 Lesson 12, Volume 15—Medical Thoracoscopy
By Robert Loddenkemper, MD, FCCP
Effective December 31, 2004, PCCU Volume 15 is available for review purposes only. CME credit for this volume is no longer being offered. Objectives
- To describe the technical aspects of medical thoracoscopy.
- To identify the indications for medical thoracoscopy.
- To describe the advantages of medical thoracoscopy in the diagnosis
of pleural effusions.
- To describe the role of medical thoracoscopy in the staging
of lung cancer and diffuse malignant mesothelioma.
- To describe the value of medical thoracoscopy in spontaneous
pneumothorax.
- To identify talc poudrage as the best option for conservative
pleurodesis.
Key words
diffuse malignant mesothelioma; empyema; pleural
effusions; pneumothorax; talc pleurodesis; tuberculous pleurisy
Abbreviations
TB = tuberculosis; VATS = video-assisted thoracic
surgery
When compared with surgical
thoracoscopy, or video-assisted thoracic surgery (VATS), medical
thoracoscopy has the advantage in that it can be performed under
local anesthesia or conscious sedation, in an endoscopy suite,
and using nondisposable rigid instruments. Thus, it is considerably
less invasive and less expensive than VATS.
Thoracoscopy was introduced by Jacobaeus, an internist
in Stockholm, in 1910, primarily to diagnose pleural effusions.1 However,
during the ensuing 40 years, thoracoscopy was applied on a worldwide
scale almost exclusively for lysis of pleural adhesions by means
of thoracocautery ("Jacobaeus’s operation") to facilitate
pneumothorax treatment of tuberculosis (TB).2
With the advent of anti-TB chemotherapy, a generation
of physicians who were already familiar with the therapeutic application
of thoracoscopy began to use this technique on a wider basis, mainly
in Europe, for evaluating many pleuropulmonary diseases. Detailed
descriptions of pleural disease, with emphasis on TB and malignant
pleural effusions, appeared in the literature and the diagnostic
potential of thoracoscopy was again verified.3,4
With technical improvements and the trend towards
less invasive procedures, thoracoscopy was rediscovered by thoracic
surgeons at the beginning of the last decade and termed "surgical" thoracoscopy,
which is actually VATS.5 Interestingly, this revival
has also supported the introduction of "medical" thoracoscopy into
the scope of respiratory practice, particularly in the United States
where, according to a national survey in 1994, more than 5% of
all pulmonologists were using medical thoracoscopy.6 In
Europe, thoracoscopy is intrinsic in the training program of pneumology.7
Techniques
Medical thoracoscopy is an invasive technique that
should be used only when other, simpler procedures are not helpful.
As with all technical procedures, there is a learning curve before
full competence is achieved. Therefore, appropriate training is
mandatory. The technique is similar to chest-tube insertion by
means of a trocar, the difference being that, in addition, the
pleural cavity can be visualized and biopsy specimens can be taken
from all areas of the pleural cavity including the chest wall,
diaphragm, mediastinum, and lung. Thus, the term thoracoscopy should
be preferred to "pleuroscopy," which is occasionally used instead.8
An absolute prerequisite for thoracoscopy is the
presence of an adequate pleural space, which should be at least
6 to 10 cm in width. If not present, a pneumothorax is induced
under fluoroscopic or radiographic/sonographic control, immediately
or the day before thoracoscopy.
The main advantage of medical thoracoscopy over VATS
is that the examination can be performed under local anesthesia
or conscious sedation after premedication and without the support
of an anesthesiologist. Furthermore, medical thoracoscopy is less
expensive as it may be performed safely with nondisposable instruments
in an endoscopy suite.
The different techniques of diagnostic and therapeutic
thoracoscopy, as performed by the pneumologist, are described in
detail elsewhere.3,4,9 Essentially, one method consists
of a single entry with a 9-mm thoracoscope with a working channel
for accessory instruments, optical biopsy forceps, and local anesthesia.
The other involves two entries, one with a 7-mm trocar for the
examination telescope and the other with a 5-mm trocar for accessory
instruments including the biopsy forceps, and conscious sedation
or general anesthesia.
Electrocoagulation should be available for cauterization
of adhesions and blebs or in cases of bleeding after biopsy. For
pleurodesis of effusions, 8 to 10 mL of sterile, dry, asbestos-free
talc is insufflated through a rigid or flexible suction catheter
with a pneumatic atomizer. For pneumothorax, 2 to 3 mL of talc
is sufficient. Immediate suction through the chest tube is always
applied following the procedure.
