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Thoracoscopy is a minimally invasive procedure that allows visualization of the pleural space and intrathoracic structures. It enables the taking of pleural biopsies under direct vision, therapeutic drainage of effusions and pleurodesis in one sitting.1-4 Pleural effusion is a common medical problem and undiagnosed pleural effusions remain a diagnostic challenge for pulmonologists. The primary pleural fluid assessment includes thoracentesis and percutaneous needle biopsy. If malignancy is suspected, only 60% of malignant effusions can be diagnosed by cytological examination.1 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.2 It is also highly sensitive in the diagnosis of tuberculosis.3 Wyser et al5 found that the initial complete drainage of the effusion, performed during thoracoscopy, was associated with greater symptomatic improvement than any subsequent therapy. Therefore, thoracoscopy can serve as an excellent diagnostic procedure in patients with undiagnosed pleural effusions. Despite these well-known facts, thoracoscopy is not frequently performed by pulmonologists in the world.6-8 In the past, it has required the use of a specialized rigid endoscopic equipment as well as camera and light source. Besides the expense of the additional instruments, the rigid thoracoscope is an unfamiliar tool for most physicians.
Recently, a semi-rigid thoracoscope with a bidirectional tip was developed, which is similar in design to the standard flexible bronchoscope and is compatible with the commonly used endoscopic video system.7,9 Chest physicians are quite familiar with performance skills, and less equipment needs to be purchased. Thoracoscopy can now be performed in a fashion analogous to flexible bronchoscopy
Since July 2005, medical thoracoscopy with the above mentioned semi-rigid thoracoscope has been performed in our department. Fifty patients with undiagnosed pleural effusions, including 23 patients who received routine examination from July 2004 to June 2005 and 27 patients who underwent medical thoracoscopy during July 2005 and June 2006 were recruited in this retrospective study, and the differences in diagnostic sensitivity, costs related to pleural fluid examination, and complications were compared directly between the two investigated groups.
METHODS
Patients and inclusion criteria
Fifty patients admitted to our respiratory department for pleural effusions during July 2004 and June 2006 were studied. From July 2005 to June 2006, semi-rigid thoracoscopy was performed on 30 patients. Three patients without fluid were excluded. Thus, a total of 27 patients undergoing thoracoscopy were evaluated (Group 1). From July 2004 to June 2005, 23 patients who had undiagnosed pleural effusions were included in this study (Group 2). According to the inclusion criteria, all patients had undergone routine examinations for pleural effusion, including medical history, clinical examination, chest radiography, sputum smears for acid fast bacilli and cytology, thoracentesis for biochemistry, cytology and microbiology, with no established diagnosis in ten days after admission. Blind percutaneous pleural biopsies were not included in the routine examinations in the study for the poor diagnostic yield in China,10 in spite of some studies showing the good diagnostic rate of 75% for tuberculosis and 57% for carcinoma.1 All patients with an exudative pleural effusion according to Light's criteria were included. After review of the detailed medical records and screening through telephone, patients without complete records or medical thoracoscopy were excluded. Fifty patients with undiagnosed pleural effusions (23 had routine examination from July 2004 to June 2005 and 27 obtained medical thoracoscopy) were recruited.
Diagnostic criteria
Pleural effusion with neoplasic cells in pleural fluid or neoplasic infiltration in a pleural tissue biopsy sample was considered neoplasic. Parapneumonic effusion was defined as pulmonary infiltrates with pleural effusions that disappear after the treatment of antibiotics and show no evidence of malignancy or tuberculosis during the follow-up. The diagnoses of tuberculous pleurisy were based on the presence of caseating granulomas or epithelioid cell granuloma with no evidence of other pulmonary granuloma diseases such as sarcoidosis, fungal infection, etc. The following variables for a comparative analysis were recorded: sex, age, diagnoses, fluid characteristics, times of thoracentesis, costs related to pleural fluid examination, and complications.
Thoracoscopic procedures
In our study, a semi-rigid thoracoscope (model LTF-240, Olympus, Tokyo, Japan) was used. The tip is flexible with an upward angulation of 130° and a downward angulation of 130°, which are similar to those of the flexible fibreoptic bronchoscope. The total length of the instrument is 52 cm, with the insertion portion being 27 cm. The external diameter of the insertion portion is 7 mm and the inner working channel is 2.8 mm. It accommodates the biopsy forceps and other instruments for further treatments. It is compatible with the EVIS 240 video processors and light sources (Olympus).
