Category
Applied
Description
Computational models were used to investigate the flow in the upper airway during high-velocity therapy delivered via a single-prong or a dual-prong cannula geometry. A temporally varying boundary condition was used to apply a realistic breathing cycle to the base of the trachea. The patient mouth was “closed” to specific percentages by modifying the cross sectional area of a plane in the patient mouth. The total amount of CO2 inhaled, which should be minimized, was collected as a measure of therapy effectiveness. The mass CO2 inhaled was calculated by subtracting the mass of CO2 present in the airway at the end of the inspiratory phase from the mass of CO2 present in the airway at the end of the expiratory phase for each breath cycle. The calculated values of mass CO¬2¬ inhaled were averaged over numerous breath cycles for each model. It was found that, in the scenarios simulated, a single-prong cannula geometry more effectively flushed CO2 from the airway than a standard dual-prong geometry, given that all other factors were held constant. A completely closed mouth resulted in a greater performance discrepancy between cannula geometries than a 20% open mouth. Further study could include similar analyses for a variety of airway geometries to provide a more in-depth understanding of the generalizability of these conclusions.
CO2 Washout Performance of Single-Prong and Dual-Prong High-Velocity Therapy
Applied
Computational models were used to investigate the flow in the upper airway during high-velocity therapy delivered via a single-prong or a dual-prong cannula geometry. A temporally varying boundary condition was used to apply a realistic breathing cycle to the base of the trachea. The patient mouth was “closed” to specific percentages by modifying the cross sectional area of a plane in the patient mouth. The total amount of CO2 inhaled, which should be minimized, was collected as a measure of therapy effectiveness. The mass CO2 inhaled was calculated by subtracting the mass of CO2 present in the airway at the end of the inspiratory phase from the mass of CO2 present in the airway at the end of the expiratory phase for each breath cycle. The calculated values of mass CO¬2¬ inhaled were averaged over numerous breath cycles for each model. It was found that, in the scenarios simulated, a single-prong cannula geometry more effectively flushed CO2 from the airway than a standard dual-prong geometry, given that all other factors were held constant. A completely closed mouth resulted in a greater performance discrepancy between cannula geometries than a 20% open mouth. Further study could include similar analyses for a variety of airway geometries to provide a more in-depth understanding of the generalizability of these conclusions.
