Nasal versus oral aerosol delivery to the "lungs" in infants and toddlers

Abstract

Objectives: The oral route has been considered superior to the nasal route for aerosol delivery to the lower respiratory tract (LRT) in adults and children. However, there are no data comparing aerosol delivery via the oral and nasal routes in infants. The aim of this study was to compare nasal and oral delivery of aerosol in anatomically correct replicas of infants' faces containing both nasal and oral upper airways.

Methods: Three CT-derived upper respiratory tract ("URT") replicas representing infants/toddlers aged 5, 14 and 20 months were studied and aerosol delivery to the "lower respiratory tract" (LRT) by either the oral or nasal route for each of the replicas was measured at the "tracheal" opening. A radio-labeled (99mDTPA) normal saline solution aerosol was generated by a soft-mist inhaler (SMIRespimat® Boehringer Ingelheim, Germany) and aerosol was delivered via a valved holding chamber (Respichamber® TMI, London, Canada) and an air-tight mask (Unomedical, Inc., McAllen, TX). A breath simulator was connected to the replicas and an absolute filter at the "tracheal" opening captured the aerosol representing "LRT" dose. Age-appropriate mask dimensions and breathing patterns were employed for each of the airway replicas. Two different tidal volumes (V_t ) were used for comparing the nasal versus oral routes.

Results: Nasal delivery to the LRT exceeded that of oral delivery in the 5- and 14-month models and was equivalent in the 20-month model. Differences between nasal and oral delivery diminished with "age"/size. Similar findings were observed with lower and higher tidal volumes (V_t ).

Conclusion: Nasal breathing for aerosol delivery to the "LRT" is similar to, or more efficient than, mouth breathing in infant/toddler models, contrary to what is observed in older children and adults. Pediatr Pulmonol. 2015; 50:276-283. © 2014 Wiley Periodicals, Inc.

Keywords: aerosol delivery; airway models; inhaled dose; leak; pediatric.