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* From the Division of Pulmonary and Critical Care Medicine, University of California, San Diego, CA.
Correspondence to: Henri G. Colt, MD, FCCP, Associate Professor of Medicine, Chief, Interventional Pulmonology, UCSD Medical Center, La Jolla, CA 92037; e-mail: hcolt{at}ucsd.edu
Abstract
Thoracoscopy has provided chest physicians and surgeons with an opportunity to rethink their approach to patients with pleural and pulmonary disease. In this brief review, several methods pertaining to videothoracoscopic procedures are described, followed by a summary of the major indications for this procedure. The question of whether a thoracoscopic approach to diagnosis or treatment could replace more conventional approaches is addressed for several disease processes. Finally, a few thoughts about future directions of this emerging technology are shared.
Key Words: pleural disease • technology • thoracoscopy • video-assisted thoracic surgery
Evolving endoscopic surgical techniques, regardless of whether skin incisions are required, continue to revolutionize patient care. Possibly the day will emerge when a group of endoscopic surgical specialists is capable of performing a variety of procedures crossing over several organ systems. After all, some might say a scope is always a scope.
It is not surprising that our sense of social responsibilities as well as medical curiosity incite us to seek new and potentially less invasive ways of performing diagnostic and therapeutic chest procedures. The endoscopic surgery revolution is a direct result of such innovations. For readers wondering how these emerging technologies and novel procedures will safely find their way into mainstream medical and surgical practice, rest assured: procedural expertise will be rapidly acquired once we introduce new core curriculums: I predict, for example, that training capabilities will soon be enhanced by the incorporation of virtual reality simulators.
The purpose of this supplement, however, is not to focus only on the future, but to summarize the present role of emerging technologies in pulmonary practice. In this regard, the inclusion of thoracoscopy in such a supplement is indeed welcome. Although endoscopic visualization of the contents of the pleural space has been performed in Europe since Jacobaeus, the procedure was seldom performed in the United States. For reasons that are still unclear, thoracoscopy had fallen into near total oblivion in this country during the last 50 years.
During this decade, however, thoracoscopy found its way back into mainstream chest medicine and surgery. This is due, in part, to the impact of laparoscopic surgery on general surgical practice, prompting many thoracic surgeons to modify proven open surgical techniques so that therapeutic procedures could be performed through smaller incisions using specially designed instruments and videotechnology.1 To their credit, thoracic surgical societies have done a remarkable job of describing thoracoscopic surgical techniques, publishing prospective and retrospective reports, introducing training guidelines, and evaluating novel surgical techniques so that video-assisted thoracic surgery could find a proper place among surgical management strategies.
The thoracoscopic window to the pleura was also opened by a handful of pulmonologists who pushed the envelope, so to speak, in their efforts to efficiently and effectively diagnose patients with pleural disorders or manage patients with incurable malignant pleural disease. Techniques of thoracoscopic pleural biopsy, fluid drainage, and pleurodesis are now recognized components of the interventional pulmonologist’s practice. Sessions about thoracoscopy and its role in the management of patients with simple and complex pleural diseases are included in today’s postgraduate courses and pulmonary society meetings. Undeniably, the bridges being built between pioneers in "interventional pulmonology" and their thoracic surgery colleagues will result in greater collaborative efforts among present and future generations of health-care providers.
In the following paragraphs, the technology and methods pertaining to videothoracoscopic procedures are reviewed. A brief description of the major indications for these procedures follows, accompanied by comments on whether a thoracoscopic approach to diagnosis or treatment could replace more conventional approaches. Finally, the closing paragraphs are devoted to a discussion of the potential limitations of thoracoscopy and thoughts about future directions.
It goes without saying that I beg the reader’s indulgence for not providing herein an inclusive review of current knowledge and practice of thoracoscopic procedures: a simple MEDLINE search (English language, years from 1990 to 1998) using only thoracoscopy as a key word yielded 1,035 citations. Because of space limitations, I have intentionally limited references to a few selected review articles and original research published in various international journals, representing a broad scope of thoracoscopic practice in both the chest physician’s and chest surgeon’s literature, and for the most part, published since 1995. To the many colleagues and fellow investigators who have published articles in these areas, but whose names I have not cited, your forgiveness is appreciated.
Technology and Instrumentation
For many years, visualization of a closed space such as the pleural cavity was possible through a rigid Hopkins lens telescope attached to a cold light source. Only the operator was able to visualize the contents of the pleural space, although occasionally, a single assistant could watch through a "teaching head" attached to the eyepiece of the telescope. Teaching heads reduced the amount of light transmitted through the telescope, and were also extremely expensive, costing several thousand dollars. In addition, the operator could use only one hand to manipulate instruments because the other hand held the telescope. The same was true for the assistant who held the teaching head.
Thoracoscopic instruments were designed to facilitate operative procedures. Forceps, graspers, lung manipulators, cautery and cutting devices, suction/irrigation instruments, and a variety of disposable and reusable pleural trocars and cannulas are currently available. Many of the same instruments used in open thoracic surgery can be used in thoracoscopic surgery; it is really the development of the endoscopic stapling device that expanded the scope of thoracoscopic practice.
Of course, the introduction of videotechnology into medical practice also changed our acceptance of thoracoscopic procedures. Not only have optics considerably improved—telescopes used today have greater depth of field, magnification, and arc of vision—but now multiple assistants and observers can watch an entire procedure. Visualization of the contents of the pleural cavity is facilitated by a videocamera that is attached to the eyepiece of the rigid telescope. The size and quality of these cameras has considerably improved in recent years, and the addition of video makes viewing, documentation, and assisting during procedures far easier than in the days of direct visualization. Newer telescopes magnify the subject being visualized (usually about 4x for a 7-mm rigid telescope), and the increased availability of couplers of varying sizes allow greater depth of field and increased field of vision without distortion to enhance visibility.
Image size on the video monitor is affected by the aperture of the telescope, coupler size, and camera sensor size. The larger the coupler, the greater the magnification of the image. Unfortunately, this also decreases the amount of light being transmitted into the already large and relatively dark pleural cavity. Light sources today, however, are able to autoregulate the amount of light being transmitted through fiberoptic light cables, although many operators prefer to manually adjust these light controls.
Images are usually recorded using a VHS or Super VHS (SVHS) video recorder/player. It is fascinating that most procedure suites and operating rooms today are stocked with expensive carts and high-grade equipment that is rarely, if ever, used to its full capacity. In fact, for routine patient care purposes, a single-chip videocamera, a basic single standard medical-grade monitor or other video display, and simple VHS videorecorder amply suffice. With a single-chip camera, a segmented multicolor filter is often placed over a single sensor. Although detail is reduced, most physicians are unable to tell the difference compared with a far more expensive three-chip camera.
For thoracoscopists who require quality images for preparation of educational materials such as CD-ROMs, however, higher-grade equipment is often desirable. Not surprisingly, the costs associated with the acquisition of high-grade equipment can be excessive. A three-chip camera, for example, may cost as much as $12,000. In addition, these cameras are bulkier, heavier, and less comfortable to handle. A three-chip camera splits light into the three separate colors (red, green, and blue, or RGB). The video signals are then distributed as separate red, green, and blue signals with separate synchronizing pulses, as a combined composite video signal, or as two separate signals (known as luminance and chrominance, or Y/C).
The image is recorded onto a typical VHS recorder (with a line resolution of only 250 lines), or an SVHS video recorder (with a line resolution of > 400 lines). It is noteworthy that the conventional television screen has a line resolution of only 320 vertical lines, although more advanced video displays have a resolution of about 560 lines. By recording master images on SVHS rather than VHS, dubs (copies) will be of greater quality. The costs of a good SVHS deck is approximately $1,200 (about $2,500 for a medical-grade deck), compared with less than $400 for a VHS deck; the SVHS videotapes used daily are also more costly than VHS tapes. SVHS tapes cannot be viewed on VHS decks (which are the decks most people have at home next to their television sets), so subsequent editing and dubbing onto VHS is mandatory. Of course, with higher-quality television sets and the advent of the digital versatile disc, or DVD, SVHS inputs may soon become commonplace for in-home use.
Thoracoscopic exploration, however, is unlikely to undergo a radical change in the immediate future. Certain advances are necessary to improve documentation sources and to keep up with changes occurring in the world of communication, such as transmission over the World Wide Web. Eventually, images will be captured and recorded digitally before being transferred to CD-ROM for editing and storage. These changes will not be required, however, for the majority of thoracoscopists using videotechnology for simple observation and documentation.
