Rigid vs. Flexi-rigid Pleuroscopy: The Instruments
A rigid thoracoscopy set includes a telescope, light source, trocar and forceps. The conventional stainless steel rigid telescope is 27–31 cm in length with a diameter of 7–12 mm, the larger ones (10–12 mm) often being favored by surgeons. Rigid telescopes have different angles of vision permitting straight-on (0°) or oblique (30° or 50°) viewing. Trocars are made from single-use disposable plastic or stainless steel with a variable diameter of 5–13 mm.[4,5]
The autoclavable flexi-rigid (semi-rigid) pleuroscope (Olympus LTF 160 or 240) has a 22 cm proximal rigid shaft and 5 cm flexible distal tip with an outer diameter of 7 mm. The flexible tip allows two-way angulations (160° up and 130° down). The handle of the flexi-rigid pleuroscope is similar to that of a flexible bronchoscope complete with a 2.8 mm working channel, lever and suction port (Fig. 1). The scope utilizes a custom-made plastic trocar of 8 mm diameter (Fig. 2).[6,7]
The key difference between the two instruments is the flexibility to navigate various parts of the pleural cavity. The rigid thoracoscope has to travel in a straight line and has limited maneuverability when examining the posterior and mediastinal aspects of the thoracic cavity, particularly if the lung remains partially or fully inflated. The operator inevitably has to angle the scope by levering it against the underlying rib. The pressure and angling of the rigid instrument over the periosteum are believed to cause pain. The flexi-rigid pleuroscope, on the other hand, provides more flexibility[6,8] and allows the operator to negotiate around a nondeflated lung or dense adhesions. In very loculated effusions, the ability to retroflex the pleuroscope to biopsy the parietal pleura adjacent to the insertion site is advantageous (Fig. 3). This is not feasible with rigid thoracoscopy.
For visualization and illumination, the flexi-rigid pleuroscope can be connected to the existing endoscopic processors (Olympus CV-160 and CLV-U40) and light sources (CV-240, EVIS-100 or 140, and EVIS EXERA-145 or 160), whereas the rigid thoracoscope requires a separate cold light source (xenon) with a camera attached to the eye-piece of the telescope.[6,7] The image quality is significantly better with the flexi-rigid pleuroscope.
The 'trade-off' and key disadvantage of the flexi-rigid scope is the small working channel which can limit adequate biopsies. The cusps diameter of the flexible biopsy forceps (FB-55CR-1) used with the flexi-rigid scope is 2.4 mm, considerably smaller than that of the optical rigid biopsy forceps (5 mm) used with rigid thoracoscopes (Fig. 4). The flexible forceps also lack the mechanical strength in obtaining specimens from tough fibrous pleura. Therefore, the sturdier rigid biopsy forceps, usually used during rigid thoracoscopy, often facilitate bigger and deeper biopsies and are more efficient in breaking down adhesions.
Rigid optical biopsy forceps and flexible biopsy forceps – showing the smaller size of the latter.
This difference is probably of less clinical importance if the patient has nodular pleural abnormalities (often seen with metastatic carcinomas; Fig. 5), which are easy to capture even with flexible biopsy forceps, but is a significant limitation in patients with densely thickened pleura (Fig. 6). The latter can be seen with patients with mesothelioma (especially the sarcomatoid subtype) and fibrothorax from any chronic pleuritis. This is noteworthy as mesothelioma is consistently the most common cause of false-negative biopsies in patients with pleural malignancies undergoing medical thoracoscopy in published series, even when rigid scopes were used.[10–12]
Malignant pleural nodule: such lesions are easy to biopsy regardless of whether flexi-rigid or rigid instruments are used.
Curr Opin Pulm Med. 2014;20(4):358-365. © 2014 Lippincott Williams & Wilkins