Evaluation of ejectors using the venturi effect for a continuous positive airway pressure system without compressed air.

The purpose of this study is to perform a test in the application of the existing ejectors with the continuous positive airway pressure (CPAP) system without compressed air. Four types of ejector (jet mixer, the former and new puritan nebulizer and the deluxe nebulizer) for blending oxygen and room air by the Venturi effect were tested. A decrease of mixed gas flow and an increase of oxygen concentration were observed according to the increase of positive pressure in all systems. The former puritan nebulizer and deluxe nebulizer were found to be unavailable for the CPAP system for high oxygen concentration and low mixed gas flow for the increase of positive pressure. In the system, however, with the new puritan nebulizer and jet mixer, a sufficient mixed gas flow and an appropriate oxygen concentration could be supplied at an adequate positive pressure. The CPAP system using only oxygen was judged as possibly giving availability.