The oxygen cylinder contents gauge on the tank that nurse lee brings to the child's bedside shows nearly three-quarters full. This represents a large volume of oxygen. The contents could not go down as fast as is shown here. Even if she took the regulator off and opened the cylinder all the way (which would make an ear-splitting noise) it wouldn't go down that fast. An H tank (which is the size shown in the film)
holds 7100 cubic liters of oxygen. Oxygen being given with oxygen mask could not drain the tank shown in that short time.