Pyng Lee, Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Outram Road, Singapore 169608. Email: email@example.com
Abstract: Pleuroscopy provides the pulmonologist with a unique opportunity to visualize the contents of the pleural space, perform biopsy of the parietal pleura under direct visual guidance, allow optimal chest tube placement and perform pleurodesis to prevent recurrent pleural effusion or pneumothorax in selected patients. We discuss the techniques, indications, contraindications and complications of pleuroscopy using rigid and semirigid instruments. In addition, the potential value and expanding role of pleuroscopy with semirigid instrumentation is debated.
Pleuroscopy allows for the evaluation of the pleural space by a trained non-surgeon1,2 and can be carried out in an endoscopy room, a minimally invasive surgical suite or in the operating room. The term pleuroscopy appears most appropriate when interventions are limited to diagnosing pleural pathology such as pleural effusions or pleural carcinomatosis. In fact, thoracoscopy, medical thoracoscopy and video-assisted thoracic surgery have been used interchangeably in the the published literature. The debate should not focus, therefore, on terminology, but rather on how nomenclature delineates the boundaries for a surgeon and a non-surgeon. We will use the term pleuroscopy in this review recognizing that any person who is trained in this procedure can execute it.
Pleuroscopy is usually performed in a sedated but spontaneously breathing, non-intubated patient. In recent years, there has been a trend towards greater utilization of neuroleptanalgesia (Propofol, B. Braun, Germany) and the laryngeal mask airway to enhance patient comfort. The operator should individualize preoperative anaesthesia by taking into careful consideration the patient's general condition and expectations as well as weighing the advantages and disadvantages of the various methods for pain control.
Since the first description of thoracoscopy by Jacobaeus in the 19th century,3 rigid endoscopic instruments such as stainless steel trocars and telescopes have been pivotal in the technique. However, with the recent introduction of the semirigid pleuroscope (model LTF-160, Olympus, Tokyo, Japan), similar in design and handling to the fiberoptic bronchoscope, pleuroscopy can now be performed in a fashion analogous to flexible bronchoscopy.
The last decade witnessed an overwhelming interest in pleuroscopy as a tool for pleural diseases.4 This is largely because 25% of cases seen in a pulmonologist's practice involve the pleura, and of which 20–25% of pleural effusions remain undiagnosed despite repeated thoracentesis and closed needle biopsy. In addition, practitioners are becoming more adept in procedures performed in a minimally invasive manner. It is perhaps this unrelenting quest for diagnosis coupled with improved endoscopic instrumentation that has led to a resurgence of interest in pleuroscopy.
Pleuroscopy is akin to chest tube insertion and can be carried out with a single site of entry using local anaesthesia. It is safe when performed by trained persons and we believe that with rapidly advancing technology, improved methods of anaesthesia and technology, pleuroscopy may replace conventional biopsy methods in the near future.5
Indications and contraindications
Patients with pleural disorders may require evacuation of pleural fluid, guided parietal pleural biopsy, lung biopsy or pleurodesis.6,7 Because pleuroscopy is performed under conscious sedation in a spontaneously breathing patient with partial or near-total lung collapse, these patients must not have allergy or hypersensitivity to the medications used, respiratory insufficiency requiring mechanical ventilation, intolerable hypoxaemia unrelated to pleural effusion, unstable cardiovascular status, bleeding diathesis or refractory cough.
The only absolute contraindication for pleuroscopy is the lack of pleural space due to adhesions, although technically, it can be overcome by enlarging the skin incision or digitally dissecting the lung from the chest wall.
A detailed history and physical examination are vital components of any preoperative evaluation. CXR, decubitus films, ultrasonography and CT scan aid in the selection of an appropriate entry site, while the patient's health and respiratory status is assessed by complete blood count, coagulation studies, electrocardiogram, arterial blood gas analysis, percutaneous oximetry and pulmonary function test.