Eventually, smaller telescopes with excellent illumination and visualization capabilities may be used for microthoracoscopy; a thoracoscope with distal charge-coupled device will be developed2 ; and an enhanced flexible fiberoptic videothoracoscope may find its way into the same day procedure suite à la flexible fiberoptic bronchoscopy.
Clinical Applications
Thoracoscopy is usually performed through one or several small, < 2-cm skin incisions made along the intercostal spaces. Patients are placed in the lateral decubitus position, involved side up, although some procedures, such as a thoracic sympathectomy, are performed with patients in the supine position. Pleural trocars can also be safely placed in the axilla, so that axillary thoracoscopy can potentially precede an axillary thoracotomy. IV sedation and local anesthesia are administered using techniques similar to those employed when making a chest tube insertion incision. Many operators prefer general anesthesia with single- or double-lumen endotracheal intubation performed in an operating suite. Certainly, the operating room is the accepted procedural area for diagnostic and therapeutic procedures such as lung biopsies, decortication, or cardiovascular interventions.
Many procedures limited to removal of pleural fluid, visualization, and biopsy of parietal pleura can be performed through a single skin incision made in approximately the fifth to seventh intercostal space along the lateral chest wall of the involved hemithorax. When a 5- to 10-mm pleural trocar and cannula are inserted through the incision, the parietal pleura, diaphragm, and lung are well visualized. Pleural fluid is evacuated and parietal pleural biopsy specimens are obtained from both normal- and abnormal-appearing areas. A chest tube is placed through the incision site and connected to a suction device, and the lung is gently reexpanded. Because the duration of chest tube drainage can be only a few hours, many patients are discharged the same day. In years past, this type of procedure was commonly referred to as pleuroscopy. Today, because of the very minimally invasive nature of the procedure, it has become known as "medical thoracoscopy."3 Complications such as bleeding (from parietal pleural biopsy), lung perforation (during trocar insertion), or infection (from inadvertently using nonsterile techniques) are extremely rare.4
Advanced diagnostic and therapeutic procedures are usually performed in an operating suite. Multiple incisions allow the introduction of biopsy forceps, endoscopic scissors, electrocautery, suction-irrigation instruments, and grasping forceps to allow greater mobilization of the lung, removal of fibrin deposits or blood clots, and sectioning of adhesions that prevent complete inspection of the pleural space and mediastinum. Sometimes these adhesions also inhibit complete lung expansion; they may also maintain patency of visceral pleural tears in patients with spontaneous or secondary pneumothorax. In patients with complex pleural effusions, suspected underlying trapped lung requiring an attempt at reexpansion using positive pressure ventilation, empyema, and multiloculated pleural effusions from infection or malignancy, the pleural space and mediastinum can be safely explored using general anesthesia and multiple access sites. Although comparative studies have not been performed, it is possible that complication rates may be increased in this setting because of the increased morbidity of patients undergoing these procedures, the use of general anesthesia, and the invasive scope of procedures being performed.
Pleural Effusion of Unknown Etiology
Algorithms for investigating pleural effusion of unknown etiology
typically begin with thoracentesis. Because cytologic examination is
diagnostic in only 60 to 80% of patients with metastatic pleural
involvement and in < 20% of patients with mesotheliomas, however,
thoracoscopic parietal pleural examination and biopsy present an
exciting opportunity to achieve earlier diagnosis.5
Most experts agree that when the initial evaluation of a pleural effusion is nondiagnostic, especially when neoplastic disease is suspected, thoracoscopic exploration and parietal pleural biopsy should be considered.6 The diagnostic accuracy of thoracoscopy is between 90 and 100%, compared with an approximate sensitivity of 44% for closed needle pleural biopsy and 62% for fluid cytology; false negatives occur most frequently in cases of early malignant mesothelioma. If the patient has a malignancy and negative cytology on thoracentesis, thoracoscopy is preferred over closed needle pleural biopsy because it will establish the diagnosis in > 90% of cases.
