Evaluation of the jet injector in paediatric fibreoptic bronchoscopes

The use of the Sanders venturi system during bronchoscopy in adults has been studied extensively. Its use in paediatric bronchoscopy has been limited because small changes in the characteristics of the system may produce large changes in the patient. With jet ventilation, peak inflation pressures and flow rates are influenced by the driving pressure, diameter and shape of the bronchoscope, the diameter of the injector and its length and angle from the axial line of the bronchoscope. Storz 3 mm, 4 mm and 5 mm rigid fibreoptic bronchoscopes were evaluated in a test lung with an injector of 1.5 mm internal diameter fixed in the side-arm at 20 degrees to the axial line. Pilling 3 mm, 4 mm and 5 mm rigid fibreoptic bronchoscopes were also examined using the standard injector with a 0.89 mm orifice in the axial line. The Storz bronchoscopes produced consistently higher peak inflation pressures and flow rates at all driving pressures in spite of the relatively large angle of the injector from the axial line. Caution is advised in the use of the Storz injector system as excessively high inflation pressures may be reached.