Thoracoscopy




Introduction


Biopsy procedures play an essential role in the diagnostic evaluation of patients with respiratory diseases. Most of the basic techniques we use today were mainly developed and refined during the 20th century. Recently, significant advances in endoscopic technology have provided sophisticated endoscopic instruments and endoscopic telescopes with extremely high optical resolution and small diameters. In addition, developments in anesthesiology offer a wide range of alternatives, from procedures performed under local anesthesia to selective double-lumen intubation under general anesthesia.


As with all medical procedures, the risk-benefit ratio of more invasive methods has to be considered for each individual patient, weighing the risk for morbidity and mortality against the benefit of obtaining an early diagnosis to guide correct therapy. Usually the more invasive procedures are used if simpler, less invasive methods have failed, if the latter are not very promising for obtaining a reliable diagnosis, or if additional therapeutic options can be combined with the diagnostic approach.


This chapter reviews these more invasive thoracoscopic procedures as performed by pulmonologists. Other biopsy methods, such as bronchoscopic biopsies, thoracentesis, needle biopsy of lung lesions, and closed-needle biopsy of the pleura, are described in other chapters.




Thoracoscopy (Pleuroscopy/Medical Thoracoscopy)


Historical Development


Thoracoscopy was introduced together with laparoscopy in 1910 by Hans-Christian Jacobaeus, who at that time worked as an internist in Stockholm, Sweden. He published his first experiences in a paper entitled “On the Possibility to Use Cystoscopy in the Examination of Serous Cavities.” It was recently reported that, as early as 1866, F.R. Cruise in Ireland had possibly been the first to perform a thoracoscopy, examining the pleural space of a girl with empyema through a pleurocutaneous fistula that had developed after spontaneous pleural drainage. Jacobaeus, in his pioneering paper, mentions two cases of pleuritis exudativa (tuberculous pleurisy), in which he studied the pleural surfaces after replacing the fluid with air. Although not able to get a clear impression of the pleural changes, he was confident that the method would be successful in the future and might eventually yield prognostic information. Jacobaeus himself initiated the therapeutic application of thoracoscopy for lysis of pleural adhesions by means of thoracocautery to facilitate pneumothorax treatment of tuberculosis (“Jacobaeus operation”). During the ensuing 40 years, his technique of using a single entry site for the thoracoscope and another for the electrocautery device under local anesthesia was applied worldwide for this specific therapeutic purpose, until antibiotic therapy of tuberculosis was introduced and made the procedure obsolete. Between 1950 and 1960, a generation of chest physicians familiar with the therapeutic application of thoracoscopy began to use the technique for biopsy diagnosis of pleural and even pulmonary disease. Today, thoracoscopy is considered as an integral part of interventional pulmonology.


At the same time, the excellent results of laparoscopic surgery and the tremendous advances in endoscopic technology stimulated many thoracic surgeons almost simultaneously in Europe and the United States to develop minimally invasive techniques, which were termed “therapeutic” or “surgical thoracoscopy , ” as well as video-controlled or videothoracoscopic surgery, or video-assisted thoracic surgery (VATS).


To clarify the difference between the two methods, the term medical thoracoscopy was introduced. This is performed using the Jacobaeus technique under local anesthesia or conscious sedation, via a single or two sites of entry, by the pulmonary physician in an endoscopy suite using nondisposable rigid instruments. Its main indications are the diagnosis and treatment of recurrent pleural exudative effusions and the treatment of spontaneous pneumothorax. However, because the term thoracoscopy is used for both the medical and the surgical procedures, a degree of uncertainty has arisen, which may lead to unnecessary surgical interventions for what are, in fact, medical indications. Recently the old term pleuroscopy has been reintroduced mainly for thoracoscopy with the semirigid (semiflexible) instrument called a pleuroscope.


Finally, in some countries, interventional pulmonologists have broadened their field of expertise to include more elaborate interventions (e.g., sympathectomy, splanchnicectomy, treatment of empyema) and to perform thoracoscopy in the operating theater, under total intravenous anesthesia and spontaneous ventilation (with a laryngeal mask or simple endotracheal tube protecting the airway) or mechanical ventilation.


In fact, the terms thoracoscopy, medical thoracoscopy, and pleuroscopy are used interchangeably in the literature. To avoid confusion, in this chapter we will use the term thoracoscopy for the procedure performed by the pulmonologist, and consequently also the terms thoracoscopist and thoracoscope . For the thoracoscopic procedure performed by a surgeon, we will use the term VATS .


