Mechanical power in pediatric acute respiratory distress syndrome: a PARDIE study

Abstract

Background: Mechanical power is a composite variable for energy transmitted to the respiratory system over time that may better capture risk for ventilator-induced lung injury than individual ventilator management components. We sought to evaluate if mechanical ventilation management with a high mechanical power is associated with fewer ventilator-free days (VFD) in children with pediatric acute respiratory distress syndrome (PARDS).

Methods: Retrospective analysis of a prospective observational international cohort study.

Results: There were 306 children from 55 pediatric intensive care units included. High mechanical power was associated with younger age, higher oxygenation index, a comorbid condition of bronchopulmonary dysplasia, higher tidal volume, higher delta pressure (peak inspiratory pressure-positive end-expiratory pressure), and higher respiratory rate. Higher mechanical power was associated with fewer 28-day VFD after controlling for confounding variables (per 0.1 J·min^-1·Kg^-1 Subdistribution Hazard Ratio (SHR) 0.93 (0.87, 0.98), p = 0.013). Higher mechanical power was not associated with higher intensive care unit mortality in multivariable analysis in the entire cohort (per 0.1 J·min^-1·Kg^-1 OR 1.12 [0.94, 1.32], p = 0.20). But was associated with higher mortality when excluding children who died due to neurologic reasons (per 0.1 J·min^-1·Kg^-1 OR 1.22 [1.01, 1.46], p = 0.036). In subgroup analyses by age, the association between higher mechanical power and fewer 28-day VFD remained only in children < 2-years-old (per 0.1 J·min^-1·Kg^-1 SHR 0.89 (0.82, 0.96), p = 0.005). Younger children were managed with lower tidal volume, higher delta pressure, higher respiratory rate, lower positive end-expiratory pressure, and higher PCO₂ than older children. No individual ventilator management component mediated the effect of mechanical power on 28-day VFD.

Conclusions: Higher mechanical power is associated with fewer 28-day VFDs in children with PARDS. This association is strongest in children < 2-years-old in whom there are notable differences in mechanical ventilation management. While further validation is needed, these data highlight that ventilator management is associated with outcome in children with PARDS, and there may be subgroups of children with higher potential benefit from strategies to improve lung-protective ventilation.

Take home message: Higher mechanical power is associated with fewer 28-day ventilator-free days in children with pediatric acute respiratory distress syndrome. This association is strongest in children <2-years-old in whom there are notable differences in mechanical ventilation management.

Keywords: Critical care; Mechanical; Pediatrics; Ventilator-induced lung injury; Ventilators.

Fig. 1

Enrollment Flow Chart. Non-conventional ventilation included high frequency oscillatory ventilation and airway pressure release ventilation. Data required to calculate mechanical power included predicted body weight (requires height to calculate) and ventilator management variables

Fig. 2

Adjusted Mean Mortality Proportion by Mechanical Power Deciles (excluding children who died from neurologic injury). Black squares represent mean, and whiskers represent 95% confidence interval. The mean mortality proportion was calculated after multivariable adjustment for the pre-specified pediatric acute respiratory distress syndrome (PARDS) severity of illness score, a comorbidity of bronchopulmonary dysplasia, height, PCO₂, and mode of ventilation. The pre-specified PARDS severity of illness score adjusts for immunocompromised conditions, the 6-h PaO₂/FiO₂ ratio, and the fluid balance, vasopressor-inotrope score, and organ dysfunction on the first day of PARDS