In preparation for pleuroscopy in a patient with pleural effusion, approximately 200–300 mL of fluid is aspirated from the pleural cavity using a needle, angiocatheter, arrow thoracentesis catheter or Boutin pleural puncture needle (2 × 100 mm reusable trocar with side tap). Pneumothorax is induced by the opening of needle to air as the patient breathes until a stable equilibrium is reached. This allows the lung to collapse away from the chest wall and creates a space for trocar insertion. Conversely, the operator may choose to do the procedure directly as he or she enters a fluid-filled pleural space, or with the aid of ultrasonography.8
The patient is first placed in the lateral decubitus position with the affected side up and the arm raised above the head. Patient's vital parameters, ECG, blood pressure and oxygenation by means of pulse oximetry are monitored, which can be carried out by a nurse, anaesthesiologist or any other trained pleuroscopist. Local anaesthesia and conscious sedation with intravenous narcotic (fentanyl, demerol or morphine) and benzodiazepine (midazolam) are administered and titrated to patient comfort without compromising respiration. Others may prefer intravenous Propofol and assisted ventilation with, either laryngeal mask airway, or single lumen endotracheal tube for better control of analgesia.
Pleuroscopy is performed with single or double puncture technique.6,7 The single puncture, which involves making a 1–2-cm incision in the mid-axillary line between the 4th and 7th intercostal spaces of the chest wall, is commonly used for diagnostic pleuroscopy and talc poudrage, while the double punctures are required primarily to facilitate adhesiolysis, drainage of complex loculated fluid collections and lung biopsy. A chest tube or small bore-catheter is usually inserted at the end of the procedure and air is aspirated. The tube can be removed following complete lung re-expansion confirmed on CXR, and persistent air leak is rare if the lung has been carefully avoided during diagnostic pleuroscopy. The patient is monitored in a recovery area and can be discharged on the same day if clinically stable. However, if talc pleurodesis or lung biopsy is performed, the patient requires hospitalization for a period of monitoring and chest tube drainage.
Pleuroscopy performed by rigid endoscopic equipment requires a cold (xenon) light source, an endoscopic camera attached to the eye-piece of a telescope, video monitor and recorder (Fig. 1). Trocars used for pleuroscopy come in different sizes (diameter 5–13 mm) and are made of disposable plastic or reusable stainless steel. The single puncture technique uses a trocar measuring 5–10 mm, while double punctures require a combination of two trocars. On some occasions, these instruments may be passed through skin incisions without the use of trocars.
Rigid telescopes have different angles of vision for direct (0°) and oblique (30° or 50°) viewing. Although a 30° or 50° telescope provides a panoramic view of the pleural cavity, we prefer the straight-on 0° 4- or 7-mm telescope. Similarly, the 5-mm optical forceps or 5-mm coagulating tooth forceps are chosen for parietal pleural biopsy.
Smaller telescopes and instruments have also been used. Tassi and coworkers reported excellent views of the pleural space with a 3.3-mm telescope for a group of patients with small loculated pleural effusions that were inaccessible to standard-sized instruments. In their study, the diagnostic yield (>90%) obtained with a 3-mm biopsy forceps was also comparable with conventional forceps.9
Other accessories include sterile sheets and gowns, instruments that are commonly available in a chest tube insertion tray, such as needles, syringes, scalpel, sutures, forceps, needle holders and hemostats, antifog solution, local anaesthesia, talc atomizer, chest tube with inner stylet (9–32F) and negative suction drainage systems.
