Clinical experience of the newly devised direct bronchoscope with a long built in channel for high frequency jet ventilation(HFJV).

Since 1982, we had used the Jackson-Ono's direct bronchoscope with Tanaka's adapter for HFJV. This device was attached to the proximal end of the bronchoscope, and had a short channel for HFJV. However, this method resulted in high PaCO2 (mean 63.9±20.5mmHg) during long surgical procedure. Therefore, controlled respiration was intermittently required to increase the ventilatory flow per minute.Recently, a bronchoscope with a long built-in channel has been devised at our department, in which spouting orifice of the oxygen is located inside the scope approxymately 6cm proximal from the tip. Since 1986, this device has been applied to 9 patients with bronchial foreign bodies and relatively lower PaCO2 (mean 29.3±11.3mmHg) has been observed during the surgical procedure.Several basic experiments were performed to clarify the mechanism of better clinical results in blood gas analysis using a model of lung and bronchus complex. Following results were obtained: (1) the pressure at the distal end of the newly devised bronchoscope was significantly higher; (2) the ventilatory flow rate per minute was significantly higher than that of conventional bronchoscope with Tanaka's adapter; (3) there was no significant difference in airway pressure between these two instruments. From these results we concluded that the reason why low PaCO2 could be maintained with newly developed bronchoscope during long manipulation was due to high ventilatory flow rate in spite of the similar airway pressure inside the bronchus.