Tracheal tube airleak in clinical practice and impact on tidal volume measurement in ventilated neonates

Objective: To determine the prevalence, size, and factors affecting tracheal tube (TT) leak in clinical practice and their influence on the displayed tidal volume (V-T) in ventilated newborn infants using uncuffed TTs. Monitoring of V-T 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 Baby-log 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 V-T 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. (Pediatr Crit Care Med 2011; 12:197-202)