures will play a more important role in the practice of thoracic surgery in the future.