Flexible bronchoscopes have also been used but have
several disadvantages when combined with the rigid thoracoscopes, ie, less
optimal orientation within the pleural cavity and smaller biopsies.
Currently under development are special semiflexible instruments
with a rigid shaft and a flexible tip.
Medical thoracoscopy can be performed either under
direct vision through the endoscopic optics or indirectly by video
transmission (which allows demonstration to assistants and others
as well as appropriate documentation).
Prevention of Complications
Medical thoracoscopy is safe if contraindications
are observed and standard criteria are fulfilled.8 An
obliterated pleural space is an absolute contraindication. Relative
contraindications include bleeding disorders, hypoxemia, unstable
cardiovascular status, and persistent, uncontrolled cough.
During the procedure, cardiorespiratory function
should be monitored by ECG, blood pressure measurement, and continuous
oximetry. Complications such as benign cardiac arrhythmias, blood
pressure instability, or hypoxemia can virtually be prevented by
administration of oxygen.
The reported mortality rates are very low (< 0.01%).
Several liters of fluid can be removed during thoracoscopy with
little risk of pulmonary edema, because immediate equilibration
of pressures is provided by direct entrance of air through the
cannula into the pleural space. If lung re-expansion appears to
be diminished, ony low-pressure suction should be applied through
the pleural drainage tube, which is always placed at the conclusion
of the thoracoscopy. Following lung biopsy, a bronchopleural fistula
may occur, requiring a longer period of suction than the usual
3 to 5 days, particularly in patients with poorly compliant lungs.
After talc poudrage, fever may occur. Local site infection is uncommon
and empyema is rare.
In cases of mesothelioma, radiotherapy may be performed
10 to 12 days after thoracoscopy to prevent the late complications
of tumor growing at the entry sites.10
Indications
Medical thoracoscopy is primarily a diagnostic procedure,
but it can be used for therapeutic purposes. The most common indications
for medical thoracoscopy include evaluation of the unknown exudative
effusion, staging of diffuse malignant mesothelioma or lung cancer,
and treatment by talc pleurodesis of malignant or other recurrent
effusions or empyema. Local treatment of spontaneous pneumothorax
is also a prime indication. For those familiar with the technique,
other diagnostic indications include biopsies of the diaphragm,
lung, mediastinum, and pericardium. In addition, medical thoracoscopy
offers a remarkable tool for research as a gold standard in the
study of pleural effusions.8
Pleural Effusions
Even after extensive diagnostic evaluation of a patient
with a pleural effusion, the etiology often remains unclear.11,12 Blind
needle biopsies may establish the diagnosis in some cases, particularly
in tuberculous pleurisy.13,14
If facilities for the procedure are available, medical
thoracoscopy should be performed in patients with undiagnosed effusions
because of its high diagnostic sensitivity in malignant and tuberculous
pleural effusions. The tissue obtained will usually provide a higher
yield of the positive TB cultures and determination of hormone
receptors in breast cancer.
The application of medical thoracoscopy allows the
simultaneous insufflation of talc powder, which currently offers
the best results in pleurodesis. Further therapeutic advantages
include complete fluid removal and evaluation of the re-expansion
potential of the lung. Fibrinous loculations in TB and empyema
can be easily removed, thus creating a single pleural cavity that
can be treated more effectively.
Malignant Pleural Effusions
Malignant pleural effusions are the leading diagnostic
and therapeutic indication for medical thoracoscopy.15 In
a prospective intrapatient comparison in 208 patients, the diagnostic
yield of medical thoracoscopy was 95% vs 62% for pleural fluid
cytology and 44% for percutaneous needle biopsy. Medical thoracoscopy
showed a significantly higher sensitivity (p < 0.001) than needle
biopsy plus cytology, which were positive in 74%. All methods taken
together were diagnostic in 97% of cases of malignant pleural effusions.
These results have been confirmed by others.8
In our experience, there is no difference in the
yield for the different types of malignant pleural effusions: 96%
in 67 cases of lung carcinoma, 96% in 154 cases with extrathoracic
primary tumors, and 92% in 66 cases with diffuse malignant mesothelioma.
The reasons for false-negative thoracoscopy results
include insufficient and nonrepresentative biopsies, the experience
of the thoracoscopist, and the presence of adhesions, which deny
access to neoplastic tissue.16
Medical thoracoscopy is helpful in the staging of
lung cancer, diffuse malignant mesothelioma, and metastatic cancer.
