Extent and incidence of endotracheal tube leakage in ventilated neonates

Monitoring of tidal volume (V_T) is important for implementation of lung-protective ventilation strategies and to reduce ventilator induced lung injury but becomes meaningless in the presence of large endotracheal tube (ET) leakages. Using Babylog 8000 ventilator, we have recently shown that (Mahmoud et al. Acta Paediatr. 2009) ET leakage >40% cause clinically relevant errors in the displayed V_T. Objective: The aim of this retrospective clinical study was to determine the extent, incidence and factors affecting ET leakage in ventilated neonates using uncuffed ETs.

Methods: Patient records of 163 neonates ventilated with Babylog 8000 for ≥5h with median (range) gestation age 31.1 (23.3–41.9) weeks and median birth weight 1470g (410–4475g) were evaluated. Ventilator settings, ET leakage, and V_T were recorded every 3h. The lowest, median and highest ET leakage during 24h were noted at the day of first ET leakage (>5%) occurred, at the day on which ET leakage peaked, and at the day of extubation. Results and discussion: An ET leakage >5% was seen in 122 (75%) infants without great clinical relevance. This is because an ET leakage of up to 20% results in volume underestimation of about 10% of target volume. Neonates with ET leakage, compared with those without, had a longer duration of mechanical ventilation (p<0.001), a lower gestational age (p=0.004), a reduced birth weight (p=0.005), and a higher incidence of re-intubation (p=0.003). The greatest ET leakage was seen in infants ventilated with an ET <3mm ID. This means that VLBW infants, in whom V_T is small and adjustment is critical, are at greatest risk for ET leakage. Furthermore, there were no statistically significant correlation was seen between ventilator settings and ET leakage so that previous influencing factors on an airtight placement of the ET may have a higher impact on the ET leakage than the ventilator settings. This study showed that high ET leakages (>40%) occur at times in 42.3% of all infants during the whole duration of mechanical ventilation. The highest ET leakage was commonly seen on the third day of mechanical ventilation and not at the day of extubation. High ET leakages require a suitable ET leakage management, e.g. by change of infant head position, change of ET tube position. If this is not successful and the gas exchange is impaired a re-intubation with a bigger ET tube is indicated. In this study a re-intubation with a bigger ET tube was performed in 27/163 (17%) of all ventilated infants. Conclusion: ET leakage is highly variable and leakage >40% with clinically relevant V_T errors occurred at times in nearly the half of all ventilated neonates. preterm with small-diameter ETs and low birth weight ventilated for long duration were at the highest risk of ET leakage.