To obtain a gas mixture which is useful for treating or preventing the acute asthma or the chronic obstructive bronchopneumopathy of men or animals, and so on, by mixing helium with oxygen in a specific ratio and then packaging the mixture at a specified high pressure.

This gas mixture comprises 63.1 to 69.9 vol.% of helium and the remainder of oxygen, and is packaged at a pressure of ≥2 bar. The gas mixture may be used for preparing a medicinal preparation comprising the gas mixture and/or a propellant gas and a liquid and/or solid particles containing a therapeutically effective compound (for example, β2-mimetic), in the form of an aerosol. The gas mixture can reduce the fatigue of the respiratory muscle of a patient.