In Europe thoracoscopy is part of the training program of pulmonary medicine, and it is becoming more popular in the United States. According to a national survey in 1994, thoracoscopy was used frequently by 5% of all pulmonary physicians. Although newer data are not yet available, the interest in the technique seems to be increasing. However, training is lagging: in an American College of Chest Physicians’ survey of U.S. pulmonary/critical care fellowship programs in 2002–2003, only 12% of the directors stated that thoracoscopy was offered in their programs. In the United Kingdom, where thoracoscopy has been underutilized compared with the rest of Europe, there is also growing interest. The British Thoracic Society published a guideline on thoracoscopy (using local anesthetic) in 2010. In this guideline, three levels of competence in thoracoscopy are defined, of which level 1 includes basic diagnostic and therapeutic techniques and level 2 the more advanced techniques, whereas level 3 covers all VATS techniques (e.g., lung resection) and is the province of the thoracic surgeon.


Meanwhile, the technique has been introduced successfully in many Asian countries and in other parts of the world, particularly with the introduction of the semirigid (semiflexible) thoracoscope, called a pleuroscope.


Techniques


Thoracoscopy is an invasive technique that should be used to obtain a diagnosis when other, simpler methods are nondiagnostic (in case of pleural exudates) or to achieve pleurodesis (in case of recurrent pleural effusion or pneumothorax). As with all technical procedures, there is a learning curve before full competence is achieved. Appropriate training is therefore mandatory. The technique of insertion by means of a trocar is actually very similar to that of chest tube insertion. Once the pleuroscope is in the pleural space, the thoracoscopist can visualize and obtain a biopsy specimen from all areas of the pleural cavity, including the chest wall, diaphragm, mediastinum, and lung under direct visual control. When indicated, talc poudrage can be performed. In general, thoracoscopy is easier to learn than flexible bronchoscopy if sufficient expertise in thoracentesis and chest tube placement has already been gained.


There are two different techniques of diagnostic and therapeutic thoracoscopy, as performed by the pulmonary physician ( ). In the first method, as first described by Jacobaeus for diagnostic purposes, a single entry site is usually produced with a 7- or 9-mm trocar for a thoracoscope with a working channel for accessory instruments and optical biopsy forceps; for this technique, local anesthesia is usually employed. This approach can be modified for use of a semirigid thoracoscope (also called pleuroscope). In the other technique, as used by Jacobaeus for lysis of adhesions, two entry sites are used: 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. For this technique, conscious sedation or general anesthesia is preferred.


Equipment


Rigid instruments are still in use, as they were from the beginning. Compared with the rigid thoracoscopes, flexible bronchoscopes or other flexible endoscopes have several disadvantages, mainly less adequate orientation within the pleural cavity and small channels that limit the size of biopsy forceps, which may result in inadequate biopsy specimens. A recently modified semirigid pleuroscope with a flexible tip has become an attractive alternative. As mentioned, the single-entry-site technique is usually performed via a 7- or 9-mm diameter trocar and a cannula with valve. Trocars are also available with diameters of 5 and 3.75 mm for performing thoracoscopy in children. Optical devices exist with various fields of view (0, 30, and 90 degrees) ( Fig. 24-1 ). Recently mini-thoracoscopy has been introduced, with the use of a rigid optical telescope of 3 mm and a trocar with a diameter of 4 mm. The indication for minithoracoscopy is for the evaluation of a small pleural effusion or the presence of a narrow intercostal space. A second port of entry is necessary to obtain biopsy specimens. In infants, smaller rigid equipment (3.5 mm), also used for minithoracoscopy, or instruments similar to those used in rigid bronchoscopy are employed. Biopsy forceps with the feature of viewing straight ahead to the biopsy site as well as accessory instruments such as puncture needle, cautery electrode, probe, combined suction, cautery cannula with valves, and various biopsy forceps and scissors are available. For talc pleurodesis, a talc atomizer is used.




Figure 24-1


Instruments for thoracoscopy.

A, Trocar and cannula with valve. B, Single-incision thoracoscope (9 mm diameter). C, Biopsy forceps with straight optics. D, Magnified view of optical device and forceps in the thoracoscope shaft ready for biopsy.

(Redrawn from Loddenkemper R: Thoracoscopy—state of the art. Eur Respir J 11:213–221, 1998.)


The two-entry-site technique uses a 7-mm trocar for the first site of entry for appropriate telescopes and forceps and similar accessory instruments. For the second site of entry, a 5-mm trocar is used for insertion of instruments designed for its smaller bore, including a loop for dividing adhesions and a double-lumen insufflator.


