Aerosol Delivery through Nasal Cannulas: An In Vitro Study

Abstract

In most circumstances, a nasal route for the delivery of pulmonary aerosol medications is rarely considered; however, in specific instances, this route may be quite useful. Consider, for example, the delivery of aerosol treatments during humidified high-flow nasal cannula use in pediatric critical care, or continuous aerosol delivery via cannula for medications with short durations of action. The goal of this study was to evaluate the potential for delivering aerosols via nasal cannula through in vitro studies of aerosol output and size. The system utilized for testing included an Aerogen Solo nebulizer downstream of a heater/humidifier system, followed by a nasal cannula and an aerosol collection apparatus. Adult, pediatric, and infant cannulas were tested with and without an inhalation-only breathing simulator. The cannulas were driven by 3 lpm (50 psig) oxygen flows. Dose quantification was performed using radioisotope techniques. Total cannula output and system losses were measured. Aerosol size measurements were made from the nebulizer, from the heating tube, and from the prongs of the adult and pediatric cannulas, using laser-diffraction techniques. Total cannula output ranged from 8.4-25.1% and 18.6-26.9% of loaded dose, without and with the addition of inhalation flows. Volume median diameters were 2.2 +/- 0.2 microm from the adult cannula and 1.9 +/- 0.3 microm from the pediatric cannula. Ninety percent of the aerosol volume was in sizes smaller than 4.2 +/- 0.4 microm (adult) and 3.8 +/- 0.5 microm (pediatric). System losses were highest in the nebulizer-humidifier connectors, heated tube, and humidifier. Losses in the nebulizer were very low (2.2-3.5%). This study demonstrates that aerosols can be efficiently delivered through a humidified high-flow nasal cannula system. Further study is required to determine if this route is viable for pulmonary delivery.

High-Flow Nasal Cannula and Aerosolized β Agonists for Rescue Therapy in Children With Bronchiolitis: A Case Series

“…Another in vitro study demonstrated that 18 -26% of the medication dose was delivered using a pediatric nasal cannula, and the authors concluded that aerosolized medications can be effectively delivered via HFNC. 18 In conclusion, although many in vitro studies exist, few clinical reports of aerosolized bronchodilator administration via HFNC and the Aerogen Solo exist. We report 5 cases of infants with bronchiolitis who were given ␤-agonist bronchodilators via HFNC and the Aerogen Solo.…”

Aerosol Therapy During Noninvasive Ventilation or High-Flow Nasal Cannula

“…The goal of the study by Bhashyam et al 30 was to evaluate the potential for delivering aerosols by a nasal cannula by in vitro studies of aerosol output and particle size. They evaluated a mesh nebulizer placed downstream of a heated-humidification system and a nasal cannula.…”

Comparison of HFNC, bubble CPAP and SiPAP on aerosol delivery in neonates: An in‐vitro study

“…The first study was conducted by Bhashyam et al (2008), researchers at the University of Pittsburgh in Pennsylvania. This was an in-vitro study of aerosol size and output designed to evaluate the possibility of delivering aerosols through nasal cannula.…”

“…While research comparing aerosol drug delivery through HFNC, bubble CPAP, and SiPAP is lacking, only two studies have assessed the effectiveness of aerosol drug delivery through HFNC (Ari et al, 2011;Bhashyam et al, 2008). Moreover, only one study has compared aerosol delivery through two different CPAP systems, yet that study included V-CPAP and B-CPAP (Zweifel, 2010).…”

“…Bhashyam et al (2008) examined the aerosol deposition in HFNC, using infant, pediatric, and adult size cannulas and found that the total drug output ranged from 8.4 ± 2.4% (without using a Harvard lung) to 18.6 ± 4.0% (with a Harvard lung). Their study used the same type of mesh nebulizer as this study.…”