Additional Techniques to Aid Flexi-rigid Pleuroscopy
Procuring adequate samples from thickened pleura remains the most important limitation of flexi-rigid pleuroscopy. Patients with mesothelioma or benign fibrothorax (e.g. benign asbestos pleural disease, TB pleural fibrosis, etc.) are often challenges for the users of flexi-rigid pleuroscopes. Cytology has lower yield with mesothelioma and the current guidelines favor histological specimens over pleural fluid cytology in diagnosing mesothelioma. Therefore, obtaining representative biopsy samples is crucial in these patients.
To overcome the limitation of small biopsies by flexi-rigid pleuroscope, different strategies have been explored. Taking repeated 'bites' from the same site with the flexible forceps to obtain tissue of sufficient depth and peeling away the pleura and removing it together with the pleuroscope through the trocar are tedious and time-consuming. Alternatively, swapping flexi-rigid pleuroscopy over to rigid thoracoscopy during the procedure is an option. However, not all units are equipped with both types of instruments.
A simpler alternative is to insert a second entry port for the rigid optical biopsy forceps. The flexi-rigid scope then provides the direct vision to guide biopsies with the rigid forceps. This method combines the better optics of the flexi-rigid pleuroscope with the larger biopsies from using rigid forceps.
Several accessories have been designed to improve the biopsy of thickened pleura to be used via the working channel of the flexi-rigid pleuroscope, without the need of creating a second entry port. The insulated-tip knife consists of a conventional diathermic knife with a ceramic ball at the tip to limit the depth of the cut. Sasada et al. showed, in a study of 20 patients, that the insulated-tip knife allowed full-thickness parietal pleural biopsy with a higher diagnostic yield (85%) when compared with the standard flexible forceps (60%).
Biopsy via a cryoprobe is another tool being tested. Since its first use in 1968, cryosurgical technique has mainly been employed in the management of obstructive endobronchial tumors. The equipment consists of a console, cryogen and cryoprobe. The Joule–Thomson effect states that a compressed gas released at a high flow rapidly expands and creates a very low temperature. The cryoprobe is compatible with the working channel of the flexi-rigid pleuroscope and is pressed against the targeted pleural lesion (Fig. 7). The tissue is frozen under direct vision, detached with a tug and removed together with the scope. Anecdotally, cryobiopsy can help to obtain larger size pleural samples even in thickened pleura.
These tools, and others in development, can potentially allow adequate sampling of thickened pleura, thus offsetting the key limitation of flexi-rigid pleuroscopy.
Curr Opin Pulm Med. 2014;20(4):358-365. © 2014 Lippincott Williams & Wilkins