A review of the use of heliox in the critically ill.

Heliox, a mix of oxygen and helium, has a number of potential medical applications resulting from its relatively lower density. This paper reviews the physics underlying its utility and considers the evidence for its use. While there are studies that support its role, particularly in patients with exacerbations of asthma and chronic obstructive pulmonary disease (COPD), the data are inconclusive.