In the case of concomitant pleural effusion in lung cancer that
otherwise appears resectable, medical thoracoscopy is indicated
as a staging procedure to distinguish malignant from paramalignant
effusion. The latter condition would allow for resection of the
tumor; however, in 80 to 95% of the patients, the effusion is due
to tumor spread and surgical cure is not possible. Thus, medical
thoracoscopy can help avoid unnecessary thoracotomy.8
In diffuse malignant mesothelioma, medical thoracoscopy
provides an earlier diagnosis, more precise histologic classification
due to a larger, more representative biopsy, and more accurate
staging.17,18 This may have important therapeutic implications,
as better responses to local immunotherapy or chemotherapy in stages
I and II have been observed. Thoracoscopy is also helpful in the
diagnosis of benign asbestos-related pleural effusion, which is
a diagnosis of exclusion.
Fibrohyaline or calcified, thick, pearly white pleural
plaques indicate probable asbestos exposure. Thoracoscopic lung
biopsies and even biopsies from certain lesions on the parietal
pleura may demonstrate high concentrations of asbestos fibers,
providing further support to the diagnosis of asbestos disease.8
In metastatic pleural effusions, biopsies of the
visceral and diaphragmatic pleura are only possible under direct
vision. Because the chest wall pleura is often not involved (in
approximately 30% of cases) in early stages, it is not possible
in these cases to provide a diagnosis by blind needle biopsy.19 With
the large size of biopsy specimens obtained by thoracoscopy, it
may be easier for the pathologist to suggest the origin of the
tumor. In metastatic breast cancer, tissue can be obtained for
determination of hormone receptors. Even with lymphomas, the diagnostic
yield as well as the morphologic classification is improved.8
Local Treatment of Pleural Malignancies
The main therapeutic option offered by medical thoracoscopy
is the prevention of recurrent effusion with pleurodesis. Under
direct visual control, 8 to 10 mL of asbestos-free, sterilized
talc is insufflated into the pleural space so that the powder is
equally distributed on the parietal and visceral pleura. Talc poudrage
is probably the most effective, conservative option for pleurodesis.4,20
Tuberculous Pleurisy
TB now causes < 10% of all effusions seen in Western
Europe and the United States. Although the yield of blind needle
biopsy is higher than in pleural malignancies, the diagnostic accuracy
of thoracoscopy is greater because the pathologist is provided
with multiple, selected biopsy specimens, and because the cultural
proof of tubercle bacilli is more frequently positive. In a prospective
intrapatient comparison, the histologic diagnosis of 100 patients
with TB was established by thoracoscopy in 94%, compared with only
38% with needle biopsy, allowing antituberculous chemotherapy to
be started earlier. The combined yield of pleural histology and
culture was 99% for medical thoracoscopy, 51% for needle biopsy,
and 61% when combined with fluid culture. The percentage of positive
TB cultures was twice as high from thoracoscopic biopsy specimens,
including cultures from fibrinous membranes (78%), compared with
the percentage in pleural effusions and needle biopsy specimens
combined (39%), allowing bacteriologic confirmation of the diagnosis
drug susceptibility testing. In 5 of the 78 positive cases (6.4%),
resistance against one or multiple antituberculous drugs was found,
which influenced therapy and prognosis.8
In another prospective study of 40 patients from
South Africa, thoracoscopy had a diagnostic yield of 98%, in comparison
with an 80% diagnostic yield with Abrams' needle biopsies.21 This
led to the conclusion that in areas with a high prevalence of TB,
Abrams’ needle biopsy (three biopsy specimens were obtained
and each examined histologically and microbiologically) can contribute
significantly to the diagnosis. However, in a further study on
the effect of corticosteroids in the treatment of tuberculous pleurisy,
the same authors found that the initial complete drainage of the
effusion, performed during thoracoscopy, was associated with greater
symptomatic improvement than any subsequent therapy.22
Other Pleural Effusions
When effusions are neither malignant nor tuberculous,
thoracoscopy may provide macroscopic clues to their etiology, eg, in
rheumatoid effusions, effusions following pancreatitis, hepatic
hydrothorax, extension of disease from the abdominal cavity, or
trauma. Although history, pleural fluid analysis, and physical
and other examinations are usually diagnostic in the above examples,
thoracoscopy may be indicated in the problematic cases. When pleural
effusions are secondary to underlying lung diseases such as pulmonary
infarction or pneumonia, the diagnosis can frequently be made based
on macroscopic examination and confirmed microscopically via lung
biopsy. As mentioned, thoracoscopy is well suited for the diagnosis
of benign asbestos-related pleural effusions, which by definition
present a diagnosis of exclusion.23
In other pleural effusions, when the origin is unknown,
the main diagnostic value of thoracoscopy lies in its ability to
exclude malignant and tuberculous disease. By means of thoracoscopy,
the proportion of so-called idiopathic pleural effusions usually
decreases to < 10%, whereas studies in which thoracoscopy was
not used report failure to obtain a diagnosis in > 20% of cases.
