Effects of heliox as carrier gas on ventilation and oxygenation in an animal model of piston-type HFOV: A crossover experimental study

Abstract

Objective: This study aimed to compare gas exchange with heliox and oxygen-enriched air during piston-type high-frequency oscillatory ventilation (HFOV). We hypothesized that helium gas would improve both carbon dioxide elimination and arterial oxygenation during piston-type HFOV.Method: Five rabbits were prepared and ventilated by piston-type HFOV with carrier 50% helium/oxygen (heliox50) or 50% oxygen/nitrogen (nitrogen50) gas mixture in a crossover study. Changing the gas mixture from nitrogen50 to heliox50 and back was performed five times per animal with constant ventilation parameters. Arterial blood gas, vital function and respiratory test indices were recorded.Results: Compared with nitrogen50, heliox50 did not change PaCO2when stroke volume remained constant, but significantly reduced PaCO2after alignment of amplitude pressure. No significant changes in PaO2were seen despite significant decreases in mean airway pressure with heliox50 compared with nitrogen50.Conclusion: This study demonstrated that heliox enhances CO2elimination and maintains oxygenation at the same amplitude but with lower airway pressure compared to air/O2mix gas during piston-type HFOV. © 2010 Fakhraddin et al; licensee BioMed Central Ltd.