Heliox Improves Carbon Dioxide Removal during Lung Protective Mechanical Ventilation

Abstract

Introduction. Helium is a noble gas with low density and increased carbon dioxide (CO2) diffusion capacity. This allows lower driving pressures in mechanical ventilation and increased CO2diffusion. We hypothesized that heliox facilitates ventilation in patients during lung-protective mechanical ventilation using low tidal volumes.Methods. This is an observational cohort substudy of a single arm intervention study. Twenty-four ICU patients were included, who were admitted after a cardiac arrest and mechanically ventilated for 3 hours with heliox (50% helium; 50% oxygen). A fixed protective ventilation protocol (6 mL/kg) was used, with prospective observation for changes in lung mechanics and gas exchange. Statistics was by Bonferroni post-hoc correction with statistical significance set atP<0.017.Results. During heliox ventilation, respiratory rate decreased (25±4versus23±5breaths min−1,P=0.010). Minute volume ventilation showed a trend to decrease compared to baseline (11.1±1.9versus9.9±2.1 L min−1,P=0.026), while reducing PaCO2levels (5.0±0.6versus4.5±0.6 kPa,P=0.011) and peak pressures (21.1±3.3versus19.8±3.2 cm H2O,P=0.024).Conclusions. Heliox improved CO2elimination while allowing reduced minute volume ventilation in adult patients during protective mechanical ventilation.