Abstract: Medical devices and methods are provided for the pulmonary delivery of a drug in heliox gas. One method comprises (a) providing a medical device which comprises an aerosolization means, a conduit means, a gas mask, and a source of heliox gas, the medical device being operable as a closed system to prevent entrainment of ambient air into an inhaled aerosol; (b) providing a drug in a liquid or dry powder form; (c) using the aerosolization means to form an aerosol of particles or droplets dispersed in heliox gas, said particles or droplets comprising the drug and said heliox gas being from said source; and (d) flowing the aerosol through the conduit means and into the gas mask secured over a patient's mouth and nose in a manner for the patient to inhale the aerosol without dilution of the aerosol with ambient air.