These figures depend on the selection of patients and the definition
of "idiopathic."8
In selected cases of recurrent pleural effusions
of nonmalignant etiology, including chylothorax, pleurodesis may
be induced by applying talc poudrage during medical thoracoscopy.20
Empyema
Medical thoracoscopy can also be useful in the management
of early empyema.24 In cases with multiple loculations,
it is possible to open these spaces, remove the fibrinopurulent
membranes by forceps, and create a single cavity that can be drained
and irrigated more successfully. This treatment should be instituted
early in the course of empyema, before adhesions become too fibrous
and adherent. Thus, if placement of a chest tube is indicated and
if the facilities are available, medical thoracoscopy should be
performed at the time of chest-tube insertion. Overall, medical
thoracoscopy is a procedure similar to chest-tube placement but
enables the creation of a single pleural cavity, allowing better
local treatment. Prospective studies on this use of medical thoracoscopy
have not yet been done.
VATS is a more invasive procedure because general
anesthesia and selective double-lumen intubation are necessary.
The former should be avoided, if possible, in very ill patients.
Surgery, however, is indicated in the late organizational stage
with dense and extensive adhesions.
Spontaneous Pneumothorax
In spontaneous pneumothorax, medical thoracoscopy
can be used for diagnostic and therapeutic purposes if the skills
and facilities for this technique are available.3,4,9 In
particular, if a chest tube is introduced by a trocar technique,
it is easy to use an optic to visually inspect the lung and pleural
cavity before inserting the chest tube through this cannula. On
inspection during medical thoracoscopy, the underlying lesions
can be directly assessed according to the classification of Vanderschueren:
stage I with an endoscopically normal lung; stage II with pleuropulmonary
adhesions; stage III with small bullae and blebs (< 2 cm in
diameter); and stage IV with numerous large bullae (> 2 cm in
diameter). Although the detection rates of blebs and bullae are
higher in series with VATS or thoracotomy, larger bullae, blebs,
or fistulae will likely be detected during medical thoracoscopy.25
Medical thoracoscopy offers the possibility of combining
chest drainage with coagulation of blebs and bullae as well as
pleurodesis by talc poudrage. Talc poudrage achieves the best conservative
treatment results with recurrence rates of < 10%. In stage IV
with numerous large bullae, VATS or thoracotomy usually should
be performed. Talc poudrage and/or coagulation of bullae are performed
only in patients in whom surgery is contraindicated because of
respiratory insufficiency secondary to severe bronchitis or other
advanced pulmonary disease.26
In our view, medical thoracoscopy is justified in
all patients with spontaneous pneumothorax when tube drainage is
indicated, because it provides several advantages: precise assessment
of underlying lesions under direct visual control; choice of best
treatment measures (conservative or surgical); direct treatment
by coagulation of blebs and bullae; severing of adhesions; administration
of talc poudrage; and selection of the best location for chest-tube
placement.
Summary
The main diagnostic and therapeutic indications for
medical thoracoscopy are for the diagnosis of pleural effusions
and the treatment of pneumothorax. Because of its high diagnostic
accuracy—approaching almost 100% in malignant and tuberculous
pleural effusions—thoracoscopy should be used when pleural
fluid analysis and needle biopsy are nondiagnostic. In addition,
medical thoracoscopy provides staging for lung cancer and diffuse
malignant mesothelioma. It can also be used effectively in the
early management of empyema. Talc poudrage, an excellent method
for pleurodesis, can also be performed with medical thoracoscopy.
In spontaneous pneumothorax, thoracoscopy allows staging, thereby
facilitating treatment decisions, as well as permitting coagulation
of bullae and blebs and talc poudrage for effective pleurodesis.
Medical thoracoscopy is a safe procedure that is
easier to learn than flexible bronchoscopy. Based on its high diagnostic
and therapeutic efficacy, thoracoscopy should be applied increasingly
in the management of the aforementioned pulmonary diseases. Medical
thoracoscopy can be performed under local anesthesia or conscious
sedation, in an endoscopy suite, using nondisposable rigid instruments.
Thus, it is considerably less invasive and expensive than surgical
thoracoscopy/VATS.
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