Tuberculous Pleurisy
The greater debate is whether thoracoscopy is warranted if
tuberculosis is high on the list of differential diagnoses. In
exudative pleural effusions due to tuberculosis, the diagnostic yield
of a closed needle biopsy is 70 to 90%. Thoracoscopy is usually
unnecessary, therefore, to establish the diagnosis of a tuberculous
effusion. A combined yield of only 6% for thoracoscopy preceded by
negative thoracentesis and closed needle pleural biopsy has been
reported. Thoracoscopy may be beneficial in difficult diagnostic
situations, however, when lysis of adhesions is necessary, or when
larger amounts of tissue are warranted to assure diagnosis when drug
resistance is suspected.
Malignant Mesothelioma
Although malignant mesothelioma may be suspected based on a
history of asbestos exposure, symptoms, radiographic findings of
pleural fluid, thickening, absence of contralateral shift of the
mediastinum, and clinical course, diagnostic confirmation is often
difficult. Pleural fluid cytology ranges from 4 to 77%, and
representative specimens from closed needle biopsy are rarely of
sufficient size and number to allow the full battery of
immunohistochemical stains and electron microscopic examination for
definitive diagnosis.7
Even with thoracoscopy, the
accuracy of diagnosing mesothelioma may suffer because of inadequate
visualization due to extensive adhesions and the inherent difficulties
in pathologic identification of this tumor.8
Thoracoscopy
allows removal of large, full-thickness specimens from several involved
areas, making it potentially preferable to open pleural biopsy by
minithoracotomy, and most certainly preferable to lateral thoracotomy.
Symphysis between visceral and parietal pleural surfaces and the
absence of pleural fluid can make these procedures technically
challenging. For patients not considering intrapleural chemotherapy or
surgical resection, pleurodesis can be performed at the time of
diagnostic thoracoscopy in order to prevent fluid reaccumulation and to
delay the onset of life-threatening dyspnea. Although tumor growth
through thoracoscopic incision sites has been described,9
it is probably less frequent than reported. Prevention is possible by
treating the area surrounding the incision sites with radiation.
Patients should be warned that such prophylactic radiation could
potentially make them ineligible for some clinical trials.
Malignant Pleural Effusions
In addition to diagnosis, an important indication for thoracoscopy
in patients with malignant pleural effusions is
pleurodesis.10
Complete evacuation of pleural fluid,
maximization of lung expandability by removing adhesions, and
pleurodesis by talc insufflation (also known as talc poudrage) results
in short- and long-term success rates of > 90%.11
Distribution of sterile, asbestos-free, US Pharmacopeia–approved talc
powder on all pleural surfaces is confirmed by thoracoscopic
visualization. Following pleurodesis, low-grade fevers should be
expected in up to 30% of patients, and hospitalization duration
averages 4.8 days. Pleurodesis can also be achieved by pleurectomy
using standard dissection techniques or hydrodissection.12
Because survival of patients with advanced pleural carcinomatosis is
often short, the risks and benefits of thoracoscopic pleurodesis must
be carefully weighed against those of repeat thoracentesis, tube
thoracostomy, or bedside pleurodesis through an indwelling chest tube.
Recurrent Pleural Effusions of Benign Etiology
Recurrent pleural effusions of benign etiology are frequently
caused by heart failure, cardiac surgery, nephrotic syndrome,
connective tissue diseases, and other inflammatory disorders.
Thoracoscopy may be warranted when recurrent effusions cause symptoms
and are not controlled by repeated large-volume thoracentesis. Usually,
pleural biopsy specimens are obtained to exclude infectious or
neoplastic etiologies, and pleurodesis is performed. Results are
usually excellent when talc is used, with success rates varying from to
65 to > 90%.
Lung Cancer
Most pleural effusions associated with lung cancer result from
direct carcinomatous involvement of the pleura. Even patients in whom
cytologic examination of pleural fluid is negative are often found on
thoracotomy to have unresectable lesions. Thoracoscopy is preferable to
thoracotomy for identifying this small group of patients who could
potentially benefit from a surgical resection. Thoracoscopy is also
useful for staging both lung and esophageal cancer because it may
complement cervical mediastinoscopy and allows staging of mediastinal
lymphadenopathy.13
Ideally, diagnostic thoracoscopy and
surgical resection can be performed sequentially during the same period
of general anesthesia.14
Although curative resections can
be performed thoracoscopically,15
16
17
it is unlikely that
this technique will replace standard open surgical approaches for
lobectomy and pneumonectomy.
