An improved Boussignac device for the delivery of non-invasive CPAP: The SUPER-Boussignac

Purpose: The purpose of this study is to describe and test a modified Boussignac system for non-invasive continuous positive airway pressure, aimed at reducing the decrease in inspiratory oxygen fraction (FiO2) with higher inspiratory peak flow rates. Methods: We modified a Boussignac circuit by inserting a T-piece between the Boussignac valve and the face mask. The T-piece was connected to a reservoir balloon receiving oxygen by an independent source. The system was tested in a bench study, consisting of five steps, with increasing inspiratory peak flow rates (Vinsp). Three levels of PEEP were tested: 7, 10 and 13 cmH2O. The following devices were tested: Boussignac, Boussignac with reservoir but without supplementary oxygen, Boussignac with reservoir and 10 (SUPER-Boussignac10) and 30 l/min (SUPER-Boussignac30) of supplementary oxygen. In each step we measured FiO2, tidal volumes, and airway pressure. Results: FiO 2 increased with PEEP and decreased at increasing Vinsp with all the systems. However, FiO2 increased with SUPER-Boussignac10 (7-10%) and with SUPER-Boussignac30 (10-30%). Moreover, in the latter case, for Vinsp values up to 60 l/min, FiO2 became independent of Vinsp. The SUPER-Boussignac allowed also smaller drop in airway pressure during inspiration and higher tidal volumes. Conclusions: The SUPER-Boussignac represents a simple way to significantly improve the performance of the Boussignac device.