Heliox versus oxygen for nebulized aerosol therapy in children with lower airway obstruction

To compare the distribution of an inhaled labeled radioaerosol (diethilenotriaminopenthacetate labeled with technetium-99m) when either oxygen or heliox was used as a gas vehicle of nebulization. Randomized, double-blind, controlled study. Nuclear medicine imagining department of tertiary university-affiliated hospital. Twenty children (5-15 yrs old) with confirmed diagnosis of chronic lower airway obstruction and referred for a ventilatory scintigraphy study. Patients were randomized to use either the heliox mixture (helium/oxygen, 80:20) or oxygen during the scintigraphy study. The maximal cumulative irradiation absorbed by the lungs and the slope of the curve of the cumulative irradiation incorporated into the lungs over the time were used to compare the groups. Student's t -test, one-way analysis of variance, chi-square test, and Fisher's exact test were used to compare the groups. Ten patients were allocated to each group with no differences in demographic data, main diagnosis, and pulmonary function tests. Ninety-five percent of the particles produced by both gases had a diameter