Evaluation of a flexible bronchoscope prototype designed for bronchoscopy during mechanical ventilation: a proof-of-concept study.

Bronchoscopy during mechanical ventilation of patients' lungs significantly affects ventilation because of partial obstruction of the tracheal tube, and may thus be omitted in the most severely ill patients. It has not previously been possible to reduce the external diameter of the bronchoscope without reducing the diameter of the suction channel, thus reducing the suctioning capacity of the device. We believed that a better-designed bronchoscope could improve the safety of bronchoscopy in patients whose lungs were ventilated. We designed a flexible bronchoscope prototype with a drumstick-shaped head consisting of a long, thin proximal portion; a short and large distal portion for camera docking; and a large suction channel throughout the length of the device. The aims of our study were to test the impact of our prototype on mechanical ventilation when inserted into the tracheal tube, and to assess suctioning capacity. We first tested the efficiency of the suction channel, and demonstrated that the suction flow of the prototype was similar to that of conventional adult bronchoscopes. We next evaluated the consequences of bronchoscopy when using the prototype on minute ventilation and intrathoracic pressures during mechanical ventilation: firstly, in vitro using a breathing simulator; and secondly, in vivo using a porcine model of pulmonary ventilation. The insertion of adult bronchoscopes into the tracheal tube immediately impaired the protective ventilation strategy employed, whereas the prototype preserved it. For the first time, we have developed an innovative flexible bronchoscope designed for bronchoscopy during invasive mechanical ventilation, that both preserved the protective ventilation strategy, and enabled efficient suction flow.

The effect of fibreoptic bronchoscopy in acute respiratory distress syndrome: experimental evidence from a lung model.

Flexible bronchoscopy is essential for appropriate care during mechanical ventilation, but can significantly affect mechanical ventilation of the lungs, particularly for patients with acute respiratory distress syndrome. We aimed to describe the consequences of bronchoscopy during lung-protective ventilation in a bench study, and thereby to determine the optimal diameter of the bronchoscope for avoiding disruption of the protective-ventilation strategy during the procedure. Immediately following the insertion of the bronchoscope into the tracheal tube, either minute ventilation decreased significantly, or positive end-expiratory pressure increased substantially, according to the setting of the inspiratory pressure limit. The increase in end-expiratory pressure led to an equivalent increase in the plateau pressure, and lung-protective ventilation was significantly altered during the procedure. We showed that a bronchoscope with an external diameter of 4 mm (or less) would allow safer bronchoscopic interventions in patients with severe acute respiratory distress syndrome.