Validation of the newborn larynx modeling with aerodynamical experimental data

Assessment of high-flow nasal cannula efficacy in humidification of infant airways: A computational fluid dynamics approach

INTRODUCTION

High-flow nasal cannula therapy has garnered significant interest for managing pathologies affecting infants' airways, particularly for humidifying areas inaccessible to local treatments. This therapy promotes mucosal healing during the postoperative period. However, further data are needed to optimize the use of these devices. In vivo measurement of pediatric airway humidification presents a challenge; thus, this study aimed to investigate the airflow dynamics and humidification effects of high-flow nasal cannulas on an infant's airway using computational fluid dynamics.

METHODS

Two detailed models of an infant's upper airway were reconstructed from CT scans, with high-flow nasal cannula devices inserted at the nasal inlets. The airflow was analyzed, and wall humidification was modeled using a film-fluid approach.

RESULTS

Air velocities and pressure were very high at the airway inlet but decreased rapidly towards the nasopharynx. Maximum relative humidity-close to 100%-was achieved in the nasopharynx. Fluid film development along the airway was heterogeneous, with condensation primarily occurring in the nasal vestibule and larynx.

CONCLUSION

This study provides comprehensive models of airway humidification, which pave the way for future studies to assess the impact of surgical interventions on humidification and drug deposition directly at operative sites, such as the nasopharynx or larynx, in infants.

The very first cry: a multidisciplinary approach toward a model

OBJECTIVES

In previous work, we showed that a rigid larynx-like geometry can generate a sound by itself. However, very little is known about the exact mechanisms and control of the larynx during the first cry of life. The goal of this work was to understand how the very first cry is generated.

METHODS

Simultaneous high-speed imaging and sound recording on 2 excised 38-week term human fetus larynges were performed. The behaviors of the vocal folds and the false vocal folds were studied separately. The behavior of the vocal folds after resection of the supraglottic structures was also analyzed. A comparative acoustic analysis of the first cry and of the sound generated by the excised organs was performed.

RESULTS

Our data showed that the vocal folds in a larynx with the pressure conditions of the first cry do not generate sound themselves, but induce aerodynamic conditions leading to vibrations of other parts of the larynx.

CONCLUSIONS

The similarities between the sound generated by an excised larynx and the first cry suggest a lack of neurologic control of the larynx during production of the first cry. A model-algorithm is proposed.