Chylothorax
Thoracoscopy has changed diagnostic and therapeutic approaches to
patients with chylothorax. Chylo-thorax is usually caused by trauma
or malignancy (primarily lymphoma). Thoracoscopic exploration
may precede or replace an open thoracotomy. If the torn thoracic duct
is visualized (having the patient drink heavy cream about 1 h
prior to the procedure may facilitate its detection), it can be clipped
or ligated endoscopically. Although survival is often limited in case
of chylothorax from lymphoma, talc pleurodesis may provide satisfactory
resolution of effusions and prevent deterioration of respiratory,
nutritional, and immunologic status.18
Lung Parenchymal Disease
Thoracoscopic lung biopsy helps establish the diagnosis of
diffuse or focal interstitial lung disease and pulmonary
infection.19
In addition, it provides tissue for
mineralogic studies of the pneumoconioses, and for diagnosis of
pulmonary infiltrates or peripheral nodular lesions of unknown
etiology. Specimens are usually obtained using an endoscopic stapling
device. Strict adherence to the classic principles of carcinologic
surgery should prevent parietal and pleural seeding of tumor cells
after thoracoscopic removal of lung nodules or masses.20
In many cases, patients can be discharged from the hospital in < 3
days with little morbidity. In one prospective study, morbidity rates
were only 1.5, 2.1, and 9.8%, respectively, in the elderly, patients
with poor lung function, and patients with depressed performance
status.21
Postoperative stay in an ICU is rarely
necessary. Thoracoscopy has prompted many practitioners to consider
lung biopsy earlier in the management algorithm of patients with
parenchymal disease of unclear origin, especially when bronchoscopic
lung biopsies have been nondiagnostic.22
It is noteworthy
that the role of thoracoscopic surgery in patients with metastatic
pulmonary nodules is unclear.23
Spontaneous and Secondary Pneumothorax
Thoracoscopy provides an excellent alternative to repeated
chest tube drainage in patients with recurrent or prolonged (usually
> 5 days) pneumothorax.24
Thoracoscopy allows definitive
treatment or inspection prior to performance of a lateral or axillary
thoracotomy.25
Thoracoscopic findings in patients with
spontaneous pneumothorax include normal appearance, pleural adhesions,
small blebs (< 2 cm) on the visceral pleural surface, and large
bullae (> 2 cm). Lesions can be removed using electrocautery, argon
plasma coagulation, or stapled lung resection, with results that are
similar to those obtained after open thoracotomy (although the
resultant pleurodesis may be somewhat less effective: recurrence rates
are reportedly 5 to 10% vs only 1 to 3% after open
thoracotomy).26
Talc insufflation for pleurodesis may also
be effective.27
Although most operators perform these
procedures using general anesthesia, thoracoscopic wedge
resection of blebs and bulla using local anesthesia has been
reported.28
Mediastinal Tumors
A thoracoscopic approach has been advocated for patients with
posterior and middle mediastinal tumors. Access can be difficult,
however, and it may be necessary to convert to open thoracotomy in
> 10% of instances.29
Postoperative hospitalization is
often less than after thoracotomy, but conversion should not be delayed
if there is bleeding, the lesion cannot be appropriately exposed, or
tumors are large.
Vasospastic Disease
Thoracoscopic sympathectomies are performed using either
electrocautery, dissection, or excision in patients with Raynaud’s
syndrome, causalgia, or essential hyperhydrosis.30
Exposure is usually through the anterior chest wall, and procedures can
be performed bilaterally at a single setting.31
Empyema
During the exudative and organizing phase of empyema,
thoracoscopic visualization allows debridement of fibrinous adhesions
and evacuation of loculated fluid.32
This procedure may
shorten the length of hospital stay and avoid
thoracotomy.33
The timing of thoracoscopic intervention is
critical, however, and should be considered when chest tube drainage is
unsatisfactory after 3 to 5 days. In one study, 82% of patients
treated thoracoscopically (mostly during the fibrinopurulent stage of
empyema) were treated effectively by thoracoscopic
debridement.34
The precise role for thoracoscopy instead
of chest tube drainage, instillation of fibrinolytic agents, rib
resection, or thoracotomy-decortication is still controversial.