When using the novel semirigid pleuroscope, a single 1-cm skin incision, which accommodates a disposable 8-mm inner diameter flexible trocar, should suffice. The semirigid pleuroscope (model LTF 160 or 240, Olympus) consists of a handle that is similar to standard flexible bronchoscope and a shaft that measures 7 mm in outer diameter and 27 cm in length. The shaft is made up of two sections: a 22-cm proximal rigid portion and a 5-cm flexible distal end (Fig. 2a). The flexible tip is movable by a lever on the handle, which allows two way angulation capability of 160° up and 130° down. It also has a 2.8-mm working channel that accommodates biopsy forceps (Fig. 2b), needles and other accessories and is compatible with various electrosurgical and laser procedures. Moreover, the LTF 160 model allows autoclaving, thereby obviating important questions and issues related to asepsis. The other notable advantage of the semirigid pleuroscope over rigid instruments is that it interfaces easily with existing processors (CV-160, CLV-U40) and light sources (CV-240, EVIS-100 or 140, EVIS EXERA-145 or 160) made by the manufacturer for flexible bronchoscopy or GI endoscopy, which are available in most endoscopy units without additional costs.10,11
DIAGNOSTIC PLEUROSCOPY AND PLEURAL BIOPSY
Pleuroscopy using rigid or semirigid instruments allows visualization of the parietal, and visceral pleura. However, the posterior and mediastinal aspects of the hemithorax may be inaccessible if the lung is partially collapsed or when there are adhesions between the lung parenchyma and chest wall. This may necessitate a second entry point for the rigid telescope. In contrast, the semirigid pleuroscope, which combines the flexibility of the fiberoptic bronchoscope and the rigidity of conventional thoracoscope, overcomes the limited view by easy manoeuvrability of its nimble tip around the adhesions.10,11
Biopsy of the parietal pleura should be performed over a rib to avoid the neurovascular bundle. This can be achieved with the rigid optical or flexible forceps. The forceps are first used to probe the rib to feel the hard undersurface, followed by the grasping of the parietal pleura overlying it, and removing the pleura with a long tearing motion, rather than a ‘grab and pull’.
Specimens obtained with the rigid forceps are significantly larger than those with the Abram's or Cope needle. Biopsies with the semirigid pleuroscope are also small as they are limited by the size of the flexible forceps, which in turn depends on the diameter of the working channel.11 This technical hitch can, however, be overcome by taking multiple biopsies (range 5–10) of the abnormal areas as well as several ‘bites’ of the same area to obtain tissue of sufficient depth (Fig. 2c). Table 1 describes the type of patient suitable for rigid or semirigid pleuroscopy.
Table 1. Patient, radiological and endoscopic characteristics for rigid or semirigid pleuroscopy
Patient, radiological and endoscopic characteristics
Type of procedure and instrument
Preferred procedure and instrument of choice.
Diagnostic pleuroscopy for indeterminate, uncomplicated pleural effusion where suspicion of mesothelioma is not high
Semi-rigid pleuroscopy† (better tolerated) or with rigid telescopes under local anaesthesia
Rigid instruments or converting to thoracotomy for decortication
Pneumothorax with bulla or blebs
Rigid instruments (VATS) for staple bullectomy
Mortality from conventional pleuroscopy using rigid instruments ranges between 0.09 and 0.24%12,13 and is comparable to that associated with bronchoscopic transbronchial lung biopsy. The complications are listed in Table 2.
Table 2. Complications of pleuroscopy
Prolonged air leak
Seeding of chest wall from mesothelioma
Complications with the semirigid pleuroscope, in contrast, are rare. In fact, it has been shown to be very safe when performed by pulmonologists trained in conventional pleuroscopy. No morbidity nor mortality was observed during its evaluation by two separate centres, one in North America10 and the other in the United Kingdom,11 on a total of 60 procedures performed in 58 patients. This observation is also shared by the authors’ experience of 50 cases over 12 months (unpubl. data). However, many studies of complication rates involve procedures performed by specialists and may not reflect circumstances with less experienced physicians. The need for adequate and satisfactory training cannot be overemphasized.
