Investigation of the flexibility of bronchoscopes

OBJECTIVE: For transbronchial biopsy of peripheral pulmonary lesions manouevering the biopsy instrument into acutely angulated subsegmental ostia is frequently problematic. The aim of the present study was to compare the stiffness of various biopsy instruments with regard to their use in the clinical setting. METHODS: The maximal anterograde and retrograde bending angles, were measured for various bronchoscopes and biopsy instruments. Measurement was made with the distal tip of the biopsy instrument either flush with the distal end of the bronchoscope, or extending 1.5 cm beyond it. The following scopes and biopsy instruments were investigated: 1. the 6.2 mm outside diameter (OD) bronchoscope, with the 2.4 mm OD forceps, 0.7 mm needle, 2.3 mm catheter, and the 1.9 mm cryoprobe. 2. the 5.1 mm OD bronchoscope, with the 1.8 mm forceps, 0.7 mm needle, and the 1.8 mm catheter. 3. the 3.7 mm bronchoscope, with the 1.0 mm forceps and the 0.8 mm forceps. RESULTS: Maximum angulation was greater by 35.4° with the needle extended, vis-à-vis the needle "flush". Both needle and catheter were associated with a greater angulation of up to 20.5° in comparison with the forceps. With an instrument in the working channel the largest anterograde angles were measured for the 5.1 mm bronchoscope, and the largest retrograde angles for the 6.2 mm bronchoscope. CONCLUSION: When selecting the optimal instrument for transbronchial biopsy specimen collection, account must be taken of the fact that the degree of angulation will depend on the type and diameter of the instrument employed.