Clinical Study Heliox Improves Carbon Dioxide Removal during Lung Protective Mechanical Ventilation Charlotte J. Beurskens, 1,2 Daniel Brevoord, 1,3 Wim K. Lagrand, 2 Walter M. van den Bergh, 4 Margreeth B. Vroom, 2 Benedikt Preckel, 1,3 Janneke Horn, 4 and Nicole P. Juffermans 1,4 1 Laboratory of Experimental Intensive Care and Anaesthesiology (LEICA), Academic Medical Center, University of Amsterdam, Room M0–210, Meibergdreef 9, 1105 AZ Amsterdam, he Netherlands 2 Department of Intensive Care, Academic Medical Center, University of Amsterdam, Room M0–210, Meibergdreef 9, 1105 AZ Amsterdam, he Netherlands 3 Department of Anaesthesiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, he Netherlands 4 Department of Intensive Care, University Medical Center, Hanzeplein 1, 9713 GZ Groningen, he Netherlands Correspondence should be addressed to Charlotte J. Beurskens; c.j.beurskens@amc.nl Received 24 July 2014; Revised 16 November 2014; Accepted 17 November 2014; Published 7 December 2014 Academic Editor: Robert Boots Copyright © 2014 Charlotte J. Beurskens et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction. Helium is a noble gas with low density and increased carbon dioxide (CO 2 ) difusion capacity. his allows lower driving pressures in mechanical ventilation and increased CO 2 difusion. We hypothesized that heliox facilitates ventilation in patients during lung-protective mechanical ventilation using low tidal volumes. Methods. his is an observational cohort substudy of a single arm intervention study. Twenty-four ICU patients were included, who were admitted ater a cardiac arrest and mechanically ventilated for 3 hours with heliox (50% helium; 50% oxygen). A ixed 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 signiicance set at  < 0.017. Results. During heliox ventilation, respiratory rate decreased (25 ± 4 versus 23 ± 5 breaths min −1 ,  = 0.010). Minute volume ventilation showed a trend to decrease compared to baseline (11.1 ± 1.9 versus 9.9 ± 2.1 L min −1 ,  = 0.026), while reducing PaCO 2 levels (5.0 ± 0.6 versus 4.5 ± 0.6 kPa,  = 0.011) and peak pressures (21.1 ± 3.3 versus 19.8 ± 3.2 cm H 2 O,  = 0.024). Conclusions. Heliox improved CO 2 elimination while allowing reduced minute volume ventilation in adult patients during protective mechanical ventilation. 1. Introduction Helium is an inert gas with lower density than air [1], allowing for less turbulent low through airways and leading to lower airway resistance. As a result, during mechanical ventilation with a helium/oxygen mixture (heliox), lower driving pressures are needed to distribute oxygen to the distal alveoli compared to ventilation with oxygen [2]. Furthermore helium is known for its increased difusion capacity of carbon dioxide (CO 2 ), which in addition might facilitate ventilation. Due to these properties, there may be a rationale to use heliox in patients with severe pulmonary disease with respiratory failure whose protective mechanical ventilation with low tidal volumes is not feasible due to the development of respiratory acidosis, for example, in acute respiratory distress syndrome (ARDS) or chronic obstructive pulmonary disease (COPD). Nowadays, the use of heliox is clinically applied using high frequency ventilation in pediatric patients [3, 4] and in patients with high airway resistance due to severe asthma or COPD, most oten in children [5, 6]. Clinical data on adult patients during conventional mechanical ventilation are limited. he aim of this study was to investigate the efect of heliox on gas exchange as part of a safety and feasibility study on Hindawi Publishing Corporation Critical Care Research and Practice Volume 2014, Article ID 954814, 5 pages http://dx.doi.org/10.1155/2014/954814