CLINICAL APPLICATIONS FOR PLEUROSCOPY
Pleural effusion of unknown aetiology
The first step towards investigating pleural effusion of unknown aetiology is still thoracentesis. Pleural fluid is analyzed for chemistry, microbiology and cytology. Cytological examination of pleural fluid is diagnostic in 62% of patients with metastatic pleural involvement,14 and fewer than 20% with mesothelioma.15 Although repeated large volume thoracentesis and closed needle biopsy increase the yield to 74% for malignant effusion, 20–25% of cases remain undiagnosed. If neoplasm is strongly suspected, pleuroscopic exploration and biopsy are recommended as the diagnostic sensitivity of the procedure approaches 90–100%.16
More than half of exudative effusions are due to malignancy.16 Pleural fluid cytology is the simplest definitive method, however, its diagnostic yield depends on the extent of disease and the nature of the primary malignancy.17 Closed needle biopsy may be successful in 50% of metastatic pleural malignancies,18 however, it is of little value for tumours confined to the diaphragmatic, visceral or mediastinal pleura. Therefore, pleuroscopy in undiagnosed pleural effusion aids in: (i) establishing the diagnosis of malignancy in greater than 85%19,20 if polypoid lesions, localized tumoural masses (Fig. 3), thickened pleura or ‘candle wax drops’ are observed; (ii) guided biopsy of these pleural abnormalities for histological confirmation and hormone receptor analysis;21 (iii) removal of any adhesions to improve drainage of fluid; (iv) assessment of lung expandability or presence of trapped lung during fluid aspiration without additional imaging studies; (v) pleurodesis with sclerosing agent to prevent recurrence in selected cases (Fig. 4); and (vi) optimal chest tube placement under visual guidance. Moreover, we are of the opinion that with increasing application of pleuroscopy, it not only enhances the practitioner's understanding of pleuro-pulmonary anatomy, but also allows for clinico-radiographical and pathological correlation that may impact on future management decisions.
Cancer-related pleural effusions occur as a result of direct tumour invasion, tumour emboli to the visceral pleura with secondary seeding of the parietal pleura, haematogenous spread or lymphatic involvement.16 It is rare to find resectable lung cancer in the setting of pleural effusion despite negative cytological examination.22 Pleuroscopy therefore establishes operative eligibility by determining whether the pleural effusion is para-malignant or due to metastases. If pleural metastases are found, making the cancer inoperable, talc poudrage performed at the same sitting has been shown to be more effective in preventing recurrence than intrapleural instillation of sclerosant.23
The average survival of a patient diagnosed with malignant mesothelioma is 6–18 months with death resulting from respiratory failure.24 Over the last 30 years, the incidence of mesothelioma has been increasing steadily and the 1940s male birth cohort is particularly affected where the disease is estimated to be accountable for almost 1% of all deaths in Europe over the next 35 years.25
Malignant mesothelioma is suspected in a patient with a history of asbestos exposure and characteristic radiographical findings of a pleural effusion without contralateral mediastinal shift. Diagnosis by pleural fluid cytology and closed needle biopsy is difficult,15 which has prompted some physicians to advocate open biopsy by mini or lateral thoracotomy to obtain specimens of sufficient size and quantity for immunohistochemical stains and electron microscopy.26 Today, conventional pleuroscopy is favoured over thoracotomy as, not only are the pleural specimens obtained with the 5- or 7-mm rigid forceps comparable with open biopsies,27 but it allows staging to be achieved in a minimally invasive manner.
Pleuroscopy with semirigid instruments, on the other hand, raises valid concerns about adequacy of pleural biopsies obtained with the small flexible forceps. As these issues are still unresolved at the time of writing, pending future studies, we would recommend the use of rigid 5-mm optical forceps in cases where mesothelioma is suspected.
Mesothelioma is notorious for seeding biopsy and chest tube sites, thus pleuroscopy and chest tube incisions should be placed so that if subsequent therapeutic resection is performed, these sites can be easily excised, or prophylactically irradiated.28 Estimates have suggested that only 1–5% of patients are suitable for curative surgery.29 In the majority who usually have advanced disease, even at first presentation, aggressive palliation of dyspnoea via pleuroscopic guided drainage and talc pleurodesis, improved pain control and prophylactic irradiation of incision sites have resulted in effective symptom control.30
Tuberculous pleural effusion
The average diagnostic yield from closed needle biopsy in tuberculous (TB) pleural effusion is 69%, although a wide range of 28–88% has been reported.31 In a prospective study of 100 TB effusions in Germany, immediate histological diagnosis was established by pleuroscopy in 94% compared with 38% by closed needle biopsy. Positive yield from histology and bacteriological cultures was also found to be higher with pleuroscopic guided biopsies than with closed needle biopsy and pleural fluid combined.32 These results were reproduced in a study conducted in a country with high TB prevalence where diagnostic yield from pleuroscopic guided biopsy was 98% compared with 80% by the Abram's needle.33 Many experts therefore recommend that if TB pleuritis is strongly suspected in a patient residing in a high TB prevalent area, thoracentesis and closed needle biopsy should suffice, and pleuroscopy reserved for special circumstances where lysis of adhesions is indicated for more effective drainage of loculated effusions or when larger quantities of tissue are required for culture in suspected drug-resistant cases (Fig. 5).
Empyema and complicated parapneumonic effusions
Pleuroscopy is useful in the management of empyema34,35 and should be performed early in the course of disease where fluid can be easily evacuated and lysis of thin fibrinopurulent adhesions to facilitate pleural drainage and allow lung expandability. Chest tubes can be placed under direct guidance, even in a complicated pleural space with adhesions, which may aid drainage and hasten clinical resolution of symptoms. However, in some cases, the finding of a thick pleural peel, trapped lung or a complicated multiloculated pleural space during pleuroscopy, may prompt immediate referral for early decortication.
In spontaneous pneumothorax, pleuroscopy can reveal blebs and bullae, allow coagulation of blebs as well as prevent recurrence by methods such as pleural abrasion or talc pleurodesis.23 Detection of blebs and bullae may be higher with video assisted thoracoscopic surgery (VATS) or thoracotomy than with pleuroscopy,36 but several investigators have independently shown that specific treatment of these bullae associated with primary or secondary spontaneous pneumothoraces has not improved the outcome of pleurodesis.37,38 This is particularly relevant for a selected group of patients with advanced lung disease and comorbidity, who are at higher risk for general anaesthesia, VATS or thoracotomy. In these instances, air leaks can be repaired and recurrent pneumothoraces effectively prevented by thoracoscopic talc poudrage.38 For recurrent primary spontaneous pneumothorax, VATS with staple bullectomy and parietal pleural abrasion or pleurectomy is preferred.
Pleuroscopy is effective in the evaluation of pleural and pulmonary diseases when routine cytology and closed needle biopsy fail. In many institutions where facilities for pleuroscopy are available, it replaces second attempt thoracentesis and closed needle biopsy for patients with exudative effusions of unclear aetiology. Pleuroscopy also offers the non-surgeon the ability to intervene therapeutically; to breakdown loculations in early empyemas and complicated parapneumonic effusions, and perform pleurodesis for recurrent malignant effusions and pneumothoraces. The semirigid pleuroscope is similar in design and handling to the flexible bronchoscope and is compatible with standard light source and video processor available in most bronchoscopy suites. This technological advance will ensure that pleuroscopy continues to enjoy an expanded interest, both as a diagnostic and therapeutic tool.
Although pleuroscopy is generally safe, it is an invasive procedure. To minimize procedure-related complications, pulmonologists intent on performing pleuroscopy should not only receive specific training in the techniques and instrumentation but be cognisant of appropriate patient selection, the indications and contraindications of pleuroscopy. Moreover, a consultative collaboration between the pleuroscopist, primary care physician, chest radiologist and thoracic surgeon assures that patients undergoing these procedures are fully and adequately assessed.
The arrival of the semirigid pleuroscope will revolutionize the practice of pulmonary medicine in the same way that the flexible bronchoscope did four decades ago. Current debate should not focus on the time-honoured controversy of where to perform and who should perform pleuroscopy but rather when to use conventional rigid and semirigid instruments for different clinical scenarios.
Pleuroscopy will play a greater role in the future as more practitioners acquire the skill. The technique has been made simpler with the advent of the semirigid pleuroscope and the cost benefits of its compatibility with standard equipment found in most endoscopy suites. Moreover, continual development in equipment design along the lines of semirigid instrumentation may facilitate more effective aspiration of fluid, greater mobilization of the lung and guided chest tube placement in future. Ideally, improvement in the design of the flexible biopsy forceps will occur, allowing the operator to obtain larger and potentially more representative tissue samples, especially where mesothelioma is suspected or when densely infiltrated pleura is encountered.
The semirigid pleuroscope is a significant invention in the history of minimally invasive pleural procedures. As pleuroscopic technology and techniques continue to evolve, it will certainly pave new inroads into stimulating and directing novel research and education in the future.