Aerosol Delivery Through Adult High Flow Nasal Cannula With Heliox and Oxygen

Heliox (helium-oxygen mixture) has been shown to reduce turbulence and improve aerosol delivery in a range of clinical settings. We questioned whether heliox as compared with oxygen via high-flow nasal cannula (HFNC) would affect aerosol delivery. We hypothesized that heliox would have a significant effect on aerosol delivery as compared with oxygen with both quiet and distressed breathing patterns.

A vibrating mesh nebulizer was placed at the inlet of a humidifier via HFNC with small adult cannula distal to the heated-wire circuit with prongs placed into simulated nares with a T-shaped trap and absolute filter connected to a breath simulator set to adult quiet and distressed breathing parameters. Albuterol sulfate (0.083% 2.5 mg/3 mL) was aerosolized with heliox (80:20) and oxygen (100%) at 10, 30, and 50 L/min. Drug eluted from the filter was assayed with UV spectrophotometry (276 nm). Descriptive statistics, Kruskal-Wallis test, and Mann-Whitney U test were used for data analysis. P < .05 was considered statistically significant.

Increasing flows with heliox and oxygen significantly decreased percentage inhaled dose (inhaled dose) of aerosol with a quiet breathing pattern (P = .02 and P = .030, respectively). In contrast, with a distressed breathing pattern, inhaled dose at 10 L/min was lower than at 30 and 50 L/min (P = .009 and P = .01, respectively) with both oxygen and heliox (P = .009 and P = .009, respectively). Despite a trend to higher aerosol deposition with heliox versus oxygen, the differences were not significant.

With a distressed breathing pattern, aerosol delivery was greater at 30 and 50 L/min than with a quiet breathing pattern. Trends toward higher inhaled dose with heliox during HFNC were not significant.