Thinner Catheter Use During Lisa can Minimize Airway Resistance in Extremely Preterm Infants

Delivering surfactant through thin catheters, known as minimal-invasive surfactant therapy (MIST) or less invasive surfactant administration (LISA), is a common procedure. However, the impact of different catheter sizes on tracheal resistance in extremely low gestational-age newborns (ELGANs) remains unclear. A new study examined the effect of 3.5, 5, and 6 French catheters on airway resistance in ELGANs (23-28 weeks gestational age) during LISA.

The calculations utilized Hagen-Poiseuille's law alongside computational fluid dynamics (CFD) simulations in 3D airway models derived from MRI to provide more accurate results.

It was observed that the French catheters reduced the cross-sectional area of the tracheal entrance by 13-53%. Hagen-Poiseuille's law predicted resistance increases of 1.5-4.5 times for 23-week ELGANs and 1.3-2.6 times for 28-week ELGANs. CFD simulations revealed even more significant resistance increases (3.4-85.1 times for 23 weeks and 1.1-3.5 times for 28 weeks). The higher resistance was attributed to the narrow remaining lumen at the glottis and cricoid, leading to turbulent airflow, which Hagen-Poiseuille did not predict.

From the findings, it was concluded that:

• Thicker catheters significantly raise tracheal resistance in ELGANs during LISA. 
• To minimize airway resistance, thinner catheters are recommended, especially for the most immature ELGANs. 
• While thinner catheters may make the procedure challenging, this must be weighed against the risk of increased airway resistance and work of breathing––which could contribute to LISA failure.
• The findings underscore the importance of catheter size in clinical settings.

Source: Gunatilaka CC, Xiao Q, Bates AJ, et al. Frontiers in Pediatrics. 2024 Sep 17;12:1352784.