Development of Aerosol Drug Delivery with Helium Oxygen Gas Mixtures

Abstract

Aerosol drug delivery using helium-oxygen gas mixtures (heliox) is considered in terms of flow physics, atomization, and aerosol mechanics. Theoretical considerations are then related to past studies of the physiological effects of the inhalation of heliox and its potential use as a drug delivery medium. Past clinical trials of heliox investigating this use are reviewed and technical recommendations made for its successful development. It is proposed that improved peripheral lung drug delivery with heliox is highly dependent on proper administration, especially the inclusion of proper reservoir system for the gas.

The Effects of Heliox on the Output and Particle-Size Distribution of Salbutamol Using Jet and Vibrating Mesh Nebulizers

“…The use of a reservoir system, ensuring Heliox inhaled by a patient is not diluted by entrained air, appears crucial to its effectiveness as a carrier gas for bronchodilator aerosols (6) . It has been hypothesised that the lower density of Heliox would result in less turbulent flow and, thus, improve drug delivery to the lungs in patients with airways obstruction.…”

“…As argued by Corcoran and Gamard, the increased respiratory rate associated with inhalation with Heliox may reduce the settling time for these particles. However, the larger tidal volumes breathed when Heliox is inhaled combined with less momentum loss in the upper airway is likely to deliver drug aerosols deeper into the lung (6) . In our study, we found a significantly greater dose of drug was available for inhalation when the vibrating mesh nebuliser was used with Heliox compared to air.…”

“…The lower density of Heliox relative to air means that higher flows of Heliox are required to produce an aerosol of similar size to that produced by the same flow of air (6) .…”

“…However, clinical trials where Heliox has been used in an attempt to improve aerosol drug delivery have produced variable results (5) . Some of this variability may be explained by dilution of Heliox with air when patients inhale (6) . Jet nebulisers are driven by a pressurised gas.…”

“…Interpretation of clinical trials using Heliox for nebulised drug delivery is also hindered by the lack of data on the effect of the gas on the particle size of the drug aerosol. To allow informed interpretation of drug delivery studies, detailed information on the delivery system including the use of reservoir systems (6) , particle size analysis of the drug aerosol (14) and the effect of breathing pattern on drug likely to be inhaled (15) are essential.…”