[Symptomatic helium treatment of upper and lower airway obstruction].

Since 1934 several clinical trials have been performed to investigate the effect of helium in the symptomatic treatment of upper and lower airway obstructions, especially in children. Controlled studies have only been produced during the last decade. Heliox, a mixture of helium and oxygen, has a significantly lower density than N2/O2-mixtures. This produces better flow and hence a decrease in respiratory work, improvement of distal gas exchange and theoretically less tendency to air-trapping and hyperinflation. When holding more than 40% O2 the clinical effect decreases. There are case reports of rapid subjective release, less stridor, lower respiratory rate and a normalization of hypercapnia and acidosis. Controlled studies confirm this and demonstrate a decrease in the need for intubation and mechanical ventilation. Time is bought until conventional therapy with steroids, epinephrine and beta 2-agonist inhalation works. Helium has its place in treatment of airway obstructions, but more clinical trials are needed to define the indication for symptomatic heliox treatment.