Pleural disease may sometimes present a diagnostic challenge to the respiratory physician. The diagnostic yield from thoracocentesis and/or closed pleural biopsy is poor, leaving between 25% and 40% of pleural abnormalities undiagnosed.1,2 Medical thoracoscopy (pleuroscopy) achieves a positive diagnosis in >90% of pleural effusions.3,4 It allows direct inspection of the pleura, targeted pleural biopsy, drainage of fluid, and chemical pleurodesis in 1 sitting. It is remarkably well tolerated, and unlike video-assisted thoracoscopic surgery (VATS), a general anesthetic is not required.
Worldwide, the most widely used instrument is the rigid thoracoscope. However, this may be an unfamiliar tool to most respiratory physicians.5 A semirigid thoracoscope, similar in design to the commonly used fiberoptic bronchoscope, is available: however, until recently, its use in the United Kingdom has been very limited because of its sterilization requirements with ethylene oxide, which is not allowed in this country.6 However, an autoclavable version has been produced and the instrument is gaining in popularity.7
The larger biopsy size afforded by the rigid thoracoscope has been suggested as a reason for its superiority. However, there is no published evidence to prove this. We present the first direct comparison of the histologic diagnostic yields of the rigid and the semirigid thoracoscopes.
PATIENTS AND METHODS
Two centers in the north west of England were involved in this study. Consecutive patients with clinical and radiologic evidence of a unilateral pleural effusion were enrolled. All patients had “suspicious,” “normal,” negative, or unsuccessful blind pleural fluid cytology. Apart from 3 in the rigid group, all patients had a contrast-enhanced computed tomography scan of the thorax before the procedure. One operator (S.A.) examined 29 patients using the Wolf rigid thoracoscope (Richard Wolf GmbH, Knittlingen, Germany) at North Manchester General Hospital between November 2003 and September 2005. The other operator (M.M.) examined 42 patients using the prototype semirigid XLTF-160Y1 thoracoscope (Olympus, Tokyo, Japan; supplied by Olympus KeyMed UK, Southend-on-Sea, UK) at the Royal Preston Hospital between June 2004 and November 2005.
Written informed consent was obtained in all cases. Patients were placed in the lateral decubitus position with the affected lung uppermost. Oxygen saturations and pulse rate were monitored throughout. Oxygen was provided by mask or nasal cannulae while conscious sedation was administered using a combination of intravenous midazolam and alfentanil. Local anesthesia (lidocaine 1%) was administered to the skin and parietal pleura, and blind fluid aspiration was attempted. If successful, an incision was made in the midaxillary line and a 10-mm trocar was placed through the skin into the pleural space. Confirmation of parietal pleural puncture was made by air leak or paradoxical respiration. The Wolf rigid thoracoscope or Olympus semirigid thoracoscope was inserted through the trocar, and the pleural fluid was aspirated to dryness. The pleural surfaces were then inspected and photographed as necessary. One rigid thoracoscopy was performed using the dual port technique. A minimum of 6 and a maximum of 10 biopsy samples were taken: the operator determined the number of specimens for each procedure on the basis of the macroscopic adequacy of the samples. M.M. used Olympus FB-240K oval fenestrated biopsy forceps, whereas S.A. used Wolf 5-mm biopsy forceps. Where clinically appropriate, talc poudrage was performed using 5 g sterile talc aerosol (Novatech SA, La Ciotat, France). Finally, a large-bore (24F) thoracic drain (Portex, Smiths Medical International, Watford, UK) was inserted through the trocar and secured. A chest radiograph was used to confirm drain position and ensure lung reinflation. A full operative record was maintained. No drain remained inserted for longer than 48 hours. After drain removal, the skin defect was sutured and the wound was dressed.
The primary outcome measure was the demonstration of statistical equivalence between the diagnostic histologic yields of the 2 instruments.
Seventy-two procedures were attempted at both centers between November 2003 and November 2005. All patients examined had a unilateral exudative pleural effusion without definitive diagnosis after pleural fluid cytology. S.A. attempted 29 procedures with the rigid thoracoscope and M.M. attempted 43 with the semirigid instrument. In the rigid group, there were 2 failed procedures; in the semirigid group, 1 procedure was abandoned (details of these procedures are in the last paragraph in this section). In another patient in the semirigid group, histologically adequate material could not be obtained and a second procedure had to be undertaken, which yielded satisfactory biopsy material.
Unexpectedly, there were 2 findings of empyema in the semirigid group. These were not suspected clinically before the procedure, and previous pleural aspiration had not yielded frankly purulent fluid or a positive microbiological culture. The diagnosis was established only when the purulent fluid was aspirated thoracoscopically from the pleural space. Culture from these samples was also ultimately negative, but the patients responded well to antimicrobial therapy and intercostal tube drainage. As pleural biopsy samples were not taken from these patients, they were excluded from the analysis.
In the end, therefore, 66 procedures were included in the analysis: 27 from the rigid group and 39 from the semirigid group.
The median patient age was 68 years, with an age range between 30 and 89 years. Forty-one of the patients were male and 25 were female.
The procedure was well tolerated by all patient Table 1.
