Objective: To determine the prevalence, size, and factors affecting tracheal tube (TT) leak in clinical practice and their influence on the displayed tidal volume (Vt) in ventilated newborn infants using uncuffed TTs. Monitoring of Vt is important for implementation of lung-protective ventilation strategies but becomes meaningless in the presence of large TT airleaks.
Design: Retrospective clinical study.
Setting: Neonatal intensive care unit.
Patients: Patient records of 163 neonates ventilated with Babylog 8000 for ≥ 5 hrs with a median (range) gestation age of 31.1 wks (23.3-41.9 wks) and a median birth weight of 1470 g (410-4475 g) were evaluated.
Interventions: : Ventilatory settings, TT leak, and Vt were recorded every 3 hrs. The lowest, median, and highest TT leaks were noted on the day the first TT leak (>5%) occurred, the day on which TT leak peaked, and the day of extubation.
Measurements and main results: A TT leak of >5% was seen in 122 (75%) infants. Neonates with TT leak, compared with those without TT leak, had a longer duration of mechanical ventilation (p < .001), a lower gestational age (p = .004), a reduced birth weight (p = .005), and a higher prevalence of reintubation (p = .003). The greatest TT leak was seen in infants ventilated with a TT of <3-mm diameter. During the entire duration of mechanical ventilation, 42.3% of all neonates experienced at least one TT leak of >40% commonly seen on the third day of mechanical ventilation. Regression analysis showed that a TT leak of 40% indicated that the displayed Vt was underestimated by 1.2 mL/kg (about 24% of target Vt).
Conclusions: TT leak is highly variable, and TT leak of >40% with clinically relevant Vt errors occurred in nearly half of all ventilated neonates. Preterm infants of low birth weight and with small-diameter TTs ventilated for a long period were at greater risk of TT leak.