As stated earlier, the semirigid (semiflexible) pleuroscope, was developed recently. The design, including the handle, is similar to that of a standard flexible bronchoscope; however, the proximal 22 cm is stiff and the distal 5 cm is bendable with an angulation of 160 and 130 degrees ( Fig. 24-2 ). The outer diameter of the shaft is 7 mm, and a working channel of a diameter of 2.8 mm allows the use of standard instruments available for flexible bronchoscopy. The semirigid pleuroscope has several advantages. The skills involved in operating the instrument are already familiar to the practicing bronchoscopist. Because the shaft is rigid, it can be moved like the rigid thoracoscope without losing the orientation, and it is compatible with the video processors and light sources of the same manufacturer. Finally, the flexible tip permits easier visualization of the entire pleural cavity and permits a homogeneous distribution of talc on all surfaces. Compared with rigid thoracoscopic instruments, the disadvantages of the flexible pleuroscope are the costs, the vulnerability of the scope, and the smaller biopsy specimens, although its diagnostic yield in pleural disease has been shown to be comparable with that of the conventional rigid thoracoscope. In addition, the flexible forceps used with the pleuroscope may not have the mechanical strength to obtain pleural biopsy specimens of sufficient depth, which may reduce the diagnostic yield in mesothelioma. This technical problem can be overcome by the use of a diathermic knife, which is also useful for the cutting of pleuropulmonary adhesions.




Figure 24-2


The semirigid (semiflexible) pleuroscope (Olympus Corporation).

Control section allows handling as with the flexible bronchoscope.

(Copyright Olympus SE & Co. KG.)


The procedure suite should be equipped with monopolar and, if possible, bipolar electrocoagulation as well as equipment for resuscitation and assisted ventilation, electrocardiography, and blood pressure monitoring, and a defibrillator, an oxygen source, and vacuum generators.


Thoracoscopy can be performed in the operating room or in an environment dedicated to invasive procedures (see ). The personnel required to perform thoracoscopy include an endoscopy nurse (or an endoscopy assistant) to assist with the instrumentation, an additional assistant outside the sterile field to bring necessary equipment, and the physician performing the thoracoscopy. Ideally an additional person sits at the patient’s head and monitors his or her overall condition. In an emergency, thoracoscopy can be performed with only a physician and a nurse, but this is less efficient and prolongs the procedure. Medical thoracoscopy can also be performed safely in an entirely outpatient setting.


Indications


Thoracoscopy today is primarily a diagnostic procedure, but it can also be applied for therapeutic purposes ( Table 24-1 ). Thoracoscopy is mainly used for diagnosis of exudates of unknown cause, for staging of diffuse malignant mesothelioma or lung cancer, and for treatment by talc pleurodesis of malignant or other recurrent effusions. Thoracoscopy is also useful for evaluation and possible treatment of spontaneous pneumothorax and empyema. For those familiar with the technique, thoracoscopy is also indicated for diagnostic biopsies from the diaphragm, lung, mediastinum, and pericardium and for more elaborate procedures. As mentioned earlier, there is an overlap of indications between thoracoscopy and VATS (see later discussion and Table 24-1 ). In addition, thoracoscopy offers a remarkable tool for research as a gold standard in the study of pleural effusions.



Table 24-1

Indications for Thoracoscopy (Medical Thoracoscopy) versus VATS (Surgical Thoracoscopy)

































































Thoracoscopy Thoracoscopy or VATS (Gray Area) VATS
PLEURAL EFFUSIONS SPONTANEOUS PNEUMOTHORAX LUNG PROCEDURES



  • Pleural effusions of unknown cause




  • Staging




  • Lung biopsy




  • Staging of lung cancer




  • Pleurodesis by talc poudrage




  • Lobectomy




  • Staging of diffuse malignant mesothelioma



  • Pleurodesis by talc poudrage




  • Lung volume reduction surgery

EMPYEMA (STAGE I/II) PLEURAL PROCEDURES



  • Drainage




  • Pleurectomy (pneumothorax)

Diffuse pulmonary diseases


  • Drainage/decortication (empyema stage III)




  • Biopsy

ESOPHAGEAL PROCEDURES
LOCALIZED LESIONS


  • Excision of cyst, benign tumors




  • Chest wall, diaphragm




  • Esophagectomy




  • Sympathectomy




  • Antireflux procedures




  • Splanchnicectomy

MEDIASTINAL PROCEDURES



  • Resection of mediastinal mass




  • Thoracic lymphadenectomy




  • Thoracic duct ligation




  • Pericardial window




  • Sympathectomy


VATS, video-assisted thoracic surgery.


