Question

Which statements are true about helium and heliox mixtures?

I. Helium is a gas that is denser than either air or oxygen.

II. Heliox decreases the effective flow resistance in patients with upper airway obstruction.

III. If you use a flow meter calibrated for oxygen to deliver a 70:30 heliox concentation, the actual flow of heliox will be 1.8 times greater than the indicated flow.

IV. Heliox can’t be administered through a mechanical ventilator.

A. I and IV only

B. II and III only

C. III and IV only

D. I and II only

Answer 1

Helium is an element which is colorless, tasteless and odorless gas, while heliox is mixture of helium gas (79%) and oxygen gas (21%) which is used as breathing gas and used to treat patient with breathing issue.

Helium is less dense than air as well as oxygen. It is around 86% less dense than air and 8 times less dense than oxygen gas. Therefore, statement I is false.

The heliox produce less resistance compared to oxygen or atmospheric air when administering through the airway of lungs, and this decreases the effort in breathing by the patients having trouble in breathing. Therefore, statement II is correct.

As the oxygen is denser than heliox and when oxygen flow meter is used to deliver the heliox, so heliox correction factor is to be considered. For 70:30 heliox, the heliox correction factor is 1.6, therefore when the oxygen flow meter read 10 L/min, it means it can deliver Heliox 16 L/min. For heliox of 80:20, the heliox correction factor is 1.8, it means, when oxygen flow meter indicate 10 L/min, so by heliox it is 18 L/min. Therefore, statement III is also very true.

Heliox can be administered through some mechanical ventilators, so option IV is also not true.

Hence, option B is more true as statement III indicating that the heliox will be delivered more when using oxygen flow meter.

Answer must be option B: II and III only