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 (JOURNAL/incm/04.02/00004464-200906000-00020/OV0312/v/2017-10-18T124439Z/r/image-pnginsp). 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
FiO2 increased with PEEP and decreased at increasing JOURNAL/incm/04.02/00004464-200906000-00020/OV0312/v/2017-10-18T124439Z/r/image-pnginsp with all the systems. However, FiO2 increased with SUPER-Boussignac10 (7–10%) and with SUPER-Boussignac30 (10–30%). Moreover, in the latter case, for JOURNAL/incm/04.02/00004464-200906000-00020/OV0312/v/2017-10-18T124439Z/r/image-pnginsp values up to 60 l/min, FiO2 became independent of JOURNAL/incm/04.02/00004464-200906000-00020/OV0312/v/2017-10-18T124439Z/r/image-pnginsp. 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.