The 17 patients with final histologic diagnoses of inflammation/reactive change, plaque, fibrosis, and normal pleura had a history suggestive of infection, asbestos exposure, or rheumatoid arthritis. After the biopsy results, clinical diagnoses of postpneumonic effusion, rheumatoid effusion, and benign asbestos effusion were made. These patients had no clinical or radiographic features to suggest that further investigation was warranted. Their subsequent clinical course has given no cause to believe otherwise.
Thoracoscopic pleural biopsy achieved a diagnosis in 26 of 27 patients in the rigid thoracoscopy group (96.3% positive yield). In the semirigid thoracoscopy group, a diagnosis was reached in 36 of 39 patients, giving a positive yield of 92.3%. There was no statistically significant difference between these proportions (95% confidence intervals, −0.11 to 0.17). Four patients did not receive a satisfactory diagnosis from thoracoscopy. One such patient in the rigid thoracoscopy group was eventually diagnosed with mesothelioma after VATS in the theater. In 3 such patients in the semirigid thoracoscopy group, diagnosis was established using other techniques: (i) 1 patient was shown to have metastatic adenocystic salivary gland adenocarcinoma after an ultrasound-guided salivary gland biopsy; (ii) the second patient was diagnosed with metastatic colonic adenocarcinoma after lower gastrointestinal endoscopy; and (iii) the third patient had a history of gastric non-Hodgkin lymphoma. After the negative thoracoscopy, a clinical decision to treat for relapsed lymphoma was made; this cleared the pleural disease completely. In the rigid thoracoscopy group, 1 procedure was poorly tolerated and halted for patient comfort; in another procedure, diagnostic sampling was rendered impossible by dense adhesions within the pleural cavity. In addition, in this group, there was 1 incidence of pneumonitis and 1 episode of surgical emphysema because of the thoracic drain. Three patients had low-grade pyrexia and 1 had a myocardial infarction 72 hours after the procedure.
In the semirigid group, 1 procedure was abandoned as the pleural fluid could not be aspirated despite multiple attempts.
This study shows that when used in the evaluation of a unilateral pleural effusion (where needle aspiration has been nondiagnostic), there is no difference in the diagnostic yields of the rigid and the semirigid thoracoscopes.
The initial investigation of choice for a unilateral pleural effusion remains needle thoracocentesis: it is simple and minimally invasive. However, pleural fluid aspiration on its own has a poor diagnostic yield: as low as 20% in malignant mesothelioma.8 When thoracocentesis fails to reveal a cause in a unilateral exudative effusion, some form of pleural tissue sampling is required. In the United Kingdom, some physicians will still perform a closed pleural biopsy using a Cope or Abrams needle. Unfortunately, the combination of thoracocentesis and closed biopsy will still leave 25% to 40% of patients without a clear diagnosis.1,2
For this reason, the British Thoracic Society recommends thoracoscopy as the next line of investigation after a negative or inconclusive pleural fluid aspirate in the setting of an exudative pleural effusion.9 Image-guided biopsy (computed tomography or ultrasound) is described as an alternative, and while it has good sensitivity (88%), thoracoscopy has the considerable advantage of allowing pleural fluid drainage and chemical pleurodesis in the same sitting.10 In addition, image-guided biopsy is feasible only in the presence of a radiologically demonstrable focal abnormality of the pleura.
Despite its obvious advantages, the practice of thoracoscopy in most countries, including the United Kingdom, remains limited. A 2004 survey revealed that only 14% of UK respiratory physicians had any exposure to it at all, and only 6% had performed >10 procedures.11 Respiratory physicians will often refer patients for VATS, which requires operating room facilities and the use of a general anesthetic. However, many patients with suspected malignant pleural disease are frail and elderly and have multiple comorbidities, which makes general anesthesia hazardous. In addition, access to thoracic surgeons who perform VATS is limited in the United Kingdom, which often means that patients have to wait unacceptably long for the operation.
One reason for the poor uptake of thoracoscopy by respiratory physicians may be unfamiliarity with the conventional rigid instrument, as the majority of pulmonology training programs in the United Kingdom and the United States offer no formal training in its use.5,12 The semirigid thoracoscope is similar in design and use to the flexible bronchovideoscope, and although formal training will always be required, it is likely that operators will be able to adapt to its use more easily. The development of the autoclavable version will hopefully expand its use in the United Kingdom and other countries.7
An oft-quoted criticism of the semirigid thoracoscope is the smaller biopsy size of 2 mm. It has been suggested that this will compromise the diagnostic yield.13 However, a 2007 series of 56 patients investigated with the semirigid instrument reported a positive yield of 90.7%.7
Significant limitations of the current study include the lack of randomization and the fact that there was a different operator at a different institution for each instrument. Both operators had just started performing medical thoracoscopy and were in the early part of the learning curve.
Nevertheless, our retrospective comparison of 2 cohorts each using a different kind of thoracoscope is the first such series to be published. We have demonstrated that there is no significant difference in diagnostic pickup rate between the 2 instruments, and that a smaller biopsy size does not necessarily imply an inferior result. Although the rigid instrument will continue to retain its valuable place in the diagnosis and management of pleural disease, the newer semirigid thoracoscope also offers excellent results. We believe that its similarity to the flexible bronchovideoscope and its compatibility with existing bronchoscopy light sources and video processors will expand the practice of thoracoscopy by respiratory physicians in the United Kingdom and other countries.
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