Inspiratory Flow Amplitude in Pediatric Acute Respiratory Distress Syndrome: Outcomes in a Single-Center Cohort, 2023-2024.

OBJECTIVES

To evaluate whether inspiratory flow amplitude is independently associated with time to successful extubation in children with pediatric acute respiratory distress syndrome (PARDS) ventilated within lung-protective targets.

DESIGN

Post hoc analysis of a pulmonary physiologic and clinical dataset collected in 2023-2024.

SETTING

Single tertiary PICU.

PATIENTS: Forty-eight mechanically ventilated children with early PARDS.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN

RESULTS

Standardized measurements of ventilatory parameters and respiratory mechanics collected within 2 hours of intubation during volume-controlled ventilation (VCV) with constant inspiratory flow and neuromuscular blockade. Inspiratory flow amplitude was the ventilator-reported mean inspiratory flow in VCV, a derived, setting-dependent metric. Median (interquartile range [IQR]) age was 11 months (IQR, 3-22 mo), and most patients had mild-to-moderate PARDS of viral etiology. Ventilation was delivered within protective limits for tidal volume, plateau pressure, positive end-expiratory pressure, driving pressure, and inspiratory time. The median inspiratory flow amplitude was 0.9 L/min/kg (IQR, 0.6-1.1 L/min/kg). The primary outcome was time to successful extubation. In multivariable Cox proportional hazards regression adjusted for age, oxygenation index, tidal volume, respiratory rate, and resistive airway pressure (peak inspiratory pressure minus plateau pressure), higher inspiratory flow amplitude was independently associated with a lower hazard of successful extubation over time (hazard ratio, 0.20; 95% CI, 0.06-0.75; p = 0.017). Multicollinearity assessment showed no clinically relevant collinearity among covariates. Sensitivity analyses confirmed the robustness and directional consistency of this association. In complementary linear regression, each 0.1 L/min/kg increase in inspiratory flow amplitude was associated with 3.5 hours (95% CI, 0.7-6.3 hr) of prolonged mechanical ventilation.

CONCLUSIONS

Among children with early PARDS ventilated within lung-protective limits, higher inspiratory flow amplitude was independently associated with delayed extubation. Inspiratory flow amplitude may represent an integrative marker of dynamic ventilatory load not fully captured by conventional static parameters. These findings are observational and hypothesis-generating and support further investigation of inspiratory flow in PARDS.