(666) Utilization of Lung Ultrasound to Assess Inflation in Pediatric ARDS: A Case Series

Introduction: Recently released national guidelines for pediatric acute respiratory distress syndrome (PARDS) specify the need to optimize positive end expiratory pressure (PEEP) to maximize oxygen delivery and prevent ventilator-induced lung injury, but considerable variability exists in how this is accomplished. Lung ultrasound (LUS) is readily available at the bedside and lung aeration scoring with ultrasound has been described in adult patients with ARDS. The use of LUS in PARDS, however, has not been well described, and we sought to investigate whether LUS could be used to identify changes in lung aeration at differing levels of PEEP in PARDS patients to serve as an additional metric in identifying an individual’s optimal PEEP level.

Description: A convenience sample of four pediatric patients with moderate PARDS (OI range 8-12; age range 2-14 years old; 3 with direct lung injury, 1 with indirect lung injury) were enrolled in this study. Each patient had a decremental PEEP titration performed with initial inflation to 14 cm H2O and then serial decreases by 2 cm H2O every 30 minutes down to final inflation of 6 cm H2O. LUS was scored in 12 lung fields with a previously described scoring tool at each PEEP level, with higher scores being associated with better aeration. FiO2 and static compliance were also measured at each PEEP level for comparison at the time of ultrasound. Ultrasound scores were higher at PEEP 14 cm H2O than PEEP 6 cm H2O in all patients. Patients had a median of 3 (range 2-5) lung segments with variability in scores across different levels of PEEP. In general, an increase in lung ultrasound score did not always correlate with an increase in static lung compliance or decreased FiO2 requirement, but in 3/4 patients, a decrease in lung ultrasound score was associated with worsening compliance and increasing FiO2 requirement.

Discussion: Lung ultrasound appeared to be more sensitive to PEEP-related loss of aeration than gain of aeration, likely reflective of ultrasound’s poor ability to visualize overdistention, but high sensitivity for atelectatic changes. This merits further study to see how LUS could be applied to complement commonly employed metrics with a goal of optimizing PEEP in PARDS patients and to potentially improve outcomes.