All procedures were done under local anesthesia with spontaneous breathing by a chest physician in the operating room (Beijing Chaoyang Hospital, Beijing, China) equipped with patient monitoring devices. Written informed consents were obtained. A single puncture technique was used and the lateral decubitus position was employed, with the involved side upward. After skin sterilization, blunt dissection was made to enter the pleural space. A flexible trocar（8.0-mm diameter) was inserted on the midaxillary line into the sixth to eighth intercostal areas under the B-ultrasound. Then the thoracoscope was inserted, and the pleural cavity was inspected after all fluid was drained completely. Biopsies were performed under direct visual control in all suspect areas, systematically in several parts of the parietal pleura for cytological and pathological examination. In addition，biopsy of the parietal pleura should be performed over a rib to avoid the neurovascular bundle. Adhesions between the two pleural leaves were removed when necessary. A 24F chest drain was inserted for drainage. Chest radiographs were routinely obtained after the procedure and re-check until the removal of the chest tube.
Statistical analysis
Statistical analysis was made by the Statistical Product for Social Sciences (SPSS version 11.5). Data were expressed as mean ± standard deviation (SD), proportions, or percent. Continuous data between the two groups were compared using Student's t test. The categorical data were compared using the chi-square test or Fisher's exact test. A P value less than 0.05 was considered statistically significant.
RESULTS
Clinical characteristics
The characteristics of these patients are summarized in Table 1. No significant differences were found between the two groups.
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Table 1. Characteristics of the study population |
Final diagnoses
Patients in group 2 underwent 97 times of thoracentesis and only 1 patient had closed pleural biopsy twice. Patients diagnosed with tuberculous pleurisy in group 2 were probable cases, and they were confirmed by effective response to anti-tuberculosis chemotherapy and high lymphocyte counts in pleural fluid. The patients in group 1 were subjected to thoracoscopy. The results of diagnostic procedures are summarized in Table 2. Laboratory examination for patients with parapneumonic effusion showed prominant polymorphonuclear cells and an acute episode of the disease. After antibiotic therapy, their pleural effusion resolved. The diagnostic efficiency of thoracoscopy was 93% (25/27). Only 21% of the patients were confirmed by routine examinations. Twelve patients with tuberculous pleurisy in group 2 were probable cases.
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Table 2. Final diagnosis based on routine examination or thoracoscopy (n) |
Significant difference was observed in final diagnosis of pleural effusions in patients who received routine examinations compared with those who received thoracoscopy (P=0.000). Semi-rigid thoracoscope was easy to use, and fluid was easily suctioned. The image quality was nice as well (Figure a–g).
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Figure. Images recorded using the flexi-rigid thoracoscope. (a) The pleural cavity with pleural fluid, (b) adenocarcinoma, (c) squamous-cell carcinoma, (d) lymphoma, (e) metastatic suprarenal epithelioma, (f) tuberculous pleurisy, and (g) tuberculous pleurisy with adhesions. |
Examination cost for pleural effusion
The cost of pleural effusion test was calculated by taking into account the payment for each related procedure, including the costs of thoracetesis, B-ultrasound investigation, B-ultrasound guided pleural aspiration and thoracoscopy. Ultrasound guided pleural aspiration is usually considered a safe and accurate method for obtaining fluid if the effusion is small or loculated. The comparative results of cost-effectiveness in this study are shown in Table 3, and there was no significant difference between the two groups (P=0.114).
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Table 3. Comparison of cost-effectiveness between group 1( thoracoscopy) and group 2 (routine examination) |
Complications
Twenty-three patients underwent 97 times of thoracentesis and 2 patients received pleural infections. High lymphocyte counts in the initial pleural fluid became high polymorphonuclear cells after several times of thoracentesis. Pneumothorax was found in 2 patients after thoracectesis, who were completely recovered after antibiotic treatment and drainage.
