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Influences of Cannula Size and Flow Rate on Aerosol Drug Delivery Through the Vapotherm Humidified High-Flow Nasal Cannula System

Perry, Sarah A. MD1; Kesser, Kenneth C. RRT2; Geller, David E. MD3; Selhorst, Dawn M. RRT-NPS4; Rendle, John K. RRT4; Hertzog, James H. MD1,4

Pediatric Critical Care Medicine: June 2013 - Volume 14 - Issue 5 - p e250–e256
doi: 10.1097/PCC.0b013e31828a7f79
Online Laboratory Investigations

Objective: We investigated the in vitro inspired dose and particle size distribution of albuterol delivered by a vibrating mesh nebulizer through the Vapotherm (Stevensville, MD) humidified high-flow nasal cannula system.

Design: Albuterol (2.5 mg/3 mL) was delivered by an Aeroneb Solo (Aerogen, Galway, Ireland) nebulizer that was connected via adaptor proximal to the nasal cannula and downstream from the Vapotherm 2000i. Albuterol was collected onto an inspiratory filter mounted to a breath simulator programmed with age-appropriate breathing patterns. Particle sizing was completed by cascade impaction. Albuterol was quantified using ultraviolet spectrometry. Measurements were made using varying flow rates through infant, pediatric, and adult nasal cannulae.

Setting: Aerosol research laboratory.

Measurements and Main Results: The inspired dose (percent of nominal dose) for each cannula size and flow rate was 2.5%, 0.8%, 0.4%, and 0.2% for the adult cannula at 5, 10, 20, and 40 L/min, respectively; 1.2%, 0.6%, 0.1%, and 0.0% for the pediatric cannula at 3, 5, 10, and 20 L/min, respectively; and 0.6%, 0.6%, and 0.5% for the infant cannula at 3, 5, and 8 L/min, respectively. Most (62–80%) of the loaded albuterol dose accumulated within the adaptor. For each cannula size, there was a significant decrease in the inspired dose with increasing flow rates, p = 0.026 (infant), p = 0.001 (pediatric), and p < 0.001(adult). The inspired dose increased with increasing cannula size for 5, 10, and 20 L/min (p = 0.007, p < 0.001, and p = 0.005, respectively). The mass median aerodynamic diameter for all trials was less than 5 µm.

Conclusion: The amount of albuterol delivered with the Vapotherm system using this model was lower than the amount expected for a clinical response for the majority of flow rates and cannula size combinations. Further studies are needed before routine use of aerosolized albuterol through a Vapotherm high-flow system can be recommended.

1Department of Anesthesiology and Critical Care Medicine, Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE.

2Division of Biomedical Research, Nemours Children’s Clinic, Orlando, FL.

3Florida State University College of Medicine, Orlando, FL.

4Department of Respiratory Therapy, Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE.

Current address for Dr. Rendle: Department of Respiratory Therapy, Nemours Children's Hospital, Orlando, FL.

Work was performed at Aerosol Research Laboratory, Nemours Children’s Clinic, Orlando, FL.

Supported, in part, by a grant from the Nemours Foundation. A Vapotherm 2000i unit and four aerosol adaptors were donated by Vapotherm.

The authors have disclosed that they do not have any potential conflicts of interest.

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©2013The Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies