The Relevance of Airway Resistance in Children Requiring Mechanical Ventilatory Support.

Objectives: To describe pulmonary resistance in children undergoing invasive mechanical ventilation (MV) for different causes.

Design: A cross-sectional study.

Setting: Two PICUs in the South region of Brazil.

Patients: Children 1 month to 15 years old undergoing MV for more than 24 hours were included. We recorded ventilator variables and measured pulmonary mechanics (inspiratory and expiratory resistance, auto positive end-expiratory pressure [PEEP], and dynamic and static compliance) in the first 48 hours of MV.

Interventions: Measurements of the respiratory mechanics variables during neuromuscular blockade.

Measurements and main results: A total of 113 children were included, 5 months (median [interquartile range (IQR) [2.0-21.5 mo]) old, and median (IQR) weight 6.5 kg (4.5-11.0 kg), with 60% male. Median (IQR) peak inspiratory pressure (PIP) was 30 cm H 2 O (26-35 cm H 2 O), and median (IQR) PEEP was 5 cm H 2 O (5-7 cm H 2 O). The median (IQR) duration of MV was 7 days (5-9 d), and mortality was nine of 113 (8%). The median (IQR) inspiratory and expiratory resistances were 94.0 cm H 2 O/L/s (52.5-155.5 cm H 2 O/L/s) and 117 cm H 2 O/L/s (71-162 cm H 2 O/L/s), with negative association with weight and age (Spearman -0.850). When we assess weight, in smaller children (< 10 kg) had increased pulmonary resistance, with mean values over 100 mH 2 O/L/s, which were higher than larger children ( p < 0.001).

Conclusions: Increased pulmonary resistance is prevalent in the pediatric population undergoing invasive MV. Especially in children less than 1 year old, this variable should be considered when defining a ventilatory strategy.