Mechanical ventilation with heliox in an animal model of acute respiratory distress syndrome.
BACKGROUND
Heliox has a lower density and higher diffusion capacity compared to oxygen-in-air. We hypothesized that heliox ventilation allows for a reduction in minute volume ventilation and inspiratory pressures needed for adequate gas exchange in an animal model of an acute lung injury.


METHODS
After intratracheal instillation of lipopolysaccharide (10 mg/kg), adult rats were randomized to ventilation with either a gas mixture of helium/oxygen (50:50%) or oxygen/air (50:50%). They were mechanically ventilated according to the ARDSnet recommendations with tidal volumes of 6 ml/kg and monitored with a pneumotachometer. Bronchoalveolar lavage fluid was analyzed for markers of lung injury, and embedded lung sections were histologically scored for lung injury.


RESULTS
Heliox limited the increase in driving pressures needed to achieve preset tidal volumes, with a concomitant decrease in loss of compliance. Heliox did neither allow for reduced minute volume ventilation in this model nor improve gas exchange. Also, heliox did not reduce lung injury.


CONCLUSIONS
Heliox modestly improved respiratory mechanics but did not improve lung injury in this rat model of acute respiratory distress syndrome.
Laboratory of Experimental Intensive Care and Anaesthesiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105 AZ, the Netherlands, c.j.beurskens@amc.nl.
Charlotte J
CJ
Beurskens
Hamid
H
Aslami
Friso M
FM
de Beer
Joris Jth
JJ
Roelofs
Margreeth B
MB
Vroom
Nicole P
NP
Juffermans