Thoracoscopy was performed directly in one patient receiving oral anticoagulation with warfarin. All patients were well tolerant to thoracoscopy. There were no severe complications including bleeding, inadvertent laceration of lung parenchyma, pulmonary edema, and procedure related death. The volume of drainage through the trocar ranged from 350 ml to 2700 ml. The most common complication was transient chest pain (20/27) from the indwelling chest tube, which was easily controlled with conventional analgesics and disappeared after the removal of the chest tube. Subcutaneous emphysema without any symptoms was found in 1 patient. The condition was not treated because of self-limiting. Two patients experienced fever after thoracoscopy, and they were recovered without treatment the following day.
Drainage of the chest tube was continued for a mean duration of 3.5±1.9 days (range, 1 to 8 days), and no patient required a chest tube for more than 8 days.
DISCUSSION
The value of thoracoscopy for patients with exudative pleural effusion of unknown origin was retrospectively determined in this study. Thoracoscopy made a definite diagnosis in 25 of 27 patients, giving a positive rate of 93%. Before thoracoscopy, only 5 of 23 patients had a definite diagnosis by examinations for pleural effusion, including chest radiography, sputum smears for acid fast bacilli and cytology, and thoracentesis for biochemistry, cytology and microbiology. In the patients receiving routine examinations, 12 were suspected of tuberculous pleurisy, by a positive response to anti-tuberculosis chemotherapy, while in the patients undergoing thoracoscopy, 6 patients with tuberculous pleurisy were confirmed histologically. Thoracoscopy as an established method in the diagnosis of undiagnosed pleural effusions gives a positive rate of 90%.11,12 It is highly sensitive in detecting pleural neoplasia with negative pleural fluid cytology and in the diagnosis of tuberculosis.3 If routine examinations are not helpful, thoracoscopy should be used.
The present study showed several advantages of thoracoscopy. First, thoracoscopy is helpful to determine whether effusion with lung cancer is malignant or paramalignant. As a result, it may be possible to resect a tumor. Cantó et al13 found no thoracoscopic evidence of pleural involvement in 8 of 44 patients, and 6 of the 8 patients had a resection. In our study, one patient with a pulmonary tumor with pleural effusion had no pleural invasion. The patient was proved to have a pulmonary adenocarcinoma with no metastasis.
Second, thoracoscopy is helpful to improve the symptoms of patients with suspected tuberculous pleurisy. The prevalence of tuberculosis is high in China. In 2004 there were 8.9 million new cases of tuberculosis, fewer than half of those reported to the public-health authorities and the World Health Organization.14 Most tuberculosis patients can be cured by anti-tuberculosis chemotherapy. However, some patients with tuberculous pleurisy present with severe adhesions in the pleural cavity and are recovered slowly after the therapy. Wyser and coworkers5 reported the complete drainage of effusion was associated with greater improvement of symptoms. In this study, persistent fever in 2 tuberculous pleurisy patients with pleural adhesions was improved after lysis of the adhesions and drainage of fluid. Thoracoscopy may improve the symptoms of patients or confirm histological diagnosis.
Third, thoracoscopy ensures a definite diagnosis of malignant lymphoma and a more precise classification by a larger, more representative biopsy. In the present study, one patient with a history of pleural effusion for 6 months was accurately diagnosed by direct vision biopsy. Thoracoscopy gave a diagnosis of small B-cell NHL.
Finally, the remaining pleural fluid can be suctioned under continuing visualization, and computed tomography of the thorax may reveal the lung tumor after thoracoscopy. This procedure would benefit patients with larger pleural effusions after a rapid and accurate diagnosis.
