High-frequency jet ventilation using a helium-oxygen mixture

The physiological basis for the use of helium relates to the relationship d escribed by Poiseuille. During turbulent gas flow, the factors determining the resistance to flow include the density of gas as well as the length and the radius of a tube. While it may not be possible to readily change the l atter two, altering the density of the gas is possible by using helium inst ead of nitrogen. A helium-oxygen combination has been used most commonly to improve air exchange in patients with upper airway obstruction. Anecdotal reports also suggest the beneficial effects of helium during mechanical ven tilation in patients with status asthmaticus, hyaline membrane disease, and other pulmonary parenchymal disorders. To date, the clinical reports have utilized helium only with conventional mechanical ventilation. We present a child whose progressive respiratory failure was treated by using high-freq uency jet ventilation with a combination of helium and oxygen. The techniqu es for the delivery of helium and oxygen through the jet ventilator are dis cussed.