Impact of endotracheal tube shortening on work of breathing in neonatal and pediatric in vitro lung models

BACKGROUND: Work of breathing accounts for a significant proportion of total oxygen consumption in neonates and infants. Endotracheal tube inner diameter and length significantly affect airflow resistance and thus work of breathing. While endotracheal tube shortening reduces endotracheal tube resistance, the impact on work of breathing in mechanically ventilated neonates and infants remains unknown. AIM: The objective of this in vitro study was to quantify the effect of endotracheal tube shortening on work of breathing in simulated pediatric lung settings. We hypothesized that endotracheal tube shortening significantly reduces work of breathing. METHODS: We used the Active-Servo-Lung 5000 to simulate different clinical scenarios in mechanically ventilated infants and neonates under spontaneous breathing with and without pressure support. Endotracheal tube size, lung resistance, and compliance, as well as respiratory settings such as respiratory rate and tidal volume were weight and age adapted for each lung model. Work of breathing was measured before and after maximal endotracheal tube shortening and the reduction of the daily energy demand calculated. RESULTS: Tube shortening with and without pressure support decreased work of breathing to a maximum of 10.1% and 8.1%, respectively. As a result, the calculated reduction of total daily energy demand by endotracheal tube shortening was between 0.002% and 0.02%. CONCLUSION: In this in vitro lung model, endotracheal tube shortening had minimal effects on work of breathing. Moreover, the calculated percentage reduction of the total daily energy demand after endotracheal tube shortening was minimal