The diagnosis of pleural effusions is the main and oldest indication for thoracoscopy, as described by Jacobaeus himself in his earliest articles. However, even in the therapeutic era, publications from many countries emphasized the diagnostic value of thoracoscopy in spontaneous pneumothorax, focal pulmonary disease, diseases of the chest wall, mediastinal tumors, diseases of the heart and great vessels, and thoracic trauma. Later, these indications were expanded to include performing biopsies for localized and diffuse lung diseases. Today, the use of thoracoscopy for diagnosis of lung diseases has decreased owing to the improvements in less invasive pulmonary biopsy techniques such as flexible bronchoscopic biopsy and computed tomography (CT)-guided biopsy.


In the past, therapeutic thoracoscopy was used extensively for collapse treatment of tuberculosis to sever adhesions that prevented a complete artificial pneumothorax. This indication disappeared after the successful introduction of chemotherapy for tuberculosis. Today, the main indication for therapeutic thoracoscopy is talc poudrage in malignant or other chronic and recurrent pleural effusions. The first report on talcage was published in 1935, and in 1963 it was first used for treating recurrent effusions. Since then, talc poudrage performed during thoracoscopy for pleurodesis in malignant pleural effusions has been widely applied, especially in Europe. Talc pleurodesis via thoracoscopy has several advantages over pleurodesis via a thoracostomy tube: simultaneous drainage of pleural fluid, visualization of the visceral pleura to ensure that the lung is not encased by pleural thickening or tumor that could prevent reexpansion ( ), and guidance of chest tube placement. In addition, talc pleurodesis can also be used to prevent recurrent pneumothorax.


Other indications for therapeutic thoracoscopy are the drainage of empyema or dorsal sympathectomy in hyperhidrosis patients. Anecdotal reports describe its use for removal of foreign bodies, for removal of benign tumors, and for production of pericardial fenestrations.


Contraindications


Contraindications to thoracoscopy are few and rarely absolute. The main limitation is the size of the free pleural space, which must be at least 6 to 10 cm in width. If extensive adhesions prevent the lung from collapsing away from the chest wall, thoracoscopy can still be performed (extended thoracoscopy), but this requires special skill and should not be undertaken without appropriate training.


Several factors may make it necessary to postpone thoracoscopy but are rarely prohibitive; these include a persistent cough, hypoxemia, hypocoagulability (prolonged international normalized ratio or platelet count <40,000 to 60,000/µL), and cardiac abnormalities. Hypercarbia indicative of respiratory failure may prove to be an absolute contraindication, except in patients with a tension pneumothorax or massive pleural effusion, in whom it can be anticipated that thoracoscopy would provide therapeutic benefit in addition to a possible diagnosis. Under these conditions, premedication should be administered judiciously to minimize respiratory center depression. Even in very ill patients on a ventilator, diagnostic thoracoscopy has been carried out without significant complications.


Contraindications for pulmonary biopsy are suspicion of arteriovenous pulmonary aneurysm, vascular tumors, hydatid cysts, and a stiff fibrotic lung. Relative contraindications for pulmonary biopsy would include previous systemic steroid or immunosuppressive therapy because, under these circumstances, bronchopleural fistulas resulting from lung biopsy may heal poorly.


The thoracoscopist must consider the risk-benefit ratio in each case. Thoracoscopy should be performed only after careful evaluation aimed at answering specific questions.


Complications


Thoracoscopy is a safe and effective modality in the diagnosis and treatment of several pleuropulmonary diseases if certain standard criteria are fulfilled. In the most thorough review, there was only 1 death among 8000 cases, for a mortality rate of 0.01%. In another series reviewing 4300 cases, the mortality rate was 0.09%. The reported mortality rate of thoracoscopy is thus roughly equivalent to or less than that of transbronchial biopsies. In another report of 817 thoracoscopy procedures using conscious sedation and local anesthesia, the complications were persistent air leak of more than 7 days’ duration in 2%, subcutaneous emphysema in 2%, and postoperative fever in 16%. The major complication rate in a series of 102 patients was 1.9% and included ventricular tachycardia responding to resuscitation, subcutaneous emphysema, and persistent air leak. The minor complication rate was 7.5%, including transient air leak, fever, and minor bleeding at a biopsy site. Another large series including 360 patients reported morbidities of fever in 9.8%, empyema in 2.5%, pulmonary infection in 0.8%, and malignant invasion of the scar in 0.3%. Major uncontrollable bleeding requiring thoracotomy was not reported in any of these large series and appears to be extremely rare. Many complications such as benign arrhythmias, low-grade hypotension, and hypoxemia can be prevented by administration of oxygen. In case of persistent bleeding, electrocoagulation may become necessary.


