Deposition studies of aerosol delivery by nasal cannula to infants

Abstract

Aim Nasal cannulas are used to provide oxygen support for infants and have been considered as a means for delivering aerosols to the lungs. To measure mucociliary clearance in the lungs of infants with congenital heart defects, we delivered radiopharmaceutical aerosols via a nasal cannula. Here we report on the pulmonary and nasal deposition of these aerosols. Method A total of 18 infants (median age = 26 days; quartiles = 11‐74 days) performed clearance measurements soon before or after corrective cardiac surgery. The regional aerosol deposition was assessed using gamma camera imaging. Results Cannula flow rate significantly affected pulmonary dosing. Flow rates useful for oxygen support were associated with low pulmonary deposition (2 L/min; mean, 4.5% of deposited dose; range, 2%‐9%; n = 7) and high nasal deposition. Much lower cannula flow rates increased the pulmonary deposition (0.2 L/min; mean, 33.5% of deposited dose; range, 15%‐51%; n = 5; P = 0.005 vs 2 L/min). The ratio of nose/lung dosing was approximately 26:1 at 2 L/min and 2:1 at 0.2 L/min. Bench studies demonstrated cannula output rates of 10.2 ± 1.7% (2 L/min) and 3.3 ± 0.4% (0.2 L/min) of the loaded nebulizer dose during a 2‐minute delivery. Combining in vitro and in vivo results, we estimate that 0.46% of the loaded nebulizer dose reaches the lungs at 2 L/min vs 1.10% at 0.2 L/min during a 2‐minute delivery. Conclusion With the delivery system used here, pulmonary aerosol delivery via nasal cannula was very inefficient at the flow rates required to provide oxygen support. Even at low flows, nasal deposition was substantial and local toxicity must be considered.

The Clinical Impact of Flow Titration on Epoprostenol Delivery via High Flow Nasal Cannula for ICU Patients with Pulmonary Hypertension or Right Ventricular Dysfunction: A Retrospective Cohort Comparison Study

“…Multiple in vitro and in vivo scintigraphy studies have investigated influential factors of trans-nasal aerosol delivery and the ratio of gas flow to patient inspiratory flow was found to play a key role [10][11][12][13][14][15]. However, little evidence is available on its clinical impact.…”

In vitro comparison between inspiration synchronized and continuous vibrating mesh nebulizer during trans-nasal aerosol delivery

“…Gas flow setting during HFNC and patient's breathing pattern (quiet vs distressed breathing) have been identified as significant influential factors during trans-nasal aerosol delivery [13][14][15][16][17][18], as such, the two factors as well as nebulizer placement were also compared in our study.…”

In vitro comparison of unit dose vs infusion pump administration of albuterol via high‐flow nasal cannula in toddlers

“…The gas flow rate has been inversely correlated to aerosol delivery efficiency via HFNC . However, reducing flow for prolonged periods may impact oxygenation and work of breathing .…”

“…The gas flow rate has been inversely correlated to aerosol delivery efficiency via HFNC. 18,19 However, reducing flow for prolonged periods may impact oxygenation and work of breathing. 16 We hypothesize that delivery of a unit dose of high-concentrated albuterol in a small total volume (1-2 mL), requiring 3 to 6 minutes 18 could deliver a similar or higher inhaled dose than the same administered dose via infusion pump over a longer period of time.…”