Bullectomy and Lung Volume Reduction Surgery
Thoracoscopy is an accepted modality for lung volume
reduction surgery, with results that appear similar to those obtained
after median sternotomy.35
Endoscopic stapling can be
performed with or without buttressing staple lines. Results of
bilateral procedures appear better than unilateral procedures, and
costs are often less than with median sternotomy.36
Although improvements in pulmonary function, exercise performance, and
quality of life have been noted,37
FEV1 often deteriorates toward baseline prelung
resection values within 2 years. The role of thoracoscopy vs median
sternotomy for bilateral lung volume reduction surgery is currently
being evaluated in the National Emphysema Treatment Trial.
Chest Trauma
Thoracoscopy provides an effective and safe modality by
which to initially evaluate and often manage stable patients with blunt
or penetrating chest trauma.38
Diaphragmatic injury,
hemothorax, and lung parenchymal lacerations can be treated, although
difficulties associated with active bleeding, suboptimal single-lung
ventilation, or intense pleural inflammation should prompt conversion
to an open thoracotomy.
Cardiovascular Disease
Thoracoscopy can be used for ligation of a patent ductus
arteriosus,39
as well as to harvest internal thoracic
artery in patients undergoing coronary bypass grafting.40
A significant reduction in postoperative pain has been described,
attributed to the absence of rigorous chest retractions. It is likely
that many other applications for thoracoscopy-assisted cardiovascular
surgery will emerge.
Limitations and Future Directions
The thoracoscopic approach to a variety of diagnostic and therapeutic problems has few limitations other than a need to demonstrate safety and cost effectiveness compared with more conventional approaches. Procedure-related mortality is rare (0.24%, which is comparable to that of bronchoscopic biopsy) in experienced hands.41 Potential adverse events include bleeding, persistent pneumothorax, intercostal nerve and vessel injury, cardiac disturbances, complications related to anesthesia, respiratory failure, wound infections, and malignant seeding of the chest wall.42
Potential advantages of thoracoscopy over more conventional techniques include certainty of representative tissue for diagnosis, reduced requirements for postoperative analgesia, shorter hospital stays, and a shorter duration of chest tube drainage compared with thoracotomy.43 Thoracoscopists are studying ways to further eliminate the need for prolonged chest tube drainage after biopsy or pleurodesis,44 and to decrease procedure-related costs by employing reusable instruments. Additional studies are necessary to determine ideal settings for thoracoscopic intervention and to evaluate current perceptions regarding thoracoscopic practice. A recent survey of thoracic surgeons, for example, showed that most thought video-assisted thoracic surgery was an acceptable approach for the diagnosis of indeterminate pulmonary nodules, anterior and posterior mediastinal masses, clotted hemothorax, early empyema, and secondary pneumothorax, and for limited lung cancer treatment.45
Conclusion
Emerging technologies and an increased awareness of what can and cannot be done has prompted health-care providers to venture ever more aggressively into realms in which, previously, only open surgical procedures could be performed. Whether these procedures should be done instead of or in addition to conventional open procedures is being addressed by many investigators. In addition, thoracoscopy allows chest physicians to glance readily into the pleural space, enhancing their understanding of anatomic relationships and pleuropulmonary physiology. Now we must develop ideal venues for physician training and education,46 further improve safety profiles of technically challenging procedures, and effectively disseminate medical digital photography and videography on a global scale. The inclusion of thoracoscopy in this special section of CHEST is an important step in this direction.
Footnotes
Abbreviation: SVHS = Super VHS
References
This article has been cited by other articles:
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  M. G. Chrysanthidis and J. P. Janssen Autofluorescence videothoracoscopy in exudative pleural effusions: preliminary results Eur. Respir. J., December 1, 2005; 26(6): 989 - 992. [Abstract] [Full Text] [PDF]
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 N. Sawabata, A. Matsumura, A. Motohiro, Y. Osaka, K. Gennga, S. Fukai, and T. Mori Malignant minor pleural effusion detected on thoracotomy for patients with non-small cell lung cancer: is tumor resection beneficial for prognosis? Ann. Thorac. Surg., February 1, 2002; 73(2): 412 - 415. [Abstract] [Full Text] [PDF]
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 L. M. Seijo and D. H. Sterman Interventional Pulmonology N. Engl. J. Med., March 8, 2001; 344(10): 740 - 749. [Full Text] [PDF]
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