Reexpansion pulmonary edema from the removal of large pleural effusions is infrequent, perhaps because immediate equilibration of the pleural pressure is provided by direct entrance of air through the cannula into the pleural space. Bronchopleural fistulas may follow lung biopsies; if the lungs are stiff, a fistula may require longer to heal than the usual 3- to 5-day period of chest tube drainage with applied pleural suction. Local site infection is uncommon, and empyema has been reported only very rarely. In cases of mesothelioma the late complication of tumor growth at the site of entry has been observed after thoracoscopy and also after thoracentesis or closed-needle biopsy. Radiation therapy 10 to 12 days after thoracoscopy has been reported to prevent this late complication, although the standard use of prophylactic radiation therapy in these cases is controversial. After talc poudrage, any postprocedure fever, as a nonspecific inflammatory reaction, and pain can be treated symptomatically. In conclusion, the overall mortality rate with thoracoscopy is extremely low. Morbidity, which is mainly due to benign postprocedural fever, is also minimal. Thoracoscopy in the hands of the appropriately trained pulmonologist is safe.


Patient Preparation


Before thoracoscopy, radiologic evaluation should routinely include a posteroanterior and a lateral chest radiograph. Ultrasonography for localization of the pleural fluid and for diagnosis of potential fibrinous membranes or adhesions in the pleural space is helpful (see Chapter 20 ). In a British observational study, thoracic ultrasonography localized a safe site for thoracoscopy when not clinically apparent in 11 out of 80 cases (14%) and detected unexpected septations in 7 (9%). According to the guidelines of the British Thoracic Society on pleural procedures and ultrasonography, thoracic ultrasonography is strongly recommended for all pleural procedures to localize the site of pleural fluid. A CT scan is not mandatory but can be helpful to localize abnormalities such as loculated empyema or localized lesions (tumors) of the chest wall or diaphragm.


Evaluation of the patient’s respiratory status requires, at a minimum, arterial or capillary blood gas analysis. An electrocardiogram should be obtained to exclude recent myocardial infarction or significant arrhythmia. The clinical laboratory will provide the coagulation parameters, serum electrolyte levels, and blood glucose level as well as blood group typing, platelet count, results of liver function studies, and serum creatinine level.


The planned technique, the management of possible postoperative complications, and the expected diagnostic or therapeutic results should be explained to the patient. It is only then that the patient can truly provide informed consent.


The site of introduction of the thoracoscope depends in part on the location of abnormalities to access and the location of potentially hazardous areas to avoid. Thoracoscopy is usually performed with the patient in the lateral decubitus position with the intended procedural site facing upward. A pillow is placed under the patient’s flank, causing the spine to flex laterally and widening the intercostal spaces at the procedural site.


Access to the Pleural Space


Because it is impossible to perform the procedure if the pleural cavity is completely obliterated, a sufficiently large pleural space is an essential prerequisite, allowing the introduction of the trocar and thoracoscope without injuring the lung or other organs (see ).


The simplest access is available in the setting of a preexisting complete pneumothorax or large pleural effusion, in which the trocar can be introduced directly into the pleural space without risk for injuring the lung. In the setting of a small or moderate-size pleural effusion, a needle puncture should be performed at the level of greatest opacification/dullness or, ideally, under ultrasonographic or fluoroscopic guidance. When pleural fluid is aspirated, the syringe is removed from the needle, and air enters the pleural space either spontaneously or after the patient takes a few deep breaths. The entry of air causes the lung to collapse away from the chest wall and creates a pleural space for safe trocar insertion. Alternatively, if one is certain that the needle is well positioned in the pleural fluid (e.g., not in the lung), air can be injected into the pleural space by means of a syringe. Most often, a few milliliters of air is sufficient to create a good separation of the lung from the chest wall. Greater safety is provided under ultrasonographic guidance, which allows the operator to localize the pleural effusion and to exclude thick septations/adhesions, which may prevent a sufficient collapse of the lung and thus may cause possible complications such as bleeding and injury to the lung, diaphragm, and other thoracic structures when introducing the trocar at the site of the septations/adhesions. Another option is fluoroscopy “on the table,” which can show the air-fluid level caused after injection of air, as well as the presence of any adhesions.


