Modeling the Pulmonary Mechanics of Jet Ventilation During Rigid Bronchoscopy

Rigid bronchoscopy is a procedure which allows for surgical interventions in the trachea and central airways for which patients frequently require general anesthesia and ventilatory support. Low-frequency jet ventilation (LFJV) is a technique to provide ventilatory support for rigid bronchoscopy in which the anesthesiologist manually delivers jets of air to the patient with a hand-controlled valve. The airway pressures and tidal volumes during LFJV are poorly characterized. We conducted a benchtop experiment using a mechanical model lung and a custom-built sensor array to measure airway pressure and tidal volume and determine the effect of airway resistance, lung compliance, inspiratory time, and expiratory time during LFJV. Median airway pressure was 10.99 cm H2O, range 7.69 – 12.02 cm H2O. Resistance and compliance each had a statistically significant effect on airway pressure, although the magnitude of this effect was small. Median tidal volume was 177 mL, range 43 – 546 mL. Inspiratory time, resistance and compliance all had statistically significant effects on tidal volume, however only compliance had a clinically relevant effect on tidal volume with higher levels of compliance leading to larger tidal volumes. Our data suggests LFJV for rigid bronchoscopy is a low-pressure ventilation strategy where tidal volume is primarily determined by lung compliance.