PubMed:29125912 JSONTXT

An In Vitro Examination of the Effects of Altitude on Dry Powder Inhaler Performance. BACKGROUND: The effects of altitude on dry powder inhaler (DPI) performance remain understudied. As existing standardized testing methodologies do not consider altitude, inhalation devices may be used in environments in which their performance has not been sufficiently characterized. METHODS: Six DPIs spanning a range of device resistances were examined in vitro in an environmental chamber mimicking a high-altitude environment equivalent to an altitude of 4200 m, with controls established at an altitude of 700 m. Deposition and size distribution data were quantified by using an Alberta Idealized Throat coupled to a Next-Generation Impactor, operated by using a square inhalation profile. Controls were established for two cases, one with a standard pressure drop and the other with a minimal efficacious flowrate. Experiments at simulated altitude were performed first by using a matched volumetric flowrate and second with a matched pressure drop, corresponding to values obtained in the controls. In vitro results were input into a lung deposition model to examine the relationship between particle-size distributions, inhalation flowrates, and regional deposition in the respiratory tract. RESULTS AND CONCLUSIONS: Simulated altitude caused statistically significant effects in some DPIs, but effects were variable, device dependent, and relatively minor. Medium-high resistance devices were more affected by the flowrate used to establish the control than by any effects of altitude. Patients able to generate sufficient inspiratory efforts can expect relatively consistent device performance at altitudes up to 4200 m for the devices examined here.