If neither effusion nor pneumothorax is present, an artificial pneumothorax must be created either by the blunt dissection technique using the finger or by the technique of pneumothorax induction. The blunt dissection technique (extended thoracoscopy) involves gentle dissection of the pleural adhesions with a finger to advance the thoracoscope into the pleural space. Some operators introduce carbon dioxide, instead of air, to maximize absorption rates in the unlikely event of air embolism. If so, the pneumothorax should be induced immediately before undertaking thoracoscopy, because the pneumothorax will be absorbed rapidly. Some thoracoscopists induce the pneumothorax the day before the procedure, allowing more time to obtain pressure measurements and to determine if the pleural space is patent, as indicated by a fluctuation of pressure with breathing between −15 and −5 cm H 2 O (1 cm H 2 O ≅ 1 mbar).


However, some experienced teams regularly perform thoracoscopy without any form of image-guided induction of a pneumothorax. In one series of more than 700 thoracoscopies conducted without preprocedural imaging of the entry site, induction of a pneumothorax was impossible in only 10 patients, due to extensive adhesions. In this series, no major complications such as bleeding were observed.


Anesthesia


Thoracoscopy by the single-entry-site technique is usually done under local anesthesia with premedication, together with an antianxiolytic, a narcotic, or both (e.g., midazolam and hydrocodone). If necessary, additional pain medication should be given during the procedure, as required. With this conscious sedation, an anesthetist is not needed. Exceptions are rare idiosyncratic or allergic sensitivities to typical anesthetics, very anxious or uncooperative patients, including children, and severe hypercarbia. An excellent alternative today is sedation by propofol with or without premedication ; however, the use of propofol for moderate sedation is not approved in some countries, including the United States, without the supervision of an anesthesiologist. General anesthesia with intratracheal intubation and ventilation is used in some centers, as it is for VATS, but is not generally necessary for thoracoscopy.


Monitoring devices such as a cardiac monitor, oxygen saturation monitor, and automatic blood pressure monitor are applied. Some advocate the simultaneous measurement of cutaneous or exhaled carbon dioxide tension, because sedation may lead to significant hypoventilation. An intravenous line is maintained, both for intravenous sedation and for possible resuscitation medications.


Thoracoscopic Technique


The site of introduction of the thoracoscope should be chosen to access the location of presumed abnormalities and to avoid potentially hazardous areas such as the midanterior line, where one finds the internal mammary artery, the axillary region with the lateral thoracic artery, and the infraclavicular region with the subclavian artery (see ). The region of the diaphragm is unsuitable, not only because adhesions are frequent but also because the liver or spleen may be injured. For general applications the trocar is introduced in the lateral thoracic region between the midaxillary and the anterior axillary line in the 4th to 7th intercostal space (“safety triangle”); for pleural effusions, in the 6th or 7th intercostal space; and for pneumothorax, in the 4th intercostal space. Following preparation with a surgical disinfectant and local anesthesia using 1% or 2% lidocaine, a small skin incision is made, and the trocar is advanced with a fairly forceful corkscrew motion until the detectable resistance of the internal thoracic fascia has been overcome. The cannula of the trocar should lie at least 0.5 cm within the pleural space. Pleural effusions should be removed by using a suction tube that does not occlude the cannula, so that air may rapidly enter the pleural space to equalize pressures. After complete removal of the effusion, or in cases without effusion, the optical device is introduced through the cannula, and the pleural space is then inspected (see ) ( Fig. 24-3 ).




Figure 24-3


CT representation of pleuroscopy in the right thoracic cavity with the patient in the left lateral decubitus position.

Visualization of the chest wall, pleura, diaphragm, lung, and anterior (and part of posterior) mediastinum is possible.

(From Loddenkemper R: Thoracoscopy—state of the art. Eur Respir J 11:213–221, 1998.)


The pleural space can be inspected directly through the thoracoscope or indirectly by viewing the image on a screen via videothoracoscopy, the standard procedure today. The advantages of videothoracoscopy over direct thoracoscopy are multiple: The view is better when projected on a screen, the other participants of the procedure (fellow, nurse, anesthesiologist) can watch the thoracoscopy, which is also important for teaching purposes, and indirect viewing provides greater sterility.


Anatomic relationships and intrathoracic structures are usually well recognized ( ). Biopsies of the pleura and, if needed, of the lungs, can be performed easily and safely by means of the lung biopsy forceps ( ). In the presence of undiagnosed pleural effusions, biopsy specimens should be taken from macroscopic lesions at the anterior chest wall, the diaphragm, and the posterior chest wall for histologic evaluation and, if there is suspicion of tuberculosis, for mycobacterial culture. If no macroscopic abnormalities are visible, several biopsy specimens should be taken from different sites of the parietal pleura. Biopsy specimens from the lung are not taken routinely because of the risk for creating a fistula but may be necessary when the abnormalities are seen only on the lung surface. The likelihood of creating a bronchopleural fistula can be reduced by the use of an electrocautery biopsy forceps. In cases of inflammatory pleural exudates or when several therapeutic thoracenteses have already been performed, fibrinous membranes or adhesions may be present that hinder examination. If so, these can be severed by using a blunt forceps or by cutting with electrocautery.


