Noninvasive CPAP with face mask: Comparison among new air-entrainment masks and the boussignac valve

摘要

BACKGROUND: The performances of 2 noninvasive CPAP systems (high flow and low flow air-entrainment masks) were compared to the Boussignac valve in 3 different scenarios. METHODS: Scenario 1: pneumatic lung simulator with a tachypnea pattern (tidal volume 800 mL at 40 breaths/ min). Scenario 2: Ten healthy subjects studied during tidal breaths and tachypnea. Scenario 3: Twenty ICU subjects enrolled for a noninvasive CPAP session. Differences between set and effective CPAP level and FIO2, as well as the lowest airway pressure and the pressure swing around the imposed CPAP level, were analyzed. The lowest airway pressure and swing were correlated to the pressure-time product (area of the airway pressure curve below the CPAP level) measured with the simulator. PaO2 was a subject's further performance index. RESULTS: Lung simulator: Boussignac FIO2 was 0.54, even if supplied with pure oxygen. The air-entrainment masks had higher swing than the Boussignac (P = .007). Pressure-time product correlated better with pressure swing (Spearman correlation coefficient [ρ] = 0.97) than with lowest airway pressure (ρ = 0.92). In healthy subjects, the high-flow air-entrainment mask showed lower difference between set and effective FIO2 (P.001), and lowest airway pressure (P .001), compared to the Boussignac valve. In all measurements the Boussignac valve showed higher than imposed CPAP level (P .001). In ICU subjects the high-flow mask had lower swing than the Boussignac valve (P = .03) with similar PaO2 increase. CONCLUSIONS: High-flow air-entrainment mask showed the best performance in human subjects. During high flow demand, the Boussignac valve delivered lower than expected FIO2 and showed higher dynamic hyper-pressurization than the air-entrainment masks.