Helium administration is more effective during piston-driven high-frequency oscillatory ventilation than conventional mechanical ventilation in a rabbit model

Abstract

Background Low-molecular-weight gases such as helium are more likely to form laminar flows. Using helium-oxygen mixtures instead of nitrogen-oxygen mixtures during mechanical ventilation has been shown to accelerate carbon dioxide (CO2) excretion. Helium-oxygen mixtures have been used with mechanical ventilator settings such as high-frequency oscillatory ventilation (HFOV) and conventional mechanical ventilation (CMV). However, to the best of our knowledge, studies have not been conducted to determine the optimal ventilator setting for the promotion of CO2 excretion when helium is administered. This study aimed to compare the efficacy of using helium-oxygen gas mixtures between pressure-controlled CMV and piston-driven HFOV in rabbit models. CO2 transition was evaluated using blood gas analysis performed during and after helium administration. Experimental data were analyzed using parametric statistical methods. A repeated measures analysis of variance was used to compare CO2 excretion between HFOV and CMV. Results There was no statistically significant difference in the partial pressure of CO2 (PaCO2) or oxygen (PaO2) values before or after helium administration. Compared with pre-helium administration, PaCO2 values during helium administration were decreased under both CMV and piston-driven HFOV. Moreover, the PaCO2 transition during helium administration while using piston-driven HFOV was shown to be statistically significantly different (P < 0.001). Conclusions This study demonstrated that helium enhances CO2 elimination more significantly during piston-driven HFOV compared with that in CMV in rabbit models with normal lungs. With further study and clinical trials, these results imply that the use of HFOV while using a helium-oxygen mixture may improve CO2 excretion.