Although a single site of entry is generally sufficient, a second site may be useful for biopsies or to coagulate. A second port of entry is mandatory to introduce a biopsy forceps in case of mini-thoracoscopy, in which the scope is too small to accommodate a forceps. The position of the second site of entry can be determined by viewing through the 50-degree scope while depressing the possible entry site with the index finger. It is sometimes helpful to insert a needle through the same site while viewing its precise location through the thoracoscope. After administration of a local anesthetic, a 5-mm incision is made and the 5-mm trocar is inserted directly. Its cannula will accommodate many instruments designed for its smaller bore.


Talc Pleurodesis


Talc poudrage is the most widely reported method of talc instillation into the pleural space. It is mainly used for pleurodesis in malignant or recurrent pleural effusions but is also used in persistent or recurrent spontaneous pneumothorax. Thoracoscopic talc pleurodesis can be performed under local anesthesia but generally requires additional pain medication.


Before the procedure it is important to confirm that the lung can completely expand because contact of the lung with the chest wall will be necessary for a successful pleurodesis. Failure to expand fully may indicate a trapped lung caused by thickening of the visceral pleura (which can be confirmed at thoracoscopy) or a main-stem bronchial occlusion by tumor. If the chest radiographs fail to show a contralateral mediastinal shift in the presence of a large pleural effusion, an endobronchial obstruction should be suspected and, if possible, removed by bronchoscopy before the thoracoscopy.


During the procedure, in cases of pleural effusion it is important to remove all pleural fluid before spraying with talc. Complete collapse of the lung is desirable, because it permits wide and uniform distribution of the talc.


The optimal dose of talc for poudrage is not known, but usually a dose of approximately 5 g is recommended for malignant or recurrent effusions, whereas for pneumothorax patients 2 g is usually sufficient. The pleural cavity should be inspected during talc insufflation to ensure that the talc is uniformly distributed ( ). For this purpose one can use a thoracoscope with an angled optical device and a flexible suction catheter that is connected to a small bottle containing talc and to a pneumatic atomizer introduced through the working channel of either the thoracoscope ( Fig. 24-4 ) or the semirigid pleuroscope.




Figure 24-4


The flexible catheter, connected to a small bottle containing talc and to a pneumatic atomizer (manual insufflator), is introduced through the working channel of the rigid thoracoscope.


After talc poudrage a 10- to 24-French chest tube should always be inserted and pointed toward the posterior costovertebral gutter in patients with effusions or toward the apex in patients with pneumothorax. It is questionable if suction is necessary. If suction is applied, the use of high-volume, low-pressure systems is recommended, with a gradual increment in pressure to about −20 cm H 2 O. Following the procedure, chest tube removal has been recommended when the daily amount of fluid production is less than 150 mL, but there is little evidence to support this practice. One report suggests that the chest tube can be removed within 24 hours without regard to daily fluid production. A potential advantage of talc poudrage via thoracoscopy compared with slurry delivered via chest tubes is the more even distribution of talc over the whole pleural surface. In three head-to-head studies comparing talc poudrage with talc slurry instillation, talc poudrage was at least equally, and in some studies significantly more, effective, than talc slurry; slurry has never been shown to be superior to poudrage. In patients undergoing thoracoscopy, talc poudrage should therefore be the preferred method. In patients with a poor Karnofsky index, or when thoracoscopy is refused or impossible, talc slurry represents a valid alternative.


Talc is inexpensive and highly effective. Its most common short-term adverse effects include fever and pain. Cardiovascular complications such as arrhythmias, cardiac arrest, chest pain, myocardial infarction, and hypertension have been noted ; whether these complications result from the procedures or are related to talc per se has not been determined. Acute respiratory distress syndrome, acute pneumonitis, and respiratory failure have also been reported after talc poudrage and slurry, especially in the United States. The development of respiratory failure is most likely due to the dose and especially to smaller particle sizes of talc, which can distribute via the pleural stomata (which are the openings to the lymphatics) to the lung. Ferrer and associates demonstrated that the particle size of the talc used in the United States is significantly smaller than the French talc that is used in Europe (10th percentile diameter 2.4 to 3.1 µm in the United States versus 10.5 µm for French talc). In a review it was demonstrated that a small particle size of talc plays a key role in the development of complications after talc pleurodesis via the pleural lymphatics to the rest of the body. The use of size-calibrated, larger-size talc appears to be absolutely safe in the treatment of recurrent pleural effusions and spontaneous pneumothorax. Unfortunately, the large-particle size-calibrated French talc has not yet been approved for use in the United States.


Results


Pleural Effusions


Even after extensive diagnostic workup of the pleural fluid, the cause of a number of pleural effusions may remain undetermined. Blind needle biopsies may establish the diagnosis in some additional cases, particularly in tuberculous pleurisy. In a series by Boutin and colleagues of 1000 consecutive patients with pleural effusion, 215 cases remained undiagnosed after repeated pleural fluid analysis and performance of pleural biopsies. This is in agreement with the results of several other authors who, without the use of thoracoscopy, report that at least 20% to 25% of pleural effusions remain undiagnosed, although this certainly depends strongly on the particular patient populations. Because of the higher diagnostic yield and ability to induce pleurodesis in a single setting, it has been estimated in a theoretical cost analysis in the United Kingdom that medical thoracoscopy may save considerable costs in the evaluation of unexplained pleural effusions compared with other tests, including image-guided pleural biopsy.


Several studies have tried to determine the diagnostic accuracy of thoracoscopy in the setting of undiagnosed pleural effusion, but the results vary widely, with a range of 60% to 90%. Closer evaluation of the study designs reveals that the duration of follow-up was occasionally short and frequently not mentioned at all. One well-designed study of thoracoscopy in 102 patients reported by Menzies and Charbonneau, with follow-up periods between 1 and 2 years, found a sensitivity of 91%, a specificity of 100%, accuracy of 96%, and a negative predictive value of 93%. Boutin and colleagues reported a false-negative rate of 15% within 1 year of follow-up. In a retrospective study of 709 patients who underwent thoracoscopy for diagnosis of unexplained exudative effusions, Janssen and coworkers also found a 15% false-negative rate in a long-term follow-up (minimum, 24 months) of 208 patients with initial negative results; the overall sensitivity of thoracoscopy was 91%, the specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 92%. Of note, even thoracotomy can miss the diagnosis. In a study of the results of thoracotomy in patients with pleural effusion of undetermined cause, even after a pathologic diagnosis of a benign pleural process, 25% of patients were diagnosed with a malignancy. The diagnoses most often missed were malignant pleural mesothelioma and lymphoma (mesothelioma in 10 and lymphoma in 4 out of 31 cases, and lymphoma in 6 and mesothelioma in 4 of 13 cases ). Autofluorescence videothoracoscopy may help in the future to avoid some of the false-negative results.


Because of its high diagnostic accuracy, diagnostic thoracoscopy is an excellent option in cases of exudates in which the cause remains undetermined after pleural fluid analysis. The procedure allows fast and more definite biopsy diagnosis, including a high yield for tuberculosis cultures, and determination of hormone receptors in some malignancies. Furthermore, staging in lung cancer and diffuse mesothelioma is possible. The exclusion of an underlying malignancy or of tuberculosis is provided with high probability. Surgery, including surgical thoracoscopy, not only is more invasive and expensive but also does not produce better results than thoracoscopy and should therefore be reserved for very selected cases.


Malignant Pleural Effusions


Diagnosis.


Malignant pleural effusions are today the leading diagnostic and therapeutic indication for thoracoscopy ( Figs. 24-5 and 24-6 ). In a prospective comparison of different diagnostic tests, the diagnostic yield of nonsurgical biopsy methods in malignant pleural effusions was studied simultaneously in 208 patients, including 116 metastatic pleural effusions (from 28 breast cancers, 30 cancers of various other organs, and 58 cancers of undetermined origin); 29 cancers of the lung; 58 diffuse malignant mesotheliomas; and 5 malignant lymphomas. The diagnostic yield of pleural fluid cytologic examination was 62%, of closed pleural biopsy was 44%, and of thoracoscopy was 95%. The sensitivity of thoracoscopy was higher than that of cytologic examination and closed pleural biopsy combined (95% vs. 74%, P < 0.001). The combined methods were diagnostic in 97% of malignant pleural effusions ( Fig. 24-7 ). In 6 of the 208 cases (2.9%), an underlying neoplasm was suspected at thoracoscopy but confirmed only by thoracotomy or autopsy. Similar results have been reported by a number of other investigators.


Jul 21, 2019 | Posted by in CARDIOLOGY | Comments Off on Thoracoscopy
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