Figure 1From: Methods for evaluation of helium/oxygen delivery through non-rebreather facemasksNon-rebreather facemasks evaluated in the present study: a) The Hi-Ox mask, b) the Heliox21 mask, and c) the standard mask. Black arrows indicate the positions of inhalation valves, while white arrows indicate the position of exhalation valves. The dotted arrow in a) indicates the position of the anti-suffocation valve.Back to article page