Jet ventilation in upper airway obstruction: description and model lung testing of a new jetting device.

UNLABELLED

Patients with critical upper airway stenosis require a tracheotomy for corrective surgery. We describe a new transtracheal device that permits safe ventilation of these patients without tracheotomy. It is based on a coaxial bicannular design that allows "push-pull" ventilation by jetting gas through the inner cannula and applying suction through the outer cannula. It further allows monitoring of airway pressure, tidal volume, and end-tidal CO2. The device was placed in the "trachea" of an artificial lung, and the preparation was made airtight by sealing the proximal end of the trachea. Tidal volumes and their associated pressures were measured simultaneously at different parts of the airway at several lung compliances and airway resistance settings while varying the jet and suction pressures. A large range of tidal volumes was achieved at safe airway pressures using clinically relevant airway resistance and lung compliance settings. Airway pressures measured through the device correlated well with pressures measured directly in the airways at the same time. Tidal volumes, measured through a Wright respirometer in the suction line, exceeded actual values at high suction settings and decreased below actual values at low suction settings. This new form of jet ventilation allowed efficient ventilation of the artificial lung with a totally occluded upper airway.

IMPLICATIONS

Tracheotomy is required for surgery to relieve stridor because gas forced into the trachea at high pressures through a percutaneously placed needle (jetting) cannot be exhaled quickly enough for respiration. We describe a device that allows jetting in the stridorous patient by actively assisting expiration, thereby eliminating the tracheotomy requirement.