In this study, thoracoscopy had a lower rate of complications, and chest pain after the procedure was the most common complication. Loddenkemper15 reported that the most serious, but rare, complication is severe hemorrhage caused by trauma to the blood vessel. Other reported complications are empyema, prolonged air leakage, subcutaneous emphysema, postoperative fever, wound infection, cardiac arrhythmias, hypotension and seeding of chest wall from mesothelioma.9 One case of subcutaneous emphysema and 2 cases of postoperative fever were found in our study. But none of them required active medical management. Complications such as benign cardiac arrhythmias, blood pressure instability, or hypoxemia can virtually be prevented by administration of oxygen. Overall, the side effects of thoracoscopy appear to be few, it is extremely safe. Menzies et al16 reported that 1.9% of patients had major complications and 5.5% had minor complications. Neither morbidity nor mortality was observed during the semi-rigid thoracoscopy by two separate centres, one in North America7 and the other in the United Kingdom17 in 58 patients receiving a total of 60 procedures. In the procedure of thoracoscopy, we found that the technique was similar to chest-tube insertion using a trocar. It is akin to chest tube insertion and can be carried out with a single site of entry under local anaesthesia. 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. Biopsy samples are collected easily through the working channel of a semi-rigid thoracoscope under visual control. With its similarity in design to the flexible bronchoscope, the thoracocope can be used without difficulty.7,18 Thoracoscopy is easy to control within the pleural cavity. The use of fiberoptic bronchoscope in the pleural space has been reported previously.19 The flexibility of the instrument may make maneuvering and steering difficult within the pleural cavity. The semi-rigid thoracoscope offers a solution to some of these problems.
More than half of exudative effusions are due to malignancy. Closed needle biopsy may be successful in 50% of metastatic pleural malignancies;20 however, it is of little value for tumors confined to the diaphragmatic, visceral or mediastinal pleura.21 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% cases) in early stages, it is not possible in these cases to provide a diagnosis by blind needle biopsy.22 Semi-rigid thoracoscopic biopsies can be done for pleural-based abnormalities (for the visualization of abnormal areas and for directed biopsy). The visually guided biopsy of abnormal areas should provide a higher diagnostic rate. This prevents a common problem with blind pleural biopsies, which are often invasive, operator- dependent, technically difficult and non-diagnostic, and thus are rarely used in many hospitals.10
Thoracoscopy is thought to be well-tolerated and less invasive in the management of pleural effusion. However, it is not widely utilized worldwide. A 1995 survey revealed that only 5% of American chest physicians performed the procedure in their practice.8 Another investigation in 2004 showed that 14% of UK respiratory physicians accepted this procedure but only 6% performed 10 procedures.23 Presumably, most of the physicians are not familiar with the use of the rigid thoracoscope let alone they are lack of proper training and the expensiveness of the instrument. The semi-rigid thoracoscope in this study was used as a solution to some of these problems. The design of the instrument is similar to that of the commonly used bronchoscope. It is less expensive because of its compatibility with the video processors and light sources available in most bronchoscopic units. The working channel is similar to the conventional bronchoscope, allowing the use of standard flexible biopsy forceps and minimizing the use of additional equipments.7
In spite of the advantages, the costs of semi-rigid thorocoscopy related examination are a matter of concern. Repeated large volume thoracentesis may increase costs and pain. In this study, no difference in costs was observed between thoracoscopy and routine examination (P=0.114). In patients receiving routine examination, they had more thoracentesis, B-ultrasound examinations, B-ultrasound guided pleural aspiration, and costs than those receiving thoracoscopy. Recurrent thoracentesis induced pleural infections in 2 cases and pneumothorax in 2.
Although it is efficient and safe in management of undiagnosed pleural effusions, there is no evidence available for determining for whom with pleural effusion thoracoscopy is indicated. Ferrer et al24 suggested that the application of clinical and radiologic criteria and predictive criteria of malignancy might improve the indications of thoracoscopy for patients with undiagnosed pleural effusion. These include a symptomatic period > 1 month, absence of fever, blood-tinged pleural fluid, and chest CT scan. The 2000 American Thoracic Society statement20 on management of malignant pleural effusions states that “in cases of undiagnosed exudative effusions with a high clinical suspicion for malignancy, some clinicians may proceed directly to thoracoscopy if the facilities for medical thoracoscopy are available.” In this study, semi-rigid thoracoscopy was performed after routine examinations, including at least one thoracentesis. There is no consensus on for whom with pleural effusion thoracoscopy is indicated, but the procedure done as soon as possible would benefit the patients after a rapid and accurate diagnosis.
In summary，semi-rigid thoracoscopy is simple, safe, and cost-effective with a high positive rate. Its convenience and compatibility with existing bronchoscopy make the technique a more widely performed procedure. Thus, it is worth proceeding actively for proper patients if the facilities for thoracoscopy are available. It is valuable in the investigation and management of undiagnosed pleural effusions.
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