Impact of endotracheal tube biofilm and respiratory secretions on airway resistance and mechanics of breathing in a neonatal lung model

Abstract

Endotracheal tube (ETT) obstruction from biofilm formation is a theoretical risk for intubated preterm neonates. The objective of this study is to determine the impact of ETT biofilm on ETT resistance and minute ventilation in a neonatal respiratory model. Postextubation 2.5- and 3.0-mm ETTs from ventilated preterm infants were matched with unused control ETTs. The pressure gradient across the ETT was measured at set flow rates and converted to airway resistance. Spontaneous breathing tests (SBTs) were performed using a virtual patient model and were considered “passed” if minute ventilation of patient ETTs was greater than 60% of control ETTs. Twenty-four 2.5-mm ETTs and sixteen 3.0-mm ETTs were analyzed. In both patient and control ETTs, as flow rate increases, the pressure gradient across the ETT also increases in a linear fashion. Resistance to flow in patient ETTs was statistically different from matched control ETTs ( P < 0.001), and patient ETTs had 19.9 cmH2O·l−1·sec−1 greater resistance than control ETTs. SBTs were performed in 27 of 40 ETTs. Twenty-six ETTs “passed” an SBT. In one obstructed 3.0-mm ETT, SBT measurements were unobtainable. The clinical impact of ETT biofilm as measured by a SBT appears to be minimal for the majority of patients in our study group. In 1 out of 27 ETTs, the presence of a biofilm significantly altered resistance to airflow and resulted in a failed SBT. Gas flow rate and ETT size had a greater impact on resistance to airflow and minute ventilation than ETT biofilm in this study sample. NEW & NOTEWORTHY This is the first study to our knowledge to characterize the impact of endotracheal tube (ETT) biofilm and respiratory secretions on resistance to airflow in a neonatal ETT using a simulation neonatal lung model. Results show that the clinical impact of ETT biofilm is minimal for the majority of patients in our study group, and ETT obstruction from biofilm is an uncommon cause of respiratory decompensation in a preterm neonate.