| Summary: | The current treatment to cure neonatal Respiratory Distress Syndrome (RDS) entails several risks for the preterm infant. This treatment requires the intubation of the patient and the administration of an intratracheal bolus of surfactant. The current trend in neonatology is towards the development of a more gradual and less invasive treatment. In this regard, administering aerosolized surfactant in conjunction with a non-invasive respiratory support is a promising technique.
This thesis has been developed in the experimental and numerical fields. Firstly, an experimental or in vitro study of an existing nebulizer was carried out to determine the feasibility of generating surfactant aerosols above the vocal chords in preterm infants. In addition, a mathematical model that predicts the behavior of the aerosol within the neonatal physical model of the trachea was constructed. Finally, some guidelines have been proposed in order to improve the design of this nebulizer.
The experimental evaluation of the nebulizer, that is an inhalation catheter, has been made by means of a high speed camera, a pneumotach, an aerodynamic particle sizer, a precision balance and a hot-wire anemometer. Moreover, two physical models of the neonatal upper airways have been manufactured by rapid prototyping; one of them represents the neonatal trachea whereas the other one represents the respiratory system from the trachea to the third generation. An experimental deposition study has been carried out within these physical models, placing the aerosol generation tip at the beginning of the trachea. Experimental results show that surfactant aerosolization seems to be feasible to treat neonatal RDS using an inhalation catheter.
Regarding the modeling, a mathematical model that predicts the behavior of the aerosol produced by the inhalation catheter within the neonatal model of the trachea has been constructed. This mathematical model has been validated making a comparison between numerical and experimental results. This model has allowed for the making of a numerical study on the influence of the aerosol characteristics, such as the particle diameter or the surfactant mass flow rate, in the deposition of the particles.
After analyzing the numerical and experimental results, some guidelines have been recommended to improve the design of this inhalation catheter and, consequently, the surfactant administration efficiency in neonates.
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