Jet ventilation in support of fiberoptic bronchoscopy

Mechanical ventilatory support of bronchoscopic procedures by conventional volume-cycled ventilation (VCV) is technically difficult and can result in unreliable gas delivery or excessive alveolar pressure. An alternate support mode is jet ventilation through an open, uncuffed endotracheal tube. To quantitate gas delivery and airway pressures (Paw) during bronchoscopy using this technique, we used a mechanical-lung model and 15 human subjects. Jet ventilation pulsed gases at 60 to 100 cycle/min through a catheter in an uncuffed, jet endotracheal tube with a 5.9-mm (OD) bronchoscope in place. Inspiratory time was constant at 33% of cycle time, and jet-drive pressures ranged from 5 to 30 psi. In the mechanical-lung model, the jet technique provided up to 30 L/min of ventilation with mean airway pressures (Paw) always less than 10 cm H2O. In contrast, VCV with an inflated cuff, while providing similar levels of ventilation, resulted in substantial air trapping and over twice the Paw. VCV with a deflated cuff provided much lower levels of ventilation, although Paw levels were also low. These delivered minute ventilations, and Paw levels were similar in six normal volunteers jet ventilated through a 9-mm jet endotracheal tube with a bronchoscope in place. Finally, in nine patients requiring mechanical ventilatory support during bronchoscopic procedures, this jet technique provided alveolar ventilation (i.e., PaCO2) and Paw levels comparable to those obtained on baseline VCV before bronchoscopy.