Effectiveness of tip rotation in fibreoptic bronchoscopy under different experimental conditions: an in vitro crossover study

The difference in rotation angle of the distal endotracheal tube through nasal approach

BACKGROUND

Nasal intubation using a fiberoptic scope is a useful technique. In clinical practice, we have experienced difficulty in advancing the endotracheal tube (ETT) over the fiberoptic scope because of resistance to the passage of the ETT against rotation in the nasal cavity, when it gets hung up on structures of the laryngeal inlet. Several maneuvers have been proposed to overcome this difficulty. The gap between the tip of the ETT and the fiberoptic scope can be reduced using a thicker fiberoptic scope and a thinner ETT. Moreover, simultaneous rotation of the fiberoptic scope and ETT could lead to successful intubation by reducing impingement on the ETT. However, the discrepancy between these rotation angles is unclear. This observational prospective study aimed to investigate the discrepancy in the rotation angle between the ETT and fiberoptic scope during nasal intubation.

METHODS

The patients (aged 20-80 years) who underwent nasal intubation for oral and maxillofacial surgery participated in three sizes of preformed nasal ETT and were intubated using a fiberoptic scope. They were divided into three groups; the ETT internal diameter (ID) 6.5 mm (6.5 group), ID 7.0 mm (7.0 group), and ID 7.5 mm (7.5 group). The ETT was then inserted through the nasal cavity into the pharynx. After the fiberoptic scope was advanced through the ETT above the glottis, simultaneous rotation by both the proximal end of the fiberoptic scope and ETT was performed in 90° and 180° in both right (clockwise) and left (counterclockwise) directions, and the rotation angle at the distal end of the ETT was monitored using a video laryngoscope (Pentax-AWS).

RESULTS

A total of 39 patients were included in the study. When both the proximal end of the fiberscope and ETT were simultaneously rotated by 90°, in the 6.5 group (n = 13), the distal end of the ETT rotated by 47.8 ± 1.5°. In the 7.0 °group (n = 13), the distal end of the ETT rotated by 45.5 ± 1.0°. In the 7.5 group (n = 13), the distal end of the ETT rotated by 39.9 ± 1.0°. When the proximal end of the fiberscope and ETT were rotated by 180°, in the 6.5 group, the distal end of the ETT rotated by 166.2 ± 2.5°. In the 7.0 group, the distal end of the ETT rotated by 145.7 ± 2.2°. In the 7.5 group, the distal end of the ETT rotated by 115.1 ± 2.0°. All rotation angles in the distal end of the ETT were significantly lower than those in both the proximal end of the fiberscope and ETT (p < 0.05). Rotating right by 180° was significantly different among the three groups (p < 0.05), although rotating right by 90° was not significantly different. Similar results were obtained for the left rotation.

CONCLUSION

Simultaneous rotation by the proximal end of the ETT and fiberscope above the glottis for the nasal approach induced significant differences in the distal end of the ETT. The larger tube lagged by the resistance of the nasal passages during rotation. Therefore, the ETT does not rotate as much as the rotation angle.

TRIAL REGISTRATION

This prospective observational study was conducted after receiving approval from the Ethics Review Board of Kyushu University Hospital (Approval No. 30-447).

Predicting reachability to peripheral lesions in transbronchial biopsies using CT-derived geometrical attributes of the bronchial route

PURPOSE

The bronchoscopist's ability to locate the lesion with the bronchoscope is critical for a transbronchial biopsy. However, much less study has been done on the transbronchial biopsy route. This study aims to determine whether the geometrical attributes of the bronchial route can predict the difficulty of reaching tumors in bronchoscopic intervention.

METHODS

This study included patients who underwent bronchoscopic diagnosis of lung tumors using electromagnetic navigation. The biopsy instrument was considered "reached" and recorded as such if the tip of the tracked bronchoscope or extended working channel was in the tumors. Four geometrical indices were defined: Local curvature (LC), plane rotation (PR), radius, and global relative angle. A Mann-Whitney U test and logistic regression analysis were performed to analyze the difference in geometrical indices between the reachable and unreachable groups. Receiver operating characteristic analysis (ROC) was performed to evaluate the geometrical indices to predict reachability.

RESULTS

Of the 41 patients enrolled in the study, 16 patients were assigned to the unreachable group and 25 patients to the reachable group. LC, PR, and radius have significantly higher values in unreachable cases than in reachable cases ([Formula: see text], [Formula: see text], [Formula: see text]). The logistic regression analysis showed that LC and PR were significantly associated with reachability ([Formula: see text], [Formula: see text]). The areas under the curve with ROC analysis of the LC and PR index were 0.903 and 0.618. The LC's cut-off value was 578.25.

CONCLUSION

We investigated whether the geometrical attributes of the bronchial route to the lesion can predict the difficulty of reaching the lesions in the bronchoscopic biopsy. LC, PR, and radius have significantly higher values in unreachable cases than in reachable cases. LC and PR index can be potentially used to predict the navigational success of the bronchoscope.