[Effect of various tracheal diameter forms on airway pressure in experimental intratracheal injector ventilation]

Experimental catheter jet ventilation was performed on tracheal models of four sizes and six different shapes. Three coaxial jet positions were tested: centrally, adjacent to the wall and in a corner of the model. Driving gas pressure and size of the jet were kept constant. Airway pressure declines as the models increase in size. In the corner position, airway pressure is always less than in the centre position. In models with equal cross-section areas, airway pressure differs in all other shapes from that of the cylindrical shape. With this equipment, airway pressures between 9 and 14 cm H2O were achieved in cylindrically-shaped tracheas of a diameter of 15 resp. 20 mm. With the same transverse diameters, but with clinically relevant different tracheal shapes and jet positions, however, the values may vary from 18 